R E P O R T

Comments on the Draft Ecological Risk Assessment for

General Electric (GE) Housatonic River Site Rest of River

v bull - v V J V

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Prepared by BBL Sciences Inc

Long Beach California

ARCADIS GampM Inc Portland Maine

LWB Environmental Oak Ridge Tennessee

Branton Environmental Consulting Long Beach California

On behalf of General Electric Company

Pittsfield Massachusetts

June 2003 | U)

Table of Contents Section 1 Introduction 1-1

Section 2 General Comments 2-1

21 Underlying Studies and Data Omitted 2-1 22 Exclusion of Lines of Evidence Prior to the Weight-of-Evidence Evaluations 2-1 23 Overemphasis on Hazard Quotients 2-2

231 Interpretation of HQs 2-2 232 Conservatism of HQs 2-3

2321 Exposure assumptions 2-4 2322 Effects metrics 2-4

24 Exclusion of Data Quality from Weight-of-Evidence Evaluations 2-5 25 Discussion of Evidence Regarding Abundant Populations 2-5 26 Extrapolation across Species and Reaches 2-5

261 Risk Comparisons across Species 2-6 262 Extrapolations to Downstream Reaches 2-6

27 Characterization of GEs Position 2-7 28 Non-PCB Constituents 2-7

Section 3 Specific Comments 3-1

31 Benthic Invertebrates 3-1 311 Concentration-Response Analysis to Derive Sediment Toxicity Thresholds 3-1 312 Effects of Grain Size on Study Interpretation 3-1 313 Use of Sediment Quality Values and Toxicity Identification Evaluation in the

Weight-of-Evidence 3-2 314 Need to Acknowledge Additional Uncertainties 3-2 315 Need for Additional Clarification and Information 3-3

32 Amphibians 3-4 321 Lack of Literature Support for a Toxicity Threshold of 1 mgkg tPCBs in Tissue3-4 322 Lack of Support for a Sediment Toxicity Threshold of 1 mgkg Based on Wood

Frog Study 3-5 323 Need to Consider Additional Relevant Endpoints in Wood Frog Study 3-6 324 Evaluation of the Leopard Frog Study 3-7 325 Need to Acknowledge Additional Uncertainties 3-7 326 Need for Additional Information 3-7 327 Extrapolation of Risks Downstream of the PSA 3-8 328 Error in the Text 3-8

33 Fish 3-8 331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds 3-9 332 Derivation of Literature-Based Toxicity Effects Thresholds 3-9

3321 Lack of basis for tPCB threshold of 14 mgkg 3-9 3322 Lack of basis for TCDDTEQ effects threshold of 43 ngkg 3-11 3323 Consideration of the range of reported effects of tPCBs and TEQs on

fish 3-12 333 Evaluation of Phase I and II Fish Toxicity Studies 3-12

3331 Uncertainty in exposure-response relationships in Phase 1 3-12 3332 Selection of data for development of effect levels from Phase II 3-13

334 Need for More Detailed Information in Appendix F 3-13 3341 Documentation of toxicity thresholds derived from Phase II study 3-13

3342 Documentation of literature-based toxicity thresholds 3-14 335 Consideration of Fish Population Field Studies as Lines of Evidence 3-14 336 Uncertainty Analysis 3-14

34 Insectivorous Birds 3-15 35 Piscivorous and Carnivorous Birds 3-15

351 Concerns Applicable to All Three Species 3-15 3511 Effects metrics 3-15 3512 Presentation of HQs as independent lines of evidence 3-16

352 Robins 3-17 353 Ospreys 3-17

3531 Use of osprey as representative species 3-17 3532 Assumptions applied in HQ 3-18

36 Piscivorous Mammals 3-18 361 Use of Site-Specific Mink Toxicological Assays to Derive Effects Metrics 3-18 362 Apparent Inconsistency in Reported Free Metabolic Rate Slope Term 3-19 363 Newest MinkOtter Survey Data 3-19

37 Omnivorous and Carnivorous Mammals 3-19 371 Calculated Food Ingestion Rates 3-19 372 Effects Metrics 3-19

38 Threatened and Endangered Species 3-19 381 Concerns Applicable to All Receptors Evaluated 3-20 382 Bald Eagles 3-20

3821 Foraging time 3-20 3822 Effects metrics 3-20 3823 Extrapolation of risks downstream of the PSA 3-21

383 American Bitterns 3-22 384 Small-footed Myotis 3-22

Section 4 References 4-1

1 Introduction The General Electric Company (GE) submits these comments to the US Environmental Protection Agency (EPA) on EPAs April 2003 draft of its Ecological Risk Assessment for General Electric (GE)Housatonic River Site Rest of River (hereinafter ERA) These comments were prepared on GEs behalf by BBL Sciences Inc ARCADIS GampM Inc LWB Environmental and Branton Environmental Consulting

GE has many concerns and disagreements with the approaches and inputs used the evaluations provided and the conclusions reached in the ERA However in light of discussions with EPA these comments do not discuss all of GEs concerns and disagreements with the ERA In several prior submissions to EPA GE andor its consultants have presented both general and specific comments on EPAs ERA work plans and on the plans and reports on many of the underlying studies that were performed by EPA contractors and included in the ERA The present comments do not repeat all of those points again Rather the focus of these comments is to provide input to EPA that will improve the ERA prior to the next draft In particular GE has attempted to focus these comments on major issues involving errors or internal inconsistencies in the ERA evaluations or conclusions that we believe are not supported by the evidence and uncertainties that we believe should be more explicitly recognized in the ERA However GE preserves its positions on all issues and points on which it has previously submitted comments to EPA and reserves the right to raise these or any other issues or points in its comments on the ERA during the public comment period andor in its presentations to the Peer Review Panel for the ERA The fact that GE has not raised a particular issue in these comments should not be regarded as agreement to the way in which the ERA has addressed that issue

In addition GE has provided EPA with reports on a number of ecological studies conducted by GE contractors over the past few years which we believe are directly relevant to the ERA Although the current draft ERA mentions these studies it does not discuss them or include them in any of the evaluations or weight-of-evidence analyses in the ERA The current draft notes that these GE studies will be discussed and evaluated in the next draft of the ERA However given the absence of such a discussion or evaluation in the current draft GE is unable to offer comments on EPAs assessment of these studies or how EPAs consideration of them may or should change EPAs overall evaluation or conclusions regarding the receptors involved in these studies In its comments during the public comment period andor in its presentations to the Peer Review Panel GE will provide comments on EPAs discussion evaluation and weighting of these studies in the next draft of the ERA as well as on the implications of these studies for the assessment of potential impacts to local populations and communities of these receptors

These comments are organized as follows Section 2 provides a number of general comments that apply to multiple assessment endpoints or the overall approach used to evaluate risk in this ERA including its overall approach to evaluating the available lines of evidence and implementing the weight-of-evidence analyses and its procedures for extrapolating risks to species and areas that were not studied Section 3 then provides more specific comments on each of the receptor groups considered in the ERA as well as examples of some of the issues raised in Section 2

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2 General Comments A number of general issues apply to multiple assessment endpoints or the overall approach used to evaluate risk in this ERA The general issues discussed below include (a) omission of underlying studies and data (b) exclusion of lines of evidence prior to the weight-of-evidence evaluations (c) overemphasis on hazard quotients (HQs) based on modeled exposures and effects (d) exclusion of data quality from the weight-of-evidence evaluations (e) discussion of evidence regarding abundant populations (f) extrapolations across species and reaches (g) characterization of GEs position and (h) treatment of constituents other than polychlorinated biphenyls (PCBs)

21 Underlying Studies and Data Omitted Neither the reports on the studies that form the basis for many of the measurement endpoints nor the underlying database are provided within or in attachments to the ERA In the absence of the underlying studies and data it is not possible to independently validate calculations statistics or interpretation of those studies EPAs (2002b) Guidelines for Ensuring the Quality Objectivity Utility and Integrity of Information Disseminated by the Environmental Protection Agency emphasize the importance of the reproducibility of such information by qualified third parties (EPA 2002b pp 20-21) GE believes that to ensure the transparency of the ERA the underlying study reports and database should be included as appendices to the ERA (in either paper or electronic form) Through that approach if a commenter or member of the Peer Review Panel wishes to evaluate the underlying basis for a statement or conclusion in the ERA the information necessary to do so will be available

22 Exclusion of Lines of Evidence Prior to the Weight-of-Evidence Evaluations The ERA screens out select lines of evidence (mainly some field studies conducted by EPA contractors) prior to the weight-of-evidence evaluations instead of including all available lines of evidence in the weight-of-evidence evaluations In GEs view this practice is not consistent with the purposes of performing a weight-of-evidence evaluation mdash ie to consider the scientific defensibility of all available lines of evidence to reconcile those lines of evidence and to conclude whether significant risk of harm is posed to the environment (Menzie et al 1996) Moreover this approach does not appear to be systematically applied across receptors For example EPAs fish biomass study is excluded from the weight-of-evidence evaluation on the ground that meaningful statistical assessment of PCS or TEQ relationship to fish community parameters was not feasible (p 5-43) However the qualitative observations of amphibian community structure and the minkotter surveys are (appropriately) included in the weight-of-evidence evaluation despite the fact that like the biomass study statistical evaluations of exposure-response are not possible Additionally the avian surveys are not included in the weight-of-evidence evaluations even though they are initially listed as measurement endpoints for evaluating threatened and endangered species (p 11-6)

GE urges EPA to include all available lines of evidence in the weight-of-evidence evaluations These would include all field-based studies that EPA conducted as well as all studies conducted by GE contractors

In addition for some studies (eg EPAs wood frog study and its Phase II fish toxicity study) the draft ERA includes only a subset of the available endpoints in the weight-of-evidence evaluations as

discussed further in Section 3 In such cases GE urges EPA to evaluate all available and relevant individual lines of evidence from these particular studies

23 Overemphasis on Hazard Quotients The ERA derives Hazard Quotients (HQs) from modeled exposure and effects for the majority of receptors and assesses them as lines of evidence typically according them moderatehigh or high weight In addition the Risk Summary (Section 12) presents the Monte Carlo-based HQs for all receptors to facilitate comparison of risks among aquatic life and wildlife receptors and to give a broad overview of the findings of the risk assessment (p 12-3) Indeed in that section the consideration of other lines of evidence is restricted to a very brief risk characterization that acknowledges that some of the receptors were evaluated based on multiple lines of evidence but does not put the HQs which represent only one of these lines of evidence into this context (pp 12-54 through 12-55) As a result the HQs dominate the presentation of risk in that section

These practices place too much weight and emphasis on the HQs relative to other lines of evidence and tends to obscure the high degree of conservatism and uncertainty associated with the HQs GEs concerns regarding the ERAs interpretation of the HQs and the conservatism and uncertainties present in them are discussed below

231 Interpretation of HQs GE has several concerns with the ERAs interpretation of HQs First in applying the weight-ofshyevidence approach to the HQs the ERA generally does not consider all aspects of the degree of association attribute as defined by Menzie et al (1996) and does not adequately account for limitations in the species-specificity of key input variables Second the HQs are presented in a manner that erroneously suggests that they reflect a full range of individual exposures within the local population Finally the presentation of HQs is confusing in some respects These concerns are further detailed in this section

In applying the weight-of-evidence approach to the HQs the ERA generally assigns moderatehigh or high weight to the great majority of attributes GE believes that a correct application of the Menzie et al (1996) method would yield lower weights for certain of these attributes For example as discussed below the ERA generally scores the HQs moderatehigh or high for the degree of association between the measurement endpoint and the assessment endpoint based primarily on species-specificity whereas GE believes that the HQs should receive low to moderate scores for these attributes

For most of the HQs the rationale provided in the ERA for assignment of a weight related to degree of association refers only to the species-specificity of the study (pp F-52 G-51 H-501-66 J-51 K-68 shyK-69 Tables F4-7 G4-3 H4-314-4 J4-4 K4-3) Based on the Menzie et al (1996) definition as recognized in the ERA (p 2-68) degree of association refers to the extent to which the measurement endpoint is representative of correlated with or applicable to the assessment endpoint in particular with respect to similarity of effect target organ mechanism of action and level of ecological organization (Menzie et al 1996) Hence while species-specificity is part of the definition of degree of association it is not the sole characteristic of that attribute Other aspects of the biological linkage such as the level of ecological organization should also be considered For example EPA guidance states that the assessment endpoints in Superfund ecological risk assessments should address potential

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adverse effects to local populations and communities of biota (EPA 1999 p 5) While that guidance also notes as the ERA states (p 12-47) that impacts on local populations and communities can be estimated by extrapolating from effects on individuals and groups of individuals using a lines-ofshyevidence approach (EPA 1999 p 3) it should be recognized that lines of evidence such as HQ models which do not address population-level effects should receive lower weight in estimating the degree of association with the population-level assessment endpoints Thus GE recommends that the degree of association of each measurement endpoint be evaluated in accordance with the full definition provided by Menzie et al (1996) including consideration of the level of ecological organization

Moreover in evaluating the species-sensitivity aspect of this attribute the ERA does not adequately account for limited species-specificity in the modeled food intake rates fractions of diets derived from the site or effects metrics The food intake rates are calculated using generic allometric equations and input variables that in some cases are not specific to either the preferred prey of the receptor of interest or the receptor itself The assumption that all receptors (except mink) derive 100 of their food from the Primary Study Area (PSA) also does not account for species-specific foraging ranges Although the use of effects metrics based on species in different taxonomic orders from the receptors of interest is recognized in the weight-of-evidence evaluations it only results in scores being reduced from high to moderatehigh A greater decrease in the score is warranted given the significant uncertainties in interspecies extrapolations Hence the most important variables used in the derivation of HQs generally are not species-specific and the weight-of-evidence scores should be lowered on that basis This problem could be ameliorated for some receptors by basing the HQs where possible on site-specific exposure and effects data for the species in question

Further the ERAs presentation of HQ ranges based on distributions of doses (ie lower bound Monte Carlo and upper bound) suggests that the HQs simulate a full range of exposures to individuals within the local population In actuality the upper bound and Monte Carlo HQs presented in the ERA are based on exposures that represent at most a small number of individuals - namely those that derive 100 of their prey from the PSA (except in the case of mink) and only consume prey that contain the highest concentrations of chemicals of potential concern (COPCs) The ERAs use of point estimates for the parameters of proportion of prey derived from the PSA and concentration of COPCs in prey restricts the applicability of the output of the analyses to a very small number of individuals if any to which these exposure parameters might apply As discussed further in Section 2321 below GE recommends use of distributions for these two parameters so that the output of the HQs might be applicable to a broader range of individuals inhabiting the PSA

Finally Figures 122-1 through 122-4 (pp 12-612-912-1112-12) are confusing in that they suggest that absolute values of HQs are comparable across species and across media of interest (eg sediment soil prey) In order to improve the transparency of the risk characterization GE recommends replacing Figures 122-1 through 122-4 with summary tables of the weight-of-evidence evaluations for all assessment endpoints in order to offer a more balanced approach to comparison of risks

232 Conservatism of HQs The ERA states that HQs are not conservative because no safety factors were used to estimate the effects metrics (except in the case of the bald eagle) and uncertainties regarding the exposure model inputs were explicitly propagated through the probability bounds of the exposure model (p 12-10) While GE recognizes that such safety factors are generally not included in the HQ analyses

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considerable conservatism is contributed to the HQs by both the exposure assumptions and the effects metrics If these sources of conservatism are not corrected through alternate assumptions then the conservatism that they contribute should be explicitly acknowledged in the ERA Some of the general sources of conservatism are discussed below while specific comments on the individual receptors are provided in Section 3

2321 Exposure assumptions For all receptors the ERA states that because food intake rates are poorly characterized in the literature it is necessary to model food intake rates based on allometric equations provided in the Wildlife Exposure Factors Handbook (EPA 1993) (eg pp 7-16 8-17 9-13 10-13 11-13) In fact however the EPA (1993) handbook provides measured species-specific food intake rates for all receptor species evaluated in the ERA except tree swallows river otters American bitterns and small-footed myotis According to EPA (1993) measured species-specific values are preferred over modeling intake rates based on allometric equations (p 3-1) GE recommends the use of the species-specific food intake rates reported in the Wildlife Exposure Factors Handbook (EPA 1993) Where that is not or cannot be done the uncertainty associated with using generic allometric equations and input variables that are not species-specific should be discussed and accounted for in the weight-ofshyevidence evaluations

In addition the use of point estimates to characterize the concentrations of COPCs in food and proportion of food derived from the site appears to be inconsistent with the ERAs own criteria for the use of distributions and point estimates The ERA states that point estimates [are used] for minor variables or variables with low coefficients of variation (p 6-17 H-7) Although coefficients of variation are not presented in the ERA and the sensitivity analyses exclude variables characterized with point estimates concentrations of COPCs in food and proportion of diet derived from the site cannot be described as minor because they directly control the magnitude of estimated dose Use of point estimates for these variables prevents uncertainty from being propagated through the probability bounds of the exposure model (p 12-10) and restricts the applicability of the results to those individuals (if any) that only derive their food from the PSA and that always consume food containing the highest concentrations of COPCs In order to align practices applied in the ERA with the stated methodologies GE recommends representation of these variables with appropriate statistical distributions

2322 Effects metrics Many aspects of the effects metrics also contribute to conservatism and uncertainty in the HQs As described in Section 3 these limitations include (for various receptors) the absence of clear documentation of the practices employed in development of the effects metrics lack of support by the underlying studies or failure to reflect the full body of toxicological literature andor lack of acknowledgment of important sources of uncertainty GE recommends revision of the effects metrics in the ERA as discussed in Section 3

The ERA (eg p 6-20) also states that in all cases effects metrics were consistent with the metrics used in the exposure analysis However the ways in which they are consistent are not defined While the effects metrics and exposure analyses are consistent with respect to units (eg mgkg-day) in many cases they are inconsistent with respect to species exposure duration and dosing regime For example an effect metric based on a domesticated species (ie white leghorn chickens) cannot be

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considered consistent with exposure metrics for wild avian receptors GE recommends revising the above statement so that it specifies the ways in which effects metrics are consistent with exposure metrics GE also recommends that the weight-of-evidence evaluations be modified to account for inconsistencies with respect to species exposure duration and dosing regime

24 Exclusion of Data Quality from Weight-of-Evidence Evaluations Based on Menzie et als (1996) quantitative weight-of-evidence approach data quality is one of the most important attributes in determining the scientific defensibility of a measurement endpoint Nonetheless the ERA does not include data quality as an attribute in the weight-of-evidence evaluations Instead the ERA asserts that all studies used in the ERA (except those conducted by GE contractors) have adequate data quality (p 2-70) However the criteria for determining the adequacy of data quality are not defined the process and outcome of a data quality evaluation are not provided and the underlying studies and data are not provided Consequently it is not possible to verify the validity of the assumption that all data have adequate quality In addition this approach implies that data quality for all measurement endpoints based on EPAs studies are equal In fact data quality varies considerably among the underlying studies For example errors and inconsistencies in the databases and analyses presented in underlying studies were identified in comments that GE has previously submitted to EPA The exclusion of data quality from the weight-of-evidence evaluation prevents EPA from accounting for those differences hi data quality

For these reasons GE urges EPA to modify the ERA so that it (a) specifies all necessary information to allow an independent evaluation of data quality for each measurement endpoint (b) includes the attribute of data quality in the weight-of-evidence evaluations and (c) acknowledges any data quality limitations

25 Discussion of Evidence Regarding Abundant Populations Section 12322 of the ERA lists a number of factors that it asserts indicate that studies showing an abundant population of a given receptor at the site do not demonstrate a lack of adverse effects on that population (pp 12-48 through 12-50) The ERA claims that (a) removal of predators compensates for direct effects of contaminants (b) immigration compensates for direct effects of contaminants (c) populations exposed to COPCs may be more vulnerable to other stressors in the future due to chemical adaptation andor immune system effects The application of these theories to a specific site such as the PSA is speculative and unsupported by the underlying studies None of the studies discussed in the ERA was designed to evaluate these types of effects GE believes that this entire discussion should be deleted from the ERA as speculative and unsupported by the data

26 Extrapolation across Species and Reaches The ERA extrapolates findings for risks posed to individual receptors within the PSA to other species and to areas outside the PSA There are several limitations associated with these practices as discussed below

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261 Risk Comparisons across Species The ERA qualitatively extrapolates predicted risks for each receptor to other species within the same feeding guild based on factors that influence exposure to COPCs (eg diet foraging range body weight) There are a number of problems with this approach First in the absence of data on the other species these extrapolations are not supported by any actual evidence Second these extrapolations of risk do not recognize that risk is a function not only of exposure but also of toxicological sensitivity By making the extrapolations based on factors that relate solely to exposure the ERA implies that all species within a feeding guild are equally sensitive to the toxicological effects of the COPCs However as demonstrated by Brunstrom and Lund (1988) toxicological sensitivity can vary by orders of magnitude across species even for species in the same feeding guild and taxonomic order (eg chickens and turkeys) Hence these analyses should not be referred to as comparisons of risk

The interspecies extrapolations also do not account for field data that either support or refute qualitative conclusions regarding relative risks For example data collected by the Massachusetts Division of Fisheries and Wildlife since 1980 on the productivity of great blue herons throughout Massachusetts show no differences in the numbers of young per nest for herons breeding within or beyond foraging distance of the PSA (MDFW 1979 1980 1981 1982 1983 1984 1985 1986ab 1987 1989 1991 1996) This finding does not support the ERAs qualitative finding that great blue herons face similar to higher risks than American bitterns which are predicted to have high risks (p 12-36)

GE recommends that extrapolations of risk estimates from receptors of interest to other species be omitted from the ERA because they are too uncertain to provide useful information If they are retained GE recommends that the comparisons be accurately characterized as comparisons of potential exposure rather than as comparisons of risk Regardless of how the extrapolations are presented however uncertainties should be explicitly reported including both the inability of the analysis to account for interspecies differences in toxicological sensitivity and cases where available field data contradict the extrapolated findings

262 Extrapolations to Downstream Reaches The field studies surveys and sampling program conducted for the ERA primarily focus on the PSA In an effort to apply the analyses across the entire study area the ERA extrapolates risks downstream of the PSA for seven receptors (benthic invertebrates amphibians warm water fish trout mink otter and bald eagles) For each of these groups the ERA identifies a maximum acceptable threshold concentration (MATC) for total PCBs (tPCBs) Each MATC is then compared to exposure concentrations for individual river and floodplain reaches downstream of Woods Pond to Long Island Sound Areas where exposure concentrations exceed the MATCs are interpreted as indicating potential risks

GE recommends several improvements in this approach (a) revision of the MATCs (b) improved spatial resolution of the overlap between predictions of risk to each receptor and the availability of suitable habitat for those receptors and (c) an explicit discussion of the uncertainties associated with these extrapolations In addition more complete documentation of the methodologies and assumptions employed would enhance the transparency of the analysis

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First several of the MATCs (eg for benthic invertebrates amphibians fish and bald eagles) are not supported by the site-specific studies or the scientific literature Specific concerns related to the basis for these MATCs are discussed below in Sections 311 (benthic invertebrates) 321 amp 322 (amphibians) 332 amp 333 (fish) and 3822 (bald eagles) GE recommends that these MATCs be revised

Second the applicability of the benchmark comparisons for each of the seven receptors should also be considered relative to the available habitat for such receptors in the downstream reaches For example although the MATC for amphibians was developed based on sediment tPCB concentrations in breeding ponds it was applied downstream of Woods Pond to soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data in the downstream reaches (p 12-15) Although such data may be lacking the ERA should make clear that the extrapolation applies only to sediment in potential floodplain ponds downstream of Woods Pond In addition risks to mink otters and bald eagles are evaluated for all reaches of the river with adequate data on exposure concentrations regardless of habitat Restricting the assessment of risks for these receptors to those reaches with suitable habitat would further improve the accuracy of these extrapolations

Third uncertainties in the extrapolations should be discussed and the results should be subjected to a separate weight-of-evidence evaluation

Finally the ERA does not provide enough information regarding the actual methodologies and assumptions used in the analysis of risks downstream of Woods Pond Transparency in this analysis is of paramount importance given the potential influence and use of these extrapolated risk results In particular the ERA should report the actual exposure concentrations used and whether they are spatially weighted averages arithmetic averages 95 upper confidence limits (UCLs) maxima etc In addition EPA should provide at least general information regarding the suitability of the downstream habitat for these receptors or where such information does not exist acknowledge that habitat has not been evaluated and could have a significant effect on any risks downstream of Woods Pond

27 Characterization of GEs Position In several places (pp 2-60 2-61) the ERA characterizes GEs position GE requests that such descriptions of GEs position be removed from the ERA GE will present its position in its comments during the public comment period andor to the Peer Review Panel

28 Non-PCB Constituents The ERA covers the Rest of River which is defined in the Consent Decree (Paragraph 6) as the Housatonic River and its sediments and floodplain areas downstream of the Confluence of the East and West Branches of the Housatonic River including backwaters except for ActualPotential Lawns to the extent that such areas are areas to which Waste Materials that originated at the GE Plant Area have migrated and which are being investigated or remediated pursuant to this Consent Decree (emphasis added) The Revised RCRA Permit contains a similar definition (Definition 19) limiting the Rest of River areas to areas to which releases of hazardous wastes andor hazardous constituents are migrating or have migrated from the GE Facility

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The ERA recognizes that the Rest of River includes areas of the Housatonic River and its sediments and floodplain (except ActualPotential Lawns) in which contaminants migrating from the GE facility are located (p 1-2) However it includes as COPCs a number of non-PCB constituents that are or may not be related to releases from the GE facility These include for various media numerous polycyclic aromatic hydrocarbons (PAHs) and other semi-volatile organic compounds (SVOCs) dioxins and furans several metals and (for fish) certain pesticides (Tables 24-2 through 24-5) There are multiple potential sources of these constituents in the Rest of River area not just releases from the GE facility

To avoid any confusion the ERA should make clear in its discussions of the COPCs (Sections 231 and 243) that while several COPCs other than PCBs have been selected for the ERA there are multiple potential sources of these constituents and hence there is no evidence demonstrating that the occurrence of these COPCs in the Rest of River area is necessarily derived from releases attributable to GE

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3 Specific Comments

31 Benthic Invertebrates In its assessment of benthic invertebrates the ERA derives toxicity thresholds (MATCs) of 3 mgkg tPCB in both tissue (based on the literature) and sediments (based on the results of toxicity and benthic community studies) GE believes that these thresholds should be reevaluated As discussed in this section GE urges EPA to make the following changes to the ERAs assessment of benthic invertebrates (a) use a different data set to calculate sediment-based toxicity thresholds (b) take adequate account of sediment grain size in interpreting the benthic community and toxicity test results (c) reduce the emphasis on Sediment Quality Values and the Toxicity Identification Evaluation (TIE) results (d) recognize a number of additional specified uncertainties and (e) clarify or provide additional information on certain issues

311 Concentration-Response Analysis to Derive Sediment Toxicity Thresholds The ERA concludes that the toxicity studies showed ecologically significant effects at sediment tPCB concentrations of 3 mgkg or higher (pp 3-71 D-98) the proposed MATC for sediment This proposed toxicity threshold is apparently based on LCso and ICso values from laboratory studies that were calculated based on the median values of multiple grab samples (p D-10) (some of which were collected independently of the laboratory bioassays) rather than based on measured concentrations of PCBs in sediments actually used in these bioassays The use of these unrelated data as a basis for establishing exposure levels in laboratory bioassays is of concern given that PCB concentrations in sediments of the Housatonic River can vary by orders of magnitude over very small spatial and temporal scales (pp D-26 to D-28) The rationale given for this method is that combining data from sampling events that are approximately (but not exactly) synoptic with the effects data more accurately portrays the COC concentrations at each station (p D-27) This approach may provide an indication of PCB concentrations in the vicinity of a station over time but it does not provide a better measure of PCB concentrations in the specific composites used in the bioassays than would a direct measure of PCBs in the sediments used in the bioassays For some stations concentrations measured directly from the composites are in fact substantially different than those derived from other collection efforts (Figures D3-1 through D3-5 Stations 7 and 8A) resulting in variability which likely substantially affects the exposure-response analyses and resulting LCsos and ICsoS Because of this variability it is important that effects levels for bioassay tests be calculated from the data that represent the concentrations to which these organisms were actually exposed

GE recommends that the ERA be revised to calculate the No Observed Adverse Effect Levels (NOAELs) Lowest Observed Adverse Effect Levels (LOAELs) and LCsoICso values for the laboratory bioassays (Tables D4-2 and D4-3) based on the synoptic values derived directly from the composite samples for the laboratory bioassays because these values best represent the exposures to the test organisms The LCao and IC20 values should also be revised in a similar manner as should the linear regression models (Table D4-4 Figure D4-5)

312 Effects of Grain Size on Study Interpretation Grain size is a significant variable that can impact both benthic community structure and the endpoints evaluated in the laboratory toxicity studies However in several instances the ERA does not adequately consider the effects of grain size in interpreting the study results

The ERA states that the benthic community data indicated that five of the six stations with median tPCB concentrations above 5 mgkg had significant benthic community alteration (p D-98) Those same five stations had coarse-grained sediments (see Figures D4-6 and D4-7) The one fine-grained station with median tPCB concentrations greater than 5 mgkg (Station 8) had higher species richness and abundance than the coarse-grained stations and was not significantly different from the reference stations (see Figures D4-6 D4-7 and D4-15) Benthic invertebrates tend to be the least diverse and the least abundant in sand likely due to its instability (Ward 1992 Minshall 1984 Allan 1995) Thus even in the absence of PCBs the diversity and abundance of invertebrates would be expected to be lower at the coarse-grained stations In these circumstances it is at least equally likely that grain size rather than PCB concentration explains the spatial variations in benthic community structure As a result the statements throughout the ERA regarding the high level of confidence in the conclusion that benthic invertebrates in the Housatonic River experience unacceptable risks due to tPCBs (eg p 12-55) are not be supported Those statements should be revised to recognize the confounding impacts and uncertainty associated with grain size effects and to note that as a result the benthic community data do not provide conclusive evidence of tPCB effects on changes in community structure

Similar concerns apply to the bioassay test The reference stations used in the bioassay test (Al and A3) are coarse-grained (Figure D2-2) whereas the treatment stations showing the highest levels of response (Stations 7 8 and 8A) are fine-grained Statistical analyses and the weight of evidence evaluation are based on comparisons made between Housatonic River sediment stations and references regardless of grain size (Table D3-4 and Figure D4-15) The uncertainty associated with comparing the toxicity of fine-grained stations to coarse-grained reference treatments should be acknowledged

313 Use of Sediment Quality Values and Toxicity Identification Evaluation in the Weight-of-Evidence

The ERA also relies on published Sediment Quality Values (SQVs) to support a sediment toxicity threshold value of 3 to 5 mgkg (pp 3-71 D-98) SQVs are generic in nature and therefore are primarily appropriate in screening-level ERAs when no site-specific data are available (see eg Long et al 1995) Given the availability of substantial site-specific data the generic SQVs should not be used at all or at a minimum given very low weight and the references to them should be removed from the conclusions

The ERA also gives moderate weight to the results of the Toxicity Identification Evaluation (TIE) (Table D4-5) The ERA concludes from this Phase I TIE that PCBs may be the main causal agent in the toxicity studies (p D-78) However the TIE was not a definitive study and was not designed to provide an independent evaluation of effects and the results of the TIE are inconclusive showing only that non-polar organic chemicals were likely responsible for the observed toxicity As a result while the results of the TIE provide some evidence as to the degree to which observed effects can be linked to PCBs rather than other COPCs the TIE study should be removed as a separate line of evidence

314 Need to Acknowledge Additional Uncertainties There are a number of uncertainties associated with the benthic invertebrate studies Some of these are acknowledged in the text (pp D-95 through D-98) but other critical uncertainties are not The text should be revised to acknowledge the following uncertainties

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Lack of concordance between benthic community and sediment toxicity study results At the four stations for which there are both sediment toxicity test data and benthic community data those results are contradictory The sediment toxicity tests show a toxic response for most endpoints (especially at Stations 7 and 8) whereas the benthic community analyses do not (see Figure D4-15) GE recommends that the ERA be revised to discuss this point in the uncertainty section and also to carry this through to the conclusions in terms of the ability to extrapolate the potential for adverse effects to downstream locations

Inconsistent patterns oftPCB concentrations in sediment and tissues The ERA likewise does not discuss the fact that the median tPCB concentrations in sediments and those in tissue are not consistent (eg elevated tPCB concentrations in sediments were not co-located with those in tissue) (compare Figure 33-3 on p 3-18 with Figure 33-6 on p 3-22) These inconsistencies raise questions regarding the reliability of using median sediment concentrations as a measure of exposure for benthic invertebrates They also limit the usefulness of the biota sediment accumulation factors (BSAFs) which range from 08 to 61 (p D-32) in predicting tissue levels from sediment concentrations These inconsistencies should be acknowledged in the discussion of tissue chemistry (Section 335 pp 3-21 and 3-23) and the implications relative to estimating exposure should be addressed in the uncertainty section

Calculation of LC$o and ICso values The toxicity test endpoints presented in Tables D4-1 through D4-3 based on statistical analyses have a number of significant uncertainties Specifically uncertainties are associated with the results in which (a) the chi-square value exceeds the critical value in the derivation of LCjos and LC2os (20 out of 54 endpoints) (b) visual observations rather than the probit analyses were used because the model did not converge (2 out of 54 endpoints) and (c) there was an interrupted dose-response (9 of 54 endpoints) These difficulties with the statistical analyses are indicative of inconsistencies in the dose-response relationships that result in uncertainty surrounding the threshold values These uncertainties should be addressed (Tables D4-1 - D4-3) In addition no explanation is provided for why the highest dose (772 mgkg) for H azteca 48-h survival is excluded from the effects threshold analysis (Table D4-1) Additional information should be included regarding its exclusion or the analyses should be redone using the results of this treatment

Use of single samples to characterize sediment in used in bioassays A discussion of the uncertainty associated with determining exposure values of sediment composites used in toxicity testing based on a single chemistry sample should be provided (p D-17) Alternatively if multiple samples were used to evaluate potential heterogeneity in these composites to confirm that sediment was completely mixed then those data should be provided

315 Need for Additional Clarification and Information This section describes a number of issues for which the next draft of the ERA should provide clarification or additional data or analyses

Tissue effects thresholds from the literature The ERA states that the literature review was focused on Aroclor 1260 and 1254 (p 3-14) It should be revised to state that no effects thresholds were found based on studies with Aroclor 1260 and that only studies of tPCBs Aroclor 1254 and Clophen A50 were used to derive these thresholds The figures summarizing the literature effects thresholds should also be revised to indicate which study is associated with the effects reported (eg in Figure 44-13)

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and to indicate that studies with Clophen A50 are included in the summary In addition congenershyspecific studies should be removed from the literature review (Table D3-5 and Attachment DI) as they are not appropriate surrogates for tPCB toxicity

Multi-dimensional scaling analysis The results of the multi-dimensional scaling (MDS) statistical analyses used to develop Figures D3-15 through D3-17 should be presented This will provide important information regarding the relative contribution of different factors in this multivariate analysis

Derivation of MATCs The ERA does not explain explicitly how the sediment MATC of 3 mgkg tPCB (p 3-72) used to assess the extent of risks downstream from the PSA was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should specifically document the derivation of the MATC value used

32 Amphibians In the assessment of amphibians the ERA derives toxicity thresholds (MATCs) of 1 mgkg in both tissue (based on the literature) and sediments (based on the results of EPAs wood frog study) As discussed below GE believes that neither of these thresholds is supported by the underlying studies and that they should be higher Moreover in evaluating the results of the wood frog study the ERA does not consider certain endpoints (metamorphosis and mortality) that have clear ecological relevance these endpoints should be included in the evaluation In addition as further discussed in these comments we urge EPA to (a) give lower weight to the results of the leopard frog study and explicitly recognize its use of external reference frogs (b) recognize additional specified uncertainties in the amphibian assessment (c) clarify or present additional data or analyses on certain issues (d) modify the extrapolation to reaches downstream of Woods Pond and (e) correct an error in the text1

321 Lack of Literature Support for a Toxicity Threshold of 1 mgkg tPCBs in Tissue The ERA specifies a toxicity threshold of 1 mgkg in tissue based on a review of the literature (pp 4shy75 E-96) The studies and results used in this review are summarized in Figures 44-13 and E3-37 However the two tPCB LOAELs (called LOELs in these figures) below 1 mgkg shown in these figures are not supported by the underlying study (Gutleb et al 2000) One of these effects levels for time to metamorphosis for the African clawed frog is based on exposure to PCB 126 although tissue chemistry was analyzed as tPCBs Comparing tPCB concentrations to effects levels from a study in which larvae were exposed to PCB 126 would substantially overstate tPCB toxicity and hence this effect level should not be used to evaluate potential tPCB effects The second LOAEL for the European common frog is 024 mgkg tPCBs (wet weight2) in tissue (based on exposure to Clophen A50) However at that concentration there was no adverse effect body weight in the exposed frogs was higher not lower than in the control frogs In fact there was no significant effect on body weight at the highest tissue concentration used in this study (112 mgkg tPCBs wet weight) Hence the latter

1 As noted in Section 1 EPA has also agreed to include the frog study sponsored by GE (Resetarits 2002) in the next draft of the ERA In addition GE has recently completed a study of leopard frog egg masses in the PSA and is providing a report on that study to EPA (ARCADIS 2003) That study should likewise be included in the next draft of the ERA

2 As converted from lipid weight in Attachment E2

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value should be reported as an unbounded NOAEL for that endpoint and the value reported as a LOAEL (024 mgkg) should be removed from these figures

Additional concerns associated with the summary of the literature effects are related to the interpretation of the frequency of occurrence of adverse effects (p 4-56 and E-81) First three LOAELs are cited for mortality based on a single experiment (Savage et al 2002) (Figure 4431 p 4shy57 and E3-37 p 60) By definition a LOAEL is the lowest concentration in an experiment for which there is a statistically significant difference relative to the control therefore only the LOAEL at approximately 6 mgkg from this study should be included in this figure When the erroneous LOAEL (Gutleb et al 2000) and the redundant LOAELs (Savage et al 2002) are removed the frequency of adverse effect analysis indicates that 4 out of 12 endpoints (for tPCBs) or 33 demonstrate adverse effects at concentrations greater than 1 mgkg and that in fact no adverse effects are observed below 6 mgkg

In addition the meaning of this frequency of adverse effects is not clear because there are substantive differences between the nature of effects observed For example the endpoints of reduced activity or swimming speed may or may not have the same severity of impact to an individual as increased mortality This distinction is lost in a simple evaluation of frequency of effects between different endpoints in various literature studies

Based on the above discussion the statement that [tjhere were six instances of adverse effects occurring between 1 and 10 mgkg (pp 4-56 and E-81) should be revised For tPCBs there are only three LOAELs (ie incidence of adverse effects) between 1 and 10 mgkg and all them are at or above 6 mgkg The text should be revised accordingly If the interpretation of these studies based on the frequency of adverse effects is retained that text should also be revised and uncertainties associated with direct comparisons of the different kinds of effects included in this analysis should be acknowledged

322 Lack of Support for a Sediment Toxicity Threshold of 1 mgkg Based on Wood Frog Study

The sediment toxicity threshold of 1 mgkg is apparently based primarily on an analysis of the results of EPAs wood frog study However the description of the results of that study states that [e]cologically significant adverse effects in late stage juvenile wood frogs occurred in the sediment tPCB concentration range of 10 to 60 mgkg although responses of lesser magnitude yet statistically significant were observed at 5 mgkg tPCB and lower (p 4-60) The latter statement (which may be the basis for the threshold) is apparently derived from the wood frog NOAELs and LOAELs presented in Table E4-2 However there are several problems or inconsistencies in the derivation of site-specific NOAELs and LOAELs presented in Table E4-2

bull In several instances the NOAELs and LOAELs do not coincide with sediment concentrations that are associated with the effects data For example the spatially weighted mean tPCB value of 136 mgkg is presented as either a NOAEL or LOAEL for all four endpoints in Table E4-2 However it appears that this value is associated with a vernal pool (46-VP-4 Table E2-8) that has no effects data associated with it (see Tables E3-5- E3-6 and E 310 - E3-11)

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bull It appears that the reference WML-1 has been excluded from the calculation of NOAELs and LOAELs for Phase III metamorphs because of zero response at this concentration(Table E4-2) This exclusion is not warranted While the text refers to the tissue tPCB concentration for reference location WML-1 in the Phase III of the wood frog study as anomalous (eg p 4-52) no problems with data quality are reported that would indicate that the organism did not in fact have a tissue burden of 44 mgkg tPCBs As a result responses associated with this exposure level should be considered to represent part of the range of effects and all analyses of exposure and effect should include this reference site Statistical comparisons with a zero value are commonly made using a value marginally greater than zero (eg 000001)

bull Concentration-response relationships for each endpoint were evaluated using both (1) the most synoptic chemistry value paired with each toxicity endpoint (also referred to as vernal pool sediment) and (2) a combined data set used to generate a spatially weighted surface average (pp 4shy16 mdash 4-17) Given the variability in sediment concentrations the samples used in the laboratory toxicity study should not be assumed to be equivalent to the surface weighted average The synoptic (ie vernal pool) data reflect the actual tPCB concentrations measured in sediments used in the laboratory exposures and should thus should be used for analyses of the Phase I wood frog study which was conducted in the laboratory The surface weighted averages should be used for the analysis of Phase II and Phase III studies in which larvae and metamorphs were exposed in the field as they encompass the range of concentrations to which the growing larvae and metamorphs might have been exposed to The NOAELs LOAELs and point estimates for effects concentrations (eg LC50 and LC20) (Table E4-2) should be revised accordingly

bull Table E4-2 states that the reference site had no malformed specimens (Phase II metamorphs percent malformed) In fact Table E3-11 indicates that reference site WML-3 had 29 malformations

Moreover the toxicity threshold for wood frogs was derived based only on endpoints that showed effects The ERA states that if no discern[i]ble differences in effect levels across treatments were observed (ie inadequate range in response variable) the effects endpoint was not considered in the detailed statistical evaluation (p E-90) As a result as discussed in the next section the lack of PCB-related effects for key endpoints (ie mortality and metamorphosis) were not considered in the derivation of the effects threshold Consideration of the results for those omitted endpoints shows further that the sediment MATC of 1 mgkg is too low

We also note that although Appendix E presents tissue-based HQs for leopard frogs and wood frogs (pp E-96 - E-98) Section 12 of the ERA presents only sediment-based HQs (Figures 122-1 and p 12shy7) Tissue concentrations provide a more direct measure of exposure than do sediment concentrations and hence the tissue-based rather than sediment-based HQs should be used in Section 12

323 Need to Consider Additional Relevant Endpoints in Wood Frog Study As noted above in evaluating the results of the wood frog study two endpoints with clear ecological relevance ~ metamorphosis and mortality -- were screened out of the formal concentration-response modeling due to a lack of discern[i]ble differences in effect levels across treatments (p E-90) However these two endpoints integrate other effects (ie the most serious effect of malformations would be reduced metamorphosis and increased mortality) and should be carried through the

concentration-response evaluation If no concentration-response curve can be derived because there were no effects then the highest dose should be treated as a NOAEL for these endpoints the LC50

should be expressed as gt highest dose and both mortality and metamorphosis should be considered subsequently as part of the lines-of-evidence evaluation

324 Evaluation of the Leopard Frog Study EPAs leopard frog study receives the same overall weight (moderatehigh) as its wood frog study in the weight-of evidence-evaluation (Table 45-4 p 4-69) Considering the significant problems with the leopard frog study as detailed in GEs comments on this study (BBL Sciences et al 2003a) it should be accorded a low weight

Moreover the text does not consistently acknowledge that reference frogs for the leopard frog study were obtained from a biological supply company For readers unfamiliar with the underlying study this could lead to misinterpretations of the results presented The text should be modified to clearly represent this aspect of the leopard frog study as well as additional qualifications as follows

bull The first time the study design of the leopard frog study is presented it should be clearly stated that no frogs or eggslarvae were found in the reference areas (p 4-13)

bull The text that describes comparisons between both the toxicity studies and the community evaluations and appropriately matched field references (p 4-27) should be revised to indicate that for the leopard frog study the field reference was limited to sediment not frogs collected from a reference pond

bull Although the text states that reference ponds were surveyed for eggs and larvae it does not indicate that in addition to no eggs or larvae being found at four of nine contaminated sites none were found at the reference sites (p 4-35)

bull Similarly the summary of female leopard frog reproductive fitness identifies all of the Housatonic River sites that were not gravid (did not have eggs mature enough for successful fertilization) (p 4shy30) It should also indicate that R2 (external reference) did not have any successful fertilization

325 Need to Acknowledge Additional Uncertainties While the ERA acknowledges some uncertainties associated with the amphibian studies (pp 4-70 4shy73 E-108-110) other critical uncertainties are not acknowledged For example there are uncertainties associated with the concentration-response analysis (eg ECsos ECaos) based on the poor fit of the data in the probit analysis Contrary to the statement that most endpoints followed a fairly smooth concentration-response (text box p 4-60) Table E4-2 indicates that only one of 11 of the ECsos presented (ie Phase III metamorph percent malformed based on comparisons with the lowest vernal pool sediment tPCB concentration) appears to be appropriately described by the probit analysis The other ECsos were described as (a) outside data range confidence limits increase (111) (b) probit model had poor fit to data confidence limits increase (111) (c) calculated with linear interpolation no confidence limits can be calculated (311) and (d) based on visual inspection of data (511) These uncertainties should be recognized

326 Need for Additional Information There are a number of issues on which we urge EPA to provide additional information in the next draft of the ERA

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Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

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Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

Table of Contents Section 1 Introduction 1-1

Section 2 General Comments 2-1

21 Underlying Studies and Data Omitted 2-1 22 Exclusion of Lines of Evidence Prior to the Weight-of-Evidence Evaluations 2-1 23 Overemphasis on Hazard Quotients 2-2

231 Interpretation of HQs 2-2 232 Conservatism of HQs 2-3

2321 Exposure assumptions 2-4 2322 Effects metrics 2-4

24 Exclusion of Data Quality from Weight-of-Evidence Evaluations 2-5 25 Discussion of Evidence Regarding Abundant Populations 2-5 26 Extrapolation across Species and Reaches 2-5

261 Risk Comparisons across Species 2-6 262 Extrapolations to Downstream Reaches 2-6

27 Characterization of GEs Position 2-7 28 Non-PCB Constituents 2-7

Section 3 Specific Comments 3-1

31 Benthic Invertebrates 3-1 311 Concentration-Response Analysis to Derive Sediment Toxicity Thresholds 3-1 312 Effects of Grain Size on Study Interpretation 3-1 313 Use of Sediment Quality Values and Toxicity Identification Evaluation in the

Weight-of-Evidence 3-2 314 Need to Acknowledge Additional Uncertainties 3-2 315 Need for Additional Clarification and Information 3-3

32 Amphibians 3-4 321 Lack of Literature Support for a Toxicity Threshold of 1 mgkg tPCBs in Tissue3-4 322 Lack of Support for a Sediment Toxicity Threshold of 1 mgkg Based on Wood

Frog Study 3-5 323 Need to Consider Additional Relevant Endpoints in Wood Frog Study 3-6 324 Evaluation of the Leopard Frog Study 3-7 325 Need to Acknowledge Additional Uncertainties 3-7 326 Need for Additional Information 3-7 327 Extrapolation of Risks Downstream of the PSA 3-8 328 Error in the Text 3-8

33 Fish 3-8 331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds 3-9 332 Derivation of Literature-Based Toxicity Effects Thresholds 3-9

3321 Lack of basis for tPCB threshold of 14 mgkg 3-9 3322 Lack of basis for TCDDTEQ effects threshold of 43 ngkg 3-11 3323 Consideration of the range of reported effects of tPCBs and TEQs on

fish 3-12 333 Evaluation of Phase I and II Fish Toxicity Studies 3-12

3331 Uncertainty in exposure-response relationships in Phase 1 3-12 3332 Selection of data for development of effect levels from Phase II 3-13

334 Need for More Detailed Information in Appendix F 3-13 3341 Documentation of toxicity thresholds derived from Phase II study 3-13

3342 Documentation of literature-based toxicity thresholds 3-14 335 Consideration of Fish Population Field Studies as Lines of Evidence 3-14 336 Uncertainty Analysis 3-14

34 Insectivorous Birds 3-15 35 Piscivorous and Carnivorous Birds 3-15

351 Concerns Applicable to All Three Species 3-15 3511 Effects metrics 3-15 3512 Presentation of HQs as independent lines of evidence 3-16

352 Robins 3-17 353 Ospreys 3-17

3531 Use of osprey as representative species 3-17 3532 Assumptions applied in HQ 3-18

36 Piscivorous Mammals 3-18 361 Use of Site-Specific Mink Toxicological Assays to Derive Effects Metrics 3-18 362 Apparent Inconsistency in Reported Free Metabolic Rate Slope Term 3-19 363 Newest MinkOtter Survey Data 3-19

37 Omnivorous and Carnivorous Mammals 3-19 371 Calculated Food Ingestion Rates 3-19 372 Effects Metrics 3-19

38 Threatened and Endangered Species 3-19 381 Concerns Applicable to All Receptors Evaluated 3-20 382 Bald Eagles 3-20

3821 Foraging time 3-20 3822 Effects metrics 3-20 3823 Extrapolation of risks downstream of the PSA 3-21

383 American Bitterns 3-22 384 Small-footed Myotis 3-22

Section 4 References 4-1

1 Introduction The General Electric Company (GE) submits these comments to the US Environmental Protection Agency (EPA) on EPAs April 2003 draft of its Ecological Risk Assessment for General Electric (GE)Housatonic River Site Rest of River (hereinafter ERA) These comments were prepared on GEs behalf by BBL Sciences Inc ARCADIS GampM Inc LWB Environmental and Branton Environmental Consulting

GE has many concerns and disagreements with the approaches and inputs used the evaluations provided and the conclusions reached in the ERA However in light of discussions with EPA these comments do not discuss all of GEs concerns and disagreements with the ERA In several prior submissions to EPA GE andor its consultants have presented both general and specific comments on EPAs ERA work plans and on the plans and reports on many of the underlying studies that were performed by EPA contractors and included in the ERA The present comments do not repeat all of those points again Rather the focus of these comments is to provide input to EPA that will improve the ERA prior to the next draft In particular GE has attempted to focus these comments on major issues involving errors or internal inconsistencies in the ERA evaluations or conclusions that we believe are not supported by the evidence and uncertainties that we believe should be more explicitly recognized in the ERA However GE preserves its positions on all issues and points on which it has previously submitted comments to EPA and reserves the right to raise these or any other issues or points in its comments on the ERA during the public comment period andor in its presentations to the Peer Review Panel for the ERA The fact that GE has not raised a particular issue in these comments should not be regarded as agreement to the way in which the ERA has addressed that issue

In addition GE has provided EPA with reports on a number of ecological studies conducted by GE contractors over the past few years which we believe are directly relevant to the ERA Although the current draft ERA mentions these studies it does not discuss them or include them in any of the evaluations or weight-of-evidence analyses in the ERA The current draft notes that these GE studies will be discussed and evaluated in the next draft of the ERA However given the absence of such a discussion or evaluation in the current draft GE is unable to offer comments on EPAs assessment of these studies or how EPAs consideration of them may or should change EPAs overall evaluation or conclusions regarding the receptors involved in these studies In its comments during the public comment period andor in its presentations to the Peer Review Panel GE will provide comments on EPAs discussion evaluation and weighting of these studies in the next draft of the ERA as well as on the implications of these studies for the assessment of potential impacts to local populations and communities of these receptors

These comments are organized as follows Section 2 provides a number of general comments that apply to multiple assessment endpoints or the overall approach used to evaluate risk in this ERA including its overall approach to evaluating the available lines of evidence and implementing the weight-of-evidence analyses and its procedures for extrapolating risks to species and areas that were not studied Section 3 then provides more specific comments on each of the receptor groups considered in the ERA as well as examples of some of the issues raised in Section 2

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2 General Comments A number of general issues apply to multiple assessment endpoints or the overall approach used to evaluate risk in this ERA The general issues discussed below include (a) omission of underlying studies and data (b) exclusion of lines of evidence prior to the weight-of-evidence evaluations (c) overemphasis on hazard quotients (HQs) based on modeled exposures and effects (d) exclusion of data quality from the weight-of-evidence evaluations (e) discussion of evidence regarding abundant populations (f) extrapolations across species and reaches (g) characterization of GEs position and (h) treatment of constituents other than polychlorinated biphenyls (PCBs)

21 Underlying Studies and Data Omitted Neither the reports on the studies that form the basis for many of the measurement endpoints nor the underlying database are provided within or in attachments to the ERA In the absence of the underlying studies and data it is not possible to independently validate calculations statistics or interpretation of those studies EPAs (2002b) Guidelines for Ensuring the Quality Objectivity Utility and Integrity of Information Disseminated by the Environmental Protection Agency emphasize the importance of the reproducibility of such information by qualified third parties (EPA 2002b pp 20-21) GE believes that to ensure the transparency of the ERA the underlying study reports and database should be included as appendices to the ERA (in either paper or electronic form) Through that approach if a commenter or member of the Peer Review Panel wishes to evaluate the underlying basis for a statement or conclusion in the ERA the information necessary to do so will be available

22 Exclusion of Lines of Evidence Prior to the Weight-of-Evidence Evaluations The ERA screens out select lines of evidence (mainly some field studies conducted by EPA contractors) prior to the weight-of-evidence evaluations instead of including all available lines of evidence in the weight-of-evidence evaluations In GEs view this practice is not consistent with the purposes of performing a weight-of-evidence evaluation mdash ie to consider the scientific defensibility of all available lines of evidence to reconcile those lines of evidence and to conclude whether significant risk of harm is posed to the environment (Menzie et al 1996) Moreover this approach does not appear to be systematically applied across receptors For example EPAs fish biomass study is excluded from the weight-of-evidence evaluation on the ground that meaningful statistical assessment of PCS or TEQ relationship to fish community parameters was not feasible (p 5-43) However the qualitative observations of amphibian community structure and the minkotter surveys are (appropriately) included in the weight-of-evidence evaluation despite the fact that like the biomass study statistical evaluations of exposure-response are not possible Additionally the avian surveys are not included in the weight-of-evidence evaluations even though they are initially listed as measurement endpoints for evaluating threatened and endangered species (p 11-6)

GE urges EPA to include all available lines of evidence in the weight-of-evidence evaluations These would include all field-based studies that EPA conducted as well as all studies conducted by GE contractors

In addition for some studies (eg EPAs wood frog study and its Phase II fish toxicity study) the draft ERA includes only a subset of the available endpoints in the weight-of-evidence evaluations as

discussed further in Section 3 In such cases GE urges EPA to evaluate all available and relevant individual lines of evidence from these particular studies

23 Overemphasis on Hazard Quotients The ERA derives Hazard Quotients (HQs) from modeled exposure and effects for the majority of receptors and assesses them as lines of evidence typically according them moderatehigh or high weight In addition the Risk Summary (Section 12) presents the Monte Carlo-based HQs for all receptors to facilitate comparison of risks among aquatic life and wildlife receptors and to give a broad overview of the findings of the risk assessment (p 12-3) Indeed in that section the consideration of other lines of evidence is restricted to a very brief risk characterization that acknowledges that some of the receptors were evaluated based on multiple lines of evidence but does not put the HQs which represent only one of these lines of evidence into this context (pp 12-54 through 12-55) As a result the HQs dominate the presentation of risk in that section

These practices place too much weight and emphasis on the HQs relative to other lines of evidence and tends to obscure the high degree of conservatism and uncertainty associated with the HQs GEs concerns regarding the ERAs interpretation of the HQs and the conservatism and uncertainties present in them are discussed below

231 Interpretation of HQs GE has several concerns with the ERAs interpretation of HQs First in applying the weight-ofshyevidence approach to the HQs the ERA generally does not consider all aspects of the degree of association attribute as defined by Menzie et al (1996) and does not adequately account for limitations in the species-specificity of key input variables Second the HQs are presented in a manner that erroneously suggests that they reflect a full range of individual exposures within the local population Finally the presentation of HQs is confusing in some respects These concerns are further detailed in this section

In applying the weight-of-evidence approach to the HQs the ERA generally assigns moderatehigh or high weight to the great majority of attributes GE believes that a correct application of the Menzie et al (1996) method would yield lower weights for certain of these attributes For example as discussed below the ERA generally scores the HQs moderatehigh or high for the degree of association between the measurement endpoint and the assessment endpoint based primarily on species-specificity whereas GE believes that the HQs should receive low to moderate scores for these attributes

For most of the HQs the rationale provided in the ERA for assignment of a weight related to degree of association refers only to the species-specificity of the study (pp F-52 G-51 H-501-66 J-51 K-68 shyK-69 Tables F4-7 G4-3 H4-314-4 J4-4 K4-3) Based on the Menzie et al (1996) definition as recognized in the ERA (p 2-68) degree of association refers to the extent to which the measurement endpoint is representative of correlated with or applicable to the assessment endpoint in particular with respect to similarity of effect target organ mechanism of action and level of ecological organization (Menzie et al 1996) Hence while species-specificity is part of the definition of degree of association it is not the sole characteristic of that attribute Other aspects of the biological linkage such as the level of ecological organization should also be considered For example EPA guidance states that the assessment endpoints in Superfund ecological risk assessments should address potential

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adverse effects to local populations and communities of biota (EPA 1999 p 5) While that guidance also notes as the ERA states (p 12-47) that impacts on local populations and communities can be estimated by extrapolating from effects on individuals and groups of individuals using a lines-ofshyevidence approach (EPA 1999 p 3) it should be recognized that lines of evidence such as HQ models which do not address population-level effects should receive lower weight in estimating the degree of association with the population-level assessment endpoints Thus GE recommends that the degree of association of each measurement endpoint be evaluated in accordance with the full definition provided by Menzie et al (1996) including consideration of the level of ecological organization

Moreover in evaluating the species-sensitivity aspect of this attribute the ERA does not adequately account for limited species-specificity in the modeled food intake rates fractions of diets derived from the site or effects metrics The food intake rates are calculated using generic allometric equations and input variables that in some cases are not specific to either the preferred prey of the receptor of interest or the receptor itself The assumption that all receptors (except mink) derive 100 of their food from the Primary Study Area (PSA) also does not account for species-specific foraging ranges Although the use of effects metrics based on species in different taxonomic orders from the receptors of interest is recognized in the weight-of-evidence evaluations it only results in scores being reduced from high to moderatehigh A greater decrease in the score is warranted given the significant uncertainties in interspecies extrapolations Hence the most important variables used in the derivation of HQs generally are not species-specific and the weight-of-evidence scores should be lowered on that basis This problem could be ameliorated for some receptors by basing the HQs where possible on site-specific exposure and effects data for the species in question

Further the ERAs presentation of HQ ranges based on distributions of doses (ie lower bound Monte Carlo and upper bound) suggests that the HQs simulate a full range of exposures to individuals within the local population In actuality the upper bound and Monte Carlo HQs presented in the ERA are based on exposures that represent at most a small number of individuals - namely those that derive 100 of their prey from the PSA (except in the case of mink) and only consume prey that contain the highest concentrations of chemicals of potential concern (COPCs) The ERAs use of point estimates for the parameters of proportion of prey derived from the PSA and concentration of COPCs in prey restricts the applicability of the output of the analyses to a very small number of individuals if any to which these exposure parameters might apply As discussed further in Section 2321 below GE recommends use of distributions for these two parameters so that the output of the HQs might be applicable to a broader range of individuals inhabiting the PSA

Finally Figures 122-1 through 122-4 (pp 12-612-912-1112-12) are confusing in that they suggest that absolute values of HQs are comparable across species and across media of interest (eg sediment soil prey) In order to improve the transparency of the risk characterization GE recommends replacing Figures 122-1 through 122-4 with summary tables of the weight-of-evidence evaluations for all assessment endpoints in order to offer a more balanced approach to comparison of risks

232 Conservatism of HQs The ERA states that HQs are not conservative because no safety factors were used to estimate the effects metrics (except in the case of the bald eagle) and uncertainties regarding the exposure model inputs were explicitly propagated through the probability bounds of the exposure model (p 12-10) While GE recognizes that such safety factors are generally not included in the HQ analyses

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considerable conservatism is contributed to the HQs by both the exposure assumptions and the effects metrics If these sources of conservatism are not corrected through alternate assumptions then the conservatism that they contribute should be explicitly acknowledged in the ERA Some of the general sources of conservatism are discussed below while specific comments on the individual receptors are provided in Section 3

2321 Exposure assumptions For all receptors the ERA states that because food intake rates are poorly characterized in the literature it is necessary to model food intake rates based on allometric equations provided in the Wildlife Exposure Factors Handbook (EPA 1993) (eg pp 7-16 8-17 9-13 10-13 11-13) In fact however the EPA (1993) handbook provides measured species-specific food intake rates for all receptor species evaluated in the ERA except tree swallows river otters American bitterns and small-footed myotis According to EPA (1993) measured species-specific values are preferred over modeling intake rates based on allometric equations (p 3-1) GE recommends the use of the species-specific food intake rates reported in the Wildlife Exposure Factors Handbook (EPA 1993) Where that is not or cannot be done the uncertainty associated with using generic allometric equations and input variables that are not species-specific should be discussed and accounted for in the weight-ofshyevidence evaluations

In addition the use of point estimates to characterize the concentrations of COPCs in food and proportion of food derived from the site appears to be inconsistent with the ERAs own criteria for the use of distributions and point estimates The ERA states that point estimates [are used] for minor variables or variables with low coefficients of variation (p 6-17 H-7) Although coefficients of variation are not presented in the ERA and the sensitivity analyses exclude variables characterized with point estimates concentrations of COPCs in food and proportion of diet derived from the site cannot be described as minor because they directly control the magnitude of estimated dose Use of point estimates for these variables prevents uncertainty from being propagated through the probability bounds of the exposure model (p 12-10) and restricts the applicability of the results to those individuals (if any) that only derive their food from the PSA and that always consume food containing the highest concentrations of COPCs In order to align practices applied in the ERA with the stated methodologies GE recommends representation of these variables with appropriate statistical distributions

2322 Effects metrics Many aspects of the effects metrics also contribute to conservatism and uncertainty in the HQs As described in Section 3 these limitations include (for various receptors) the absence of clear documentation of the practices employed in development of the effects metrics lack of support by the underlying studies or failure to reflect the full body of toxicological literature andor lack of acknowledgment of important sources of uncertainty GE recommends revision of the effects metrics in the ERA as discussed in Section 3

The ERA (eg p 6-20) also states that in all cases effects metrics were consistent with the metrics used in the exposure analysis However the ways in which they are consistent are not defined While the effects metrics and exposure analyses are consistent with respect to units (eg mgkg-day) in many cases they are inconsistent with respect to species exposure duration and dosing regime For example an effect metric based on a domesticated species (ie white leghorn chickens) cannot be

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considered consistent with exposure metrics for wild avian receptors GE recommends revising the above statement so that it specifies the ways in which effects metrics are consistent with exposure metrics GE also recommends that the weight-of-evidence evaluations be modified to account for inconsistencies with respect to species exposure duration and dosing regime

24 Exclusion of Data Quality from Weight-of-Evidence Evaluations Based on Menzie et als (1996) quantitative weight-of-evidence approach data quality is one of the most important attributes in determining the scientific defensibility of a measurement endpoint Nonetheless the ERA does not include data quality as an attribute in the weight-of-evidence evaluations Instead the ERA asserts that all studies used in the ERA (except those conducted by GE contractors) have adequate data quality (p 2-70) However the criteria for determining the adequacy of data quality are not defined the process and outcome of a data quality evaluation are not provided and the underlying studies and data are not provided Consequently it is not possible to verify the validity of the assumption that all data have adequate quality In addition this approach implies that data quality for all measurement endpoints based on EPAs studies are equal In fact data quality varies considerably among the underlying studies For example errors and inconsistencies in the databases and analyses presented in underlying studies were identified in comments that GE has previously submitted to EPA The exclusion of data quality from the weight-of-evidence evaluation prevents EPA from accounting for those differences hi data quality

For these reasons GE urges EPA to modify the ERA so that it (a) specifies all necessary information to allow an independent evaluation of data quality for each measurement endpoint (b) includes the attribute of data quality in the weight-of-evidence evaluations and (c) acknowledges any data quality limitations

25 Discussion of Evidence Regarding Abundant Populations Section 12322 of the ERA lists a number of factors that it asserts indicate that studies showing an abundant population of a given receptor at the site do not demonstrate a lack of adverse effects on that population (pp 12-48 through 12-50) The ERA claims that (a) removal of predators compensates for direct effects of contaminants (b) immigration compensates for direct effects of contaminants (c) populations exposed to COPCs may be more vulnerable to other stressors in the future due to chemical adaptation andor immune system effects The application of these theories to a specific site such as the PSA is speculative and unsupported by the underlying studies None of the studies discussed in the ERA was designed to evaluate these types of effects GE believes that this entire discussion should be deleted from the ERA as speculative and unsupported by the data

26 Extrapolation across Species and Reaches The ERA extrapolates findings for risks posed to individual receptors within the PSA to other species and to areas outside the PSA There are several limitations associated with these practices as discussed below

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261 Risk Comparisons across Species The ERA qualitatively extrapolates predicted risks for each receptor to other species within the same feeding guild based on factors that influence exposure to COPCs (eg diet foraging range body weight) There are a number of problems with this approach First in the absence of data on the other species these extrapolations are not supported by any actual evidence Second these extrapolations of risk do not recognize that risk is a function not only of exposure but also of toxicological sensitivity By making the extrapolations based on factors that relate solely to exposure the ERA implies that all species within a feeding guild are equally sensitive to the toxicological effects of the COPCs However as demonstrated by Brunstrom and Lund (1988) toxicological sensitivity can vary by orders of magnitude across species even for species in the same feeding guild and taxonomic order (eg chickens and turkeys) Hence these analyses should not be referred to as comparisons of risk

The interspecies extrapolations also do not account for field data that either support or refute qualitative conclusions regarding relative risks For example data collected by the Massachusetts Division of Fisheries and Wildlife since 1980 on the productivity of great blue herons throughout Massachusetts show no differences in the numbers of young per nest for herons breeding within or beyond foraging distance of the PSA (MDFW 1979 1980 1981 1982 1983 1984 1985 1986ab 1987 1989 1991 1996) This finding does not support the ERAs qualitative finding that great blue herons face similar to higher risks than American bitterns which are predicted to have high risks (p 12-36)

GE recommends that extrapolations of risk estimates from receptors of interest to other species be omitted from the ERA because they are too uncertain to provide useful information If they are retained GE recommends that the comparisons be accurately characterized as comparisons of potential exposure rather than as comparisons of risk Regardless of how the extrapolations are presented however uncertainties should be explicitly reported including both the inability of the analysis to account for interspecies differences in toxicological sensitivity and cases where available field data contradict the extrapolated findings

262 Extrapolations to Downstream Reaches The field studies surveys and sampling program conducted for the ERA primarily focus on the PSA In an effort to apply the analyses across the entire study area the ERA extrapolates risks downstream of the PSA for seven receptors (benthic invertebrates amphibians warm water fish trout mink otter and bald eagles) For each of these groups the ERA identifies a maximum acceptable threshold concentration (MATC) for total PCBs (tPCBs) Each MATC is then compared to exposure concentrations for individual river and floodplain reaches downstream of Woods Pond to Long Island Sound Areas where exposure concentrations exceed the MATCs are interpreted as indicating potential risks

GE recommends several improvements in this approach (a) revision of the MATCs (b) improved spatial resolution of the overlap between predictions of risk to each receptor and the availability of suitable habitat for those receptors and (c) an explicit discussion of the uncertainties associated with these extrapolations In addition more complete documentation of the methodologies and assumptions employed would enhance the transparency of the analysis

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First several of the MATCs (eg for benthic invertebrates amphibians fish and bald eagles) are not supported by the site-specific studies or the scientific literature Specific concerns related to the basis for these MATCs are discussed below in Sections 311 (benthic invertebrates) 321 amp 322 (amphibians) 332 amp 333 (fish) and 3822 (bald eagles) GE recommends that these MATCs be revised

Second the applicability of the benchmark comparisons for each of the seven receptors should also be considered relative to the available habitat for such receptors in the downstream reaches For example although the MATC for amphibians was developed based on sediment tPCB concentrations in breeding ponds it was applied downstream of Woods Pond to soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data in the downstream reaches (p 12-15) Although such data may be lacking the ERA should make clear that the extrapolation applies only to sediment in potential floodplain ponds downstream of Woods Pond In addition risks to mink otters and bald eagles are evaluated for all reaches of the river with adequate data on exposure concentrations regardless of habitat Restricting the assessment of risks for these receptors to those reaches with suitable habitat would further improve the accuracy of these extrapolations

Third uncertainties in the extrapolations should be discussed and the results should be subjected to a separate weight-of-evidence evaluation

Finally the ERA does not provide enough information regarding the actual methodologies and assumptions used in the analysis of risks downstream of Woods Pond Transparency in this analysis is of paramount importance given the potential influence and use of these extrapolated risk results In particular the ERA should report the actual exposure concentrations used and whether they are spatially weighted averages arithmetic averages 95 upper confidence limits (UCLs) maxima etc In addition EPA should provide at least general information regarding the suitability of the downstream habitat for these receptors or where such information does not exist acknowledge that habitat has not been evaluated and could have a significant effect on any risks downstream of Woods Pond

27 Characterization of GEs Position In several places (pp 2-60 2-61) the ERA characterizes GEs position GE requests that such descriptions of GEs position be removed from the ERA GE will present its position in its comments during the public comment period andor to the Peer Review Panel

28 Non-PCB Constituents The ERA covers the Rest of River which is defined in the Consent Decree (Paragraph 6) as the Housatonic River and its sediments and floodplain areas downstream of the Confluence of the East and West Branches of the Housatonic River including backwaters except for ActualPotential Lawns to the extent that such areas are areas to which Waste Materials that originated at the GE Plant Area have migrated and which are being investigated or remediated pursuant to this Consent Decree (emphasis added) The Revised RCRA Permit contains a similar definition (Definition 19) limiting the Rest of River areas to areas to which releases of hazardous wastes andor hazardous constituents are migrating or have migrated from the GE Facility

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The ERA recognizes that the Rest of River includes areas of the Housatonic River and its sediments and floodplain (except ActualPotential Lawns) in which contaminants migrating from the GE facility are located (p 1-2) However it includes as COPCs a number of non-PCB constituents that are or may not be related to releases from the GE facility These include for various media numerous polycyclic aromatic hydrocarbons (PAHs) and other semi-volatile organic compounds (SVOCs) dioxins and furans several metals and (for fish) certain pesticides (Tables 24-2 through 24-5) There are multiple potential sources of these constituents in the Rest of River area not just releases from the GE facility

To avoid any confusion the ERA should make clear in its discussions of the COPCs (Sections 231 and 243) that while several COPCs other than PCBs have been selected for the ERA there are multiple potential sources of these constituents and hence there is no evidence demonstrating that the occurrence of these COPCs in the Rest of River area is necessarily derived from releases attributable to GE

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3 Specific Comments

31 Benthic Invertebrates In its assessment of benthic invertebrates the ERA derives toxicity thresholds (MATCs) of 3 mgkg tPCB in both tissue (based on the literature) and sediments (based on the results of toxicity and benthic community studies) GE believes that these thresholds should be reevaluated As discussed in this section GE urges EPA to make the following changes to the ERAs assessment of benthic invertebrates (a) use a different data set to calculate sediment-based toxicity thresholds (b) take adequate account of sediment grain size in interpreting the benthic community and toxicity test results (c) reduce the emphasis on Sediment Quality Values and the Toxicity Identification Evaluation (TIE) results (d) recognize a number of additional specified uncertainties and (e) clarify or provide additional information on certain issues

311 Concentration-Response Analysis to Derive Sediment Toxicity Thresholds The ERA concludes that the toxicity studies showed ecologically significant effects at sediment tPCB concentrations of 3 mgkg or higher (pp 3-71 D-98) the proposed MATC for sediment This proposed toxicity threshold is apparently based on LCso and ICso values from laboratory studies that were calculated based on the median values of multiple grab samples (p D-10) (some of which were collected independently of the laboratory bioassays) rather than based on measured concentrations of PCBs in sediments actually used in these bioassays The use of these unrelated data as a basis for establishing exposure levels in laboratory bioassays is of concern given that PCB concentrations in sediments of the Housatonic River can vary by orders of magnitude over very small spatial and temporal scales (pp D-26 to D-28) The rationale given for this method is that combining data from sampling events that are approximately (but not exactly) synoptic with the effects data more accurately portrays the COC concentrations at each station (p D-27) This approach may provide an indication of PCB concentrations in the vicinity of a station over time but it does not provide a better measure of PCB concentrations in the specific composites used in the bioassays than would a direct measure of PCBs in the sediments used in the bioassays For some stations concentrations measured directly from the composites are in fact substantially different than those derived from other collection efforts (Figures D3-1 through D3-5 Stations 7 and 8A) resulting in variability which likely substantially affects the exposure-response analyses and resulting LCsos and ICsoS Because of this variability it is important that effects levels for bioassay tests be calculated from the data that represent the concentrations to which these organisms were actually exposed

GE recommends that the ERA be revised to calculate the No Observed Adverse Effect Levels (NOAELs) Lowest Observed Adverse Effect Levels (LOAELs) and LCsoICso values for the laboratory bioassays (Tables D4-2 and D4-3) based on the synoptic values derived directly from the composite samples for the laboratory bioassays because these values best represent the exposures to the test organisms The LCao and IC20 values should also be revised in a similar manner as should the linear regression models (Table D4-4 Figure D4-5)

312 Effects of Grain Size on Study Interpretation Grain size is a significant variable that can impact both benthic community structure and the endpoints evaluated in the laboratory toxicity studies However in several instances the ERA does not adequately consider the effects of grain size in interpreting the study results

The ERA states that the benthic community data indicated that five of the six stations with median tPCB concentrations above 5 mgkg had significant benthic community alteration (p D-98) Those same five stations had coarse-grained sediments (see Figures D4-6 and D4-7) The one fine-grained station with median tPCB concentrations greater than 5 mgkg (Station 8) had higher species richness and abundance than the coarse-grained stations and was not significantly different from the reference stations (see Figures D4-6 D4-7 and D4-15) Benthic invertebrates tend to be the least diverse and the least abundant in sand likely due to its instability (Ward 1992 Minshall 1984 Allan 1995) Thus even in the absence of PCBs the diversity and abundance of invertebrates would be expected to be lower at the coarse-grained stations In these circumstances it is at least equally likely that grain size rather than PCB concentration explains the spatial variations in benthic community structure As a result the statements throughout the ERA regarding the high level of confidence in the conclusion that benthic invertebrates in the Housatonic River experience unacceptable risks due to tPCBs (eg p 12-55) are not be supported Those statements should be revised to recognize the confounding impacts and uncertainty associated with grain size effects and to note that as a result the benthic community data do not provide conclusive evidence of tPCB effects on changes in community structure

Similar concerns apply to the bioassay test The reference stations used in the bioassay test (Al and A3) are coarse-grained (Figure D2-2) whereas the treatment stations showing the highest levels of response (Stations 7 8 and 8A) are fine-grained Statistical analyses and the weight of evidence evaluation are based on comparisons made between Housatonic River sediment stations and references regardless of grain size (Table D3-4 and Figure D4-15) The uncertainty associated with comparing the toxicity of fine-grained stations to coarse-grained reference treatments should be acknowledged

313 Use of Sediment Quality Values and Toxicity Identification Evaluation in the Weight-of-Evidence

The ERA also relies on published Sediment Quality Values (SQVs) to support a sediment toxicity threshold value of 3 to 5 mgkg (pp 3-71 D-98) SQVs are generic in nature and therefore are primarily appropriate in screening-level ERAs when no site-specific data are available (see eg Long et al 1995) Given the availability of substantial site-specific data the generic SQVs should not be used at all or at a minimum given very low weight and the references to them should be removed from the conclusions

The ERA also gives moderate weight to the results of the Toxicity Identification Evaluation (TIE) (Table D4-5) The ERA concludes from this Phase I TIE that PCBs may be the main causal agent in the toxicity studies (p D-78) However the TIE was not a definitive study and was not designed to provide an independent evaluation of effects and the results of the TIE are inconclusive showing only that non-polar organic chemicals were likely responsible for the observed toxicity As a result while the results of the TIE provide some evidence as to the degree to which observed effects can be linked to PCBs rather than other COPCs the TIE study should be removed as a separate line of evidence

314 Need to Acknowledge Additional Uncertainties There are a number of uncertainties associated with the benthic invertebrate studies Some of these are acknowledged in the text (pp D-95 through D-98) but other critical uncertainties are not The text should be revised to acknowledge the following uncertainties

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Lack of concordance between benthic community and sediment toxicity study results At the four stations for which there are both sediment toxicity test data and benthic community data those results are contradictory The sediment toxicity tests show a toxic response for most endpoints (especially at Stations 7 and 8) whereas the benthic community analyses do not (see Figure D4-15) GE recommends that the ERA be revised to discuss this point in the uncertainty section and also to carry this through to the conclusions in terms of the ability to extrapolate the potential for adverse effects to downstream locations

Inconsistent patterns oftPCB concentrations in sediment and tissues The ERA likewise does not discuss the fact that the median tPCB concentrations in sediments and those in tissue are not consistent (eg elevated tPCB concentrations in sediments were not co-located with those in tissue) (compare Figure 33-3 on p 3-18 with Figure 33-6 on p 3-22) These inconsistencies raise questions regarding the reliability of using median sediment concentrations as a measure of exposure for benthic invertebrates They also limit the usefulness of the biota sediment accumulation factors (BSAFs) which range from 08 to 61 (p D-32) in predicting tissue levels from sediment concentrations These inconsistencies should be acknowledged in the discussion of tissue chemistry (Section 335 pp 3-21 and 3-23) and the implications relative to estimating exposure should be addressed in the uncertainty section

Calculation of LC$o and ICso values The toxicity test endpoints presented in Tables D4-1 through D4-3 based on statistical analyses have a number of significant uncertainties Specifically uncertainties are associated with the results in which (a) the chi-square value exceeds the critical value in the derivation of LCjos and LC2os (20 out of 54 endpoints) (b) visual observations rather than the probit analyses were used because the model did not converge (2 out of 54 endpoints) and (c) there was an interrupted dose-response (9 of 54 endpoints) These difficulties with the statistical analyses are indicative of inconsistencies in the dose-response relationships that result in uncertainty surrounding the threshold values These uncertainties should be addressed (Tables D4-1 - D4-3) In addition no explanation is provided for why the highest dose (772 mgkg) for H azteca 48-h survival is excluded from the effects threshold analysis (Table D4-1) Additional information should be included regarding its exclusion or the analyses should be redone using the results of this treatment

Use of single samples to characterize sediment in used in bioassays A discussion of the uncertainty associated with determining exposure values of sediment composites used in toxicity testing based on a single chemistry sample should be provided (p D-17) Alternatively if multiple samples were used to evaluate potential heterogeneity in these composites to confirm that sediment was completely mixed then those data should be provided

315 Need for Additional Clarification and Information This section describes a number of issues for which the next draft of the ERA should provide clarification or additional data or analyses

Tissue effects thresholds from the literature The ERA states that the literature review was focused on Aroclor 1260 and 1254 (p 3-14) It should be revised to state that no effects thresholds were found based on studies with Aroclor 1260 and that only studies of tPCBs Aroclor 1254 and Clophen A50 were used to derive these thresholds The figures summarizing the literature effects thresholds should also be revised to indicate which study is associated with the effects reported (eg in Figure 44-13)

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and to indicate that studies with Clophen A50 are included in the summary In addition congenershyspecific studies should be removed from the literature review (Table D3-5 and Attachment DI) as they are not appropriate surrogates for tPCB toxicity

Multi-dimensional scaling analysis The results of the multi-dimensional scaling (MDS) statistical analyses used to develop Figures D3-15 through D3-17 should be presented This will provide important information regarding the relative contribution of different factors in this multivariate analysis

Derivation of MATCs The ERA does not explain explicitly how the sediment MATC of 3 mgkg tPCB (p 3-72) used to assess the extent of risks downstream from the PSA was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should specifically document the derivation of the MATC value used

32 Amphibians In the assessment of amphibians the ERA derives toxicity thresholds (MATCs) of 1 mgkg in both tissue (based on the literature) and sediments (based on the results of EPAs wood frog study) As discussed below GE believes that neither of these thresholds is supported by the underlying studies and that they should be higher Moreover in evaluating the results of the wood frog study the ERA does not consider certain endpoints (metamorphosis and mortality) that have clear ecological relevance these endpoints should be included in the evaluation In addition as further discussed in these comments we urge EPA to (a) give lower weight to the results of the leopard frog study and explicitly recognize its use of external reference frogs (b) recognize additional specified uncertainties in the amphibian assessment (c) clarify or present additional data or analyses on certain issues (d) modify the extrapolation to reaches downstream of Woods Pond and (e) correct an error in the text1

321 Lack of Literature Support for a Toxicity Threshold of 1 mgkg tPCBs in Tissue The ERA specifies a toxicity threshold of 1 mgkg in tissue based on a review of the literature (pp 4shy75 E-96) The studies and results used in this review are summarized in Figures 44-13 and E3-37 However the two tPCB LOAELs (called LOELs in these figures) below 1 mgkg shown in these figures are not supported by the underlying study (Gutleb et al 2000) One of these effects levels for time to metamorphosis for the African clawed frog is based on exposure to PCB 126 although tissue chemistry was analyzed as tPCBs Comparing tPCB concentrations to effects levels from a study in which larvae were exposed to PCB 126 would substantially overstate tPCB toxicity and hence this effect level should not be used to evaluate potential tPCB effects The second LOAEL for the European common frog is 024 mgkg tPCBs (wet weight2) in tissue (based on exposure to Clophen A50) However at that concentration there was no adverse effect body weight in the exposed frogs was higher not lower than in the control frogs In fact there was no significant effect on body weight at the highest tissue concentration used in this study (112 mgkg tPCBs wet weight) Hence the latter

1 As noted in Section 1 EPA has also agreed to include the frog study sponsored by GE (Resetarits 2002) in the next draft of the ERA In addition GE has recently completed a study of leopard frog egg masses in the PSA and is providing a report on that study to EPA (ARCADIS 2003) That study should likewise be included in the next draft of the ERA

2 As converted from lipid weight in Attachment E2

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value should be reported as an unbounded NOAEL for that endpoint and the value reported as a LOAEL (024 mgkg) should be removed from these figures

Additional concerns associated with the summary of the literature effects are related to the interpretation of the frequency of occurrence of adverse effects (p 4-56 and E-81) First three LOAELs are cited for mortality based on a single experiment (Savage et al 2002) (Figure 4431 p 4shy57 and E3-37 p 60) By definition a LOAEL is the lowest concentration in an experiment for which there is a statistically significant difference relative to the control therefore only the LOAEL at approximately 6 mgkg from this study should be included in this figure When the erroneous LOAEL (Gutleb et al 2000) and the redundant LOAELs (Savage et al 2002) are removed the frequency of adverse effect analysis indicates that 4 out of 12 endpoints (for tPCBs) or 33 demonstrate adverse effects at concentrations greater than 1 mgkg and that in fact no adverse effects are observed below 6 mgkg

In addition the meaning of this frequency of adverse effects is not clear because there are substantive differences between the nature of effects observed For example the endpoints of reduced activity or swimming speed may or may not have the same severity of impact to an individual as increased mortality This distinction is lost in a simple evaluation of frequency of effects between different endpoints in various literature studies

Based on the above discussion the statement that [tjhere were six instances of adverse effects occurring between 1 and 10 mgkg (pp 4-56 and E-81) should be revised For tPCBs there are only three LOAELs (ie incidence of adverse effects) between 1 and 10 mgkg and all them are at or above 6 mgkg The text should be revised accordingly If the interpretation of these studies based on the frequency of adverse effects is retained that text should also be revised and uncertainties associated with direct comparisons of the different kinds of effects included in this analysis should be acknowledged

322 Lack of Support for a Sediment Toxicity Threshold of 1 mgkg Based on Wood Frog Study

The sediment toxicity threshold of 1 mgkg is apparently based primarily on an analysis of the results of EPAs wood frog study However the description of the results of that study states that [e]cologically significant adverse effects in late stage juvenile wood frogs occurred in the sediment tPCB concentration range of 10 to 60 mgkg although responses of lesser magnitude yet statistically significant were observed at 5 mgkg tPCB and lower (p 4-60) The latter statement (which may be the basis for the threshold) is apparently derived from the wood frog NOAELs and LOAELs presented in Table E4-2 However there are several problems or inconsistencies in the derivation of site-specific NOAELs and LOAELs presented in Table E4-2

bull In several instances the NOAELs and LOAELs do not coincide with sediment concentrations that are associated with the effects data For example the spatially weighted mean tPCB value of 136 mgkg is presented as either a NOAEL or LOAEL for all four endpoints in Table E4-2 However it appears that this value is associated with a vernal pool (46-VP-4 Table E2-8) that has no effects data associated with it (see Tables E3-5- E3-6 and E 310 - E3-11)

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bull It appears that the reference WML-1 has been excluded from the calculation of NOAELs and LOAELs for Phase III metamorphs because of zero response at this concentration(Table E4-2) This exclusion is not warranted While the text refers to the tissue tPCB concentration for reference location WML-1 in the Phase III of the wood frog study as anomalous (eg p 4-52) no problems with data quality are reported that would indicate that the organism did not in fact have a tissue burden of 44 mgkg tPCBs As a result responses associated with this exposure level should be considered to represent part of the range of effects and all analyses of exposure and effect should include this reference site Statistical comparisons with a zero value are commonly made using a value marginally greater than zero (eg 000001)

bull Concentration-response relationships for each endpoint were evaluated using both (1) the most synoptic chemistry value paired with each toxicity endpoint (also referred to as vernal pool sediment) and (2) a combined data set used to generate a spatially weighted surface average (pp 4shy16 mdash 4-17) Given the variability in sediment concentrations the samples used in the laboratory toxicity study should not be assumed to be equivalent to the surface weighted average The synoptic (ie vernal pool) data reflect the actual tPCB concentrations measured in sediments used in the laboratory exposures and should thus should be used for analyses of the Phase I wood frog study which was conducted in the laboratory The surface weighted averages should be used for the analysis of Phase II and Phase III studies in which larvae and metamorphs were exposed in the field as they encompass the range of concentrations to which the growing larvae and metamorphs might have been exposed to The NOAELs LOAELs and point estimates for effects concentrations (eg LC50 and LC20) (Table E4-2) should be revised accordingly

bull Table E4-2 states that the reference site had no malformed specimens (Phase II metamorphs percent malformed) In fact Table E3-11 indicates that reference site WML-3 had 29 malformations

Moreover the toxicity threshold for wood frogs was derived based only on endpoints that showed effects The ERA states that if no discern[i]ble differences in effect levels across treatments were observed (ie inadequate range in response variable) the effects endpoint was not considered in the detailed statistical evaluation (p E-90) As a result as discussed in the next section the lack of PCB-related effects for key endpoints (ie mortality and metamorphosis) were not considered in the derivation of the effects threshold Consideration of the results for those omitted endpoints shows further that the sediment MATC of 1 mgkg is too low

We also note that although Appendix E presents tissue-based HQs for leopard frogs and wood frogs (pp E-96 - E-98) Section 12 of the ERA presents only sediment-based HQs (Figures 122-1 and p 12shy7) Tissue concentrations provide a more direct measure of exposure than do sediment concentrations and hence the tissue-based rather than sediment-based HQs should be used in Section 12

323 Need to Consider Additional Relevant Endpoints in Wood Frog Study As noted above in evaluating the results of the wood frog study two endpoints with clear ecological relevance ~ metamorphosis and mortality -- were screened out of the formal concentration-response modeling due to a lack of discern[i]ble differences in effect levels across treatments (p E-90) However these two endpoints integrate other effects (ie the most serious effect of malformations would be reduced metamorphosis and increased mortality) and should be carried through the

concentration-response evaluation If no concentration-response curve can be derived because there were no effects then the highest dose should be treated as a NOAEL for these endpoints the LC50

should be expressed as gt highest dose and both mortality and metamorphosis should be considered subsequently as part of the lines-of-evidence evaluation

324 Evaluation of the Leopard Frog Study EPAs leopard frog study receives the same overall weight (moderatehigh) as its wood frog study in the weight-of evidence-evaluation (Table 45-4 p 4-69) Considering the significant problems with the leopard frog study as detailed in GEs comments on this study (BBL Sciences et al 2003a) it should be accorded a low weight

Moreover the text does not consistently acknowledge that reference frogs for the leopard frog study were obtained from a biological supply company For readers unfamiliar with the underlying study this could lead to misinterpretations of the results presented The text should be modified to clearly represent this aspect of the leopard frog study as well as additional qualifications as follows

bull The first time the study design of the leopard frog study is presented it should be clearly stated that no frogs or eggslarvae were found in the reference areas (p 4-13)

bull The text that describes comparisons between both the toxicity studies and the community evaluations and appropriately matched field references (p 4-27) should be revised to indicate that for the leopard frog study the field reference was limited to sediment not frogs collected from a reference pond

bull Although the text states that reference ponds were surveyed for eggs and larvae it does not indicate that in addition to no eggs or larvae being found at four of nine contaminated sites none were found at the reference sites (p 4-35)

bull Similarly the summary of female leopard frog reproductive fitness identifies all of the Housatonic River sites that were not gravid (did not have eggs mature enough for successful fertilization) (p 4shy30) It should also indicate that R2 (external reference) did not have any successful fertilization

325 Need to Acknowledge Additional Uncertainties While the ERA acknowledges some uncertainties associated with the amphibian studies (pp 4-70 4shy73 E-108-110) other critical uncertainties are not acknowledged For example there are uncertainties associated with the concentration-response analysis (eg ECsos ECaos) based on the poor fit of the data in the probit analysis Contrary to the statement that most endpoints followed a fairly smooth concentration-response (text box p 4-60) Table E4-2 indicates that only one of 11 of the ECsos presented (ie Phase III metamorph percent malformed based on comparisons with the lowest vernal pool sediment tPCB concentration) appears to be appropriately described by the probit analysis The other ECsos were described as (a) outside data range confidence limits increase (111) (b) probit model had poor fit to data confidence limits increase (111) (c) calculated with linear interpolation no confidence limits can be calculated (311) and (d) based on visual inspection of data (511) These uncertainties should be recognized

326 Need for Additional Information There are a number of issues on which we urge EPA to provide additional information in the next draft of the ERA

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Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

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Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

3342 Documentation of literature-based toxicity thresholds 3-14 335 Consideration of Fish Population Field Studies as Lines of Evidence 3-14 336 Uncertainty Analysis 3-14

34 Insectivorous Birds 3-15 35 Piscivorous and Carnivorous Birds 3-15

351 Concerns Applicable to All Three Species 3-15 3511 Effects metrics 3-15 3512 Presentation of HQs as independent lines of evidence 3-16

352 Robins 3-17 353 Ospreys 3-17

3531 Use of osprey as representative species 3-17 3532 Assumptions applied in HQ 3-18

36 Piscivorous Mammals 3-18 361 Use of Site-Specific Mink Toxicological Assays to Derive Effects Metrics 3-18 362 Apparent Inconsistency in Reported Free Metabolic Rate Slope Term 3-19 363 Newest MinkOtter Survey Data 3-19

37 Omnivorous and Carnivorous Mammals 3-19 371 Calculated Food Ingestion Rates 3-19 372 Effects Metrics 3-19

38 Threatened and Endangered Species 3-19 381 Concerns Applicable to All Receptors Evaluated 3-20 382 Bald Eagles 3-20

3821 Foraging time 3-20 3822 Effects metrics 3-20 3823 Extrapolation of risks downstream of the PSA 3-21

383 American Bitterns 3-22 384 Small-footed Myotis 3-22

Section 4 References 4-1

1 Introduction The General Electric Company (GE) submits these comments to the US Environmental Protection Agency (EPA) on EPAs April 2003 draft of its Ecological Risk Assessment for General Electric (GE)Housatonic River Site Rest of River (hereinafter ERA) These comments were prepared on GEs behalf by BBL Sciences Inc ARCADIS GampM Inc LWB Environmental and Branton Environmental Consulting

GE has many concerns and disagreements with the approaches and inputs used the evaluations provided and the conclusions reached in the ERA However in light of discussions with EPA these comments do not discuss all of GEs concerns and disagreements with the ERA In several prior submissions to EPA GE andor its consultants have presented both general and specific comments on EPAs ERA work plans and on the plans and reports on many of the underlying studies that were performed by EPA contractors and included in the ERA The present comments do not repeat all of those points again Rather the focus of these comments is to provide input to EPA that will improve the ERA prior to the next draft In particular GE has attempted to focus these comments on major issues involving errors or internal inconsistencies in the ERA evaluations or conclusions that we believe are not supported by the evidence and uncertainties that we believe should be more explicitly recognized in the ERA However GE preserves its positions on all issues and points on which it has previously submitted comments to EPA and reserves the right to raise these or any other issues or points in its comments on the ERA during the public comment period andor in its presentations to the Peer Review Panel for the ERA The fact that GE has not raised a particular issue in these comments should not be regarded as agreement to the way in which the ERA has addressed that issue

In addition GE has provided EPA with reports on a number of ecological studies conducted by GE contractors over the past few years which we believe are directly relevant to the ERA Although the current draft ERA mentions these studies it does not discuss them or include them in any of the evaluations or weight-of-evidence analyses in the ERA The current draft notes that these GE studies will be discussed and evaluated in the next draft of the ERA However given the absence of such a discussion or evaluation in the current draft GE is unable to offer comments on EPAs assessment of these studies or how EPAs consideration of them may or should change EPAs overall evaluation or conclusions regarding the receptors involved in these studies In its comments during the public comment period andor in its presentations to the Peer Review Panel GE will provide comments on EPAs discussion evaluation and weighting of these studies in the next draft of the ERA as well as on the implications of these studies for the assessment of potential impacts to local populations and communities of these receptors

These comments are organized as follows Section 2 provides a number of general comments that apply to multiple assessment endpoints or the overall approach used to evaluate risk in this ERA including its overall approach to evaluating the available lines of evidence and implementing the weight-of-evidence analyses and its procedures for extrapolating risks to species and areas that were not studied Section 3 then provides more specific comments on each of the receptor groups considered in the ERA as well as examples of some of the issues raised in Section 2

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2 General Comments A number of general issues apply to multiple assessment endpoints or the overall approach used to evaluate risk in this ERA The general issues discussed below include (a) omission of underlying studies and data (b) exclusion of lines of evidence prior to the weight-of-evidence evaluations (c) overemphasis on hazard quotients (HQs) based on modeled exposures and effects (d) exclusion of data quality from the weight-of-evidence evaluations (e) discussion of evidence regarding abundant populations (f) extrapolations across species and reaches (g) characterization of GEs position and (h) treatment of constituents other than polychlorinated biphenyls (PCBs)

21 Underlying Studies and Data Omitted Neither the reports on the studies that form the basis for many of the measurement endpoints nor the underlying database are provided within or in attachments to the ERA In the absence of the underlying studies and data it is not possible to independently validate calculations statistics or interpretation of those studies EPAs (2002b) Guidelines for Ensuring the Quality Objectivity Utility and Integrity of Information Disseminated by the Environmental Protection Agency emphasize the importance of the reproducibility of such information by qualified third parties (EPA 2002b pp 20-21) GE believes that to ensure the transparency of the ERA the underlying study reports and database should be included as appendices to the ERA (in either paper or electronic form) Through that approach if a commenter or member of the Peer Review Panel wishes to evaluate the underlying basis for a statement or conclusion in the ERA the information necessary to do so will be available

22 Exclusion of Lines of Evidence Prior to the Weight-of-Evidence Evaluations The ERA screens out select lines of evidence (mainly some field studies conducted by EPA contractors) prior to the weight-of-evidence evaluations instead of including all available lines of evidence in the weight-of-evidence evaluations In GEs view this practice is not consistent with the purposes of performing a weight-of-evidence evaluation mdash ie to consider the scientific defensibility of all available lines of evidence to reconcile those lines of evidence and to conclude whether significant risk of harm is posed to the environment (Menzie et al 1996) Moreover this approach does not appear to be systematically applied across receptors For example EPAs fish biomass study is excluded from the weight-of-evidence evaluation on the ground that meaningful statistical assessment of PCS or TEQ relationship to fish community parameters was not feasible (p 5-43) However the qualitative observations of amphibian community structure and the minkotter surveys are (appropriately) included in the weight-of-evidence evaluation despite the fact that like the biomass study statistical evaluations of exposure-response are not possible Additionally the avian surveys are not included in the weight-of-evidence evaluations even though they are initially listed as measurement endpoints for evaluating threatened and endangered species (p 11-6)

GE urges EPA to include all available lines of evidence in the weight-of-evidence evaluations These would include all field-based studies that EPA conducted as well as all studies conducted by GE contractors

In addition for some studies (eg EPAs wood frog study and its Phase II fish toxicity study) the draft ERA includes only a subset of the available endpoints in the weight-of-evidence evaluations as

discussed further in Section 3 In such cases GE urges EPA to evaluate all available and relevant individual lines of evidence from these particular studies

23 Overemphasis on Hazard Quotients The ERA derives Hazard Quotients (HQs) from modeled exposure and effects for the majority of receptors and assesses them as lines of evidence typically according them moderatehigh or high weight In addition the Risk Summary (Section 12) presents the Monte Carlo-based HQs for all receptors to facilitate comparison of risks among aquatic life and wildlife receptors and to give a broad overview of the findings of the risk assessment (p 12-3) Indeed in that section the consideration of other lines of evidence is restricted to a very brief risk characterization that acknowledges that some of the receptors were evaluated based on multiple lines of evidence but does not put the HQs which represent only one of these lines of evidence into this context (pp 12-54 through 12-55) As a result the HQs dominate the presentation of risk in that section

These practices place too much weight and emphasis on the HQs relative to other lines of evidence and tends to obscure the high degree of conservatism and uncertainty associated with the HQs GEs concerns regarding the ERAs interpretation of the HQs and the conservatism and uncertainties present in them are discussed below

231 Interpretation of HQs GE has several concerns with the ERAs interpretation of HQs First in applying the weight-ofshyevidence approach to the HQs the ERA generally does not consider all aspects of the degree of association attribute as defined by Menzie et al (1996) and does not adequately account for limitations in the species-specificity of key input variables Second the HQs are presented in a manner that erroneously suggests that they reflect a full range of individual exposures within the local population Finally the presentation of HQs is confusing in some respects These concerns are further detailed in this section

In applying the weight-of-evidence approach to the HQs the ERA generally assigns moderatehigh or high weight to the great majority of attributes GE believes that a correct application of the Menzie et al (1996) method would yield lower weights for certain of these attributes For example as discussed below the ERA generally scores the HQs moderatehigh or high for the degree of association between the measurement endpoint and the assessment endpoint based primarily on species-specificity whereas GE believes that the HQs should receive low to moderate scores for these attributes

For most of the HQs the rationale provided in the ERA for assignment of a weight related to degree of association refers only to the species-specificity of the study (pp F-52 G-51 H-501-66 J-51 K-68 shyK-69 Tables F4-7 G4-3 H4-314-4 J4-4 K4-3) Based on the Menzie et al (1996) definition as recognized in the ERA (p 2-68) degree of association refers to the extent to which the measurement endpoint is representative of correlated with or applicable to the assessment endpoint in particular with respect to similarity of effect target organ mechanism of action and level of ecological organization (Menzie et al 1996) Hence while species-specificity is part of the definition of degree of association it is not the sole characteristic of that attribute Other aspects of the biological linkage such as the level of ecological organization should also be considered For example EPA guidance states that the assessment endpoints in Superfund ecological risk assessments should address potential

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adverse effects to local populations and communities of biota (EPA 1999 p 5) While that guidance also notes as the ERA states (p 12-47) that impacts on local populations and communities can be estimated by extrapolating from effects on individuals and groups of individuals using a lines-ofshyevidence approach (EPA 1999 p 3) it should be recognized that lines of evidence such as HQ models which do not address population-level effects should receive lower weight in estimating the degree of association with the population-level assessment endpoints Thus GE recommends that the degree of association of each measurement endpoint be evaluated in accordance with the full definition provided by Menzie et al (1996) including consideration of the level of ecological organization

Moreover in evaluating the species-sensitivity aspect of this attribute the ERA does not adequately account for limited species-specificity in the modeled food intake rates fractions of diets derived from the site or effects metrics The food intake rates are calculated using generic allometric equations and input variables that in some cases are not specific to either the preferred prey of the receptor of interest or the receptor itself The assumption that all receptors (except mink) derive 100 of their food from the Primary Study Area (PSA) also does not account for species-specific foraging ranges Although the use of effects metrics based on species in different taxonomic orders from the receptors of interest is recognized in the weight-of-evidence evaluations it only results in scores being reduced from high to moderatehigh A greater decrease in the score is warranted given the significant uncertainties in interspecies extrapolations Hence the most important variables used in the derivation of HQs generally are not species-specific and the weight-of-evidence scores should be lowered on that basis This problem could be ameliorated for some receptors by basing the HQs where possible on site-specific exposure and effects data for the species in question

Further the ERAs presentation of HQ ranges based on distributions of doses (ie lower bound Monte Carlo and upper bound) suggests that the HQs simulate a full range of exposures to individuals within the local population In actuality the upper bound and Monte Carlo HQs presented in the ERA are based on exposures that represent at most a small number of individuals - namely those that derive 100 of their prey from the PSA (except in the case of mink) and only consume prey that contain the highest concentrations of chemicals of potential concern (COPCs) The ERAs use of point estimates for the parameters of proportion of prey derived from the PSA and concentration of COPCs in prey restricts the applicability of the output of the analyses to a very small number of individuals if any to which these exposure parameters might apply As discussed further in Section 2321 below GE recommends use of distributions for these two parameters so that the output of the HQs might be applicable to a broader range of individuals inhabiting the PSA

Finally Figures 122-1 through 122-4 (pp 12-612-912-1112-12) are confusing in that they suggest that absolute values of HQs are comparable across species and across media of interest (eg sediment soil prey) In order to improve the transparency of the risk characterization GE recommends replacing Figures 122-1 through 122-4 with summary tables of the weight-of-evidence evaluations for all assessment endpoints in order to offer a more balanced approach to comparison of risks

232 Conservatism of HQs The ERA states that HQs are not conservative because no safety factors were used to estimate the effects metrics (except in the case of the bald eagle) and uncertainties regarding the exposure model inputs were explicitly propagated through the probability bounds of the exposure model (p 12-10) While GE recognizes that such safety factors are generally not included in the HQ analyses

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considerable conservatism is contributed to the HQs by both the exposure assumptions and the effects metrics If these sources of conservatism are not corrected through alternate assumptions then the conservatism that they contribute should be explicitly acknowledged in the ERA Some of the general sources of conservatism are discussed below while specific comments on the individual receptors are provided in Section 3

2321 Exposure assumptions For all receptors the ERA states that because food intake rates are poorly characterized in the literature it is necessary to model food intake rates based on allometric equations provided in the Wildlife Exposure Factors Handbook (EPA 1993) (eg pp 7-16 8-17 9-13 10-13 11-13) In fact however the EPA (1993) handbook provides measured species-specific food intake rates for all receptor species evaluated in the ERA except tree swallows river otters American bitterns and small-footed myotis According to EPA (1993) measured species-specific values are preferred over modeling intake rates based on allometric equations (p 3-1) GE recommends the use of the species-specific food intake rates reported in the Wildlife Exposure Factors Handbook (EPA 1993) Where that is not or cannot be done the uncertainty associated with using generic allometric equations and input variables that are not species-specific should be discussed and accounted for in the weight-ofshyevidence evaluations

In addition the use of point estimates to characterize the concentrations of COPCs in food and proportion of food derived from the site appears to be inconsistent with the ERAs own criteria for the use of distributions and point estimates The ERA states that point estimates [are used] for minor variables or variables with low coefficients of variation (p 6-17 H-7) Although coefficients of variation are not presented in the ERA and the sensitivity analyses exclude variables characterized with point estimates concentrations of COPCs in food and proportion of diet derived from the site cannot be described as minor because they directly control the magnitude of estimated dose Use of point estimates for these variables prevents uncertainty from being propagated through the probability bounds of the exposure model (p 12-10) and restricts the applicability of the results to those individuals (if any) that only derive their food from the PSA and that always consume food containing the highest concentrations of COPCs In order to align practices applied in the ERA with the stated methodologies GE recommends representation of these variables with appropriate statistical distributions

2322 Effects metrics Many aspects of the effects metrics also contribute to conservatism and uncertainty in the HQs As described in Section 3 these limitations include (for various receptors) the absence of clear documentation of the practices employed in development of the effects metrics lack of support by the underlying studies or failure to reflect the full body of toxicological literature andor lack of acknowledgment of important sources of uncertainty GE recommends revision of the effects metrics in the ERA as discussed in Section 3

The ERA (eg p 6-20) also states that in all cases effects metrics were consistent with the metrics used in the exposure analysis However the ways in which they are consistent are not defined While the effects metrics and exposure analyses are consistent with respect to units (eg mgkg-day) in many cases they are inconsistent with respect to species exposure duration and dosing regime For example an effect metric based on a domesticated species (ie white leghorn chickens) cannot be

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considered consistent with exposure metrics for wild avian receptors GE recommends revising the above statement so that it specifies the ways in which effects metrics are consistent with exposure metrics GE also recommends that the weight-of-evidence evaluations be modified to account for inconsistencies with respect to species exposure duration and dosing regime

24 Exclusion of Data Quality from Weight-of-Evidence Evaluations Based on Menzie et als (1996) quantitative weight-of-evidence approach data quality is one of the most important attributes in determining the scientific defensibility of a measurement endpoint Nonetheless the ERA does not include data quality as an attribute in the weight-of-evidence evaluations Instead the ERA asserts that all studies used in the ERA (except those conducted by GE contractors) have adequate data quality (p 2-70) However the criteria for determining the adequacy of data quality are not defined the process and outcome of a data quality evaluation are not provided and the underlying studies and data are not provided Consequently it is not possible to verify the validity of the assumption that all data have adequate quality In addition this approach implies that data quality for all measurement endpoints based on EPAs studies are equal In fact data quality varies considerably among the underlying studies For example errors and inconsistencies in the databases and analyses presented in underlying studies were identified in comments that GE has previously submitted to EPA The exclusion of data quality from the weight-of-evidence evaluation prevents EPA from accounting for those differences hi data quality

For these reasons GE urges EPA to modify the ERA so that it (a) specifies all necessary information to allow an independent evaluation of data quality for each measurement endpoint (b) includes the attribute of data quality in the weight-of-evidence evaluations and (c) acknowledges any data quality limitations

25 Discussion of Evidence Regarding Abundant Populations Section 12322 of the ERA lists a number of factors that it asserts indicate that studies showing an abundant population of a given receptor at the site do not demonstrate a lack of adverse effects on that population (pp 12-48 through 12-50) The ERA claims that (a) removal of predators compensates for direct effects of contaminants (b) immigration compensates for direct effects of contaminants (c) populations exposed to COPCs may be more vulnerable to other stressors in the future due to chemical adaptation andor immune system effects The application of these theories to a specific site such as the PSA is speculative and unsupported by the underlying studies None of the studies discussed in the ERA was designed to evaluate these types of effects GE believes that this entire discussion should be deleted from the ERA as speculative and unsupported by the data

26 Extrapolation across Species and Reaches The ERA extrapolates findings for risks posed to individual receptors within the PSA to other species and to areas outside the PSA There are several limitations associated with these practices as discussed below

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261 Risk Comparisons across Species The ERA qualitatively extrapolates predicted risks for each receptor to other species within the same feeding guild based on factors that influence exposure to COPCs (eg diet foraging range body weight) There are a number of problems with this approach First in the absence of data on the other species these extrapolations are not supported by any actual evidence Second these extrapolations of risk do not recognize that risk is a function not only of exposure but also of toxicological sensitivity By making the extrapolations based on factors that relate solely to exposure the ERA implies that all species within a feeding guild are equally sensitive to the toxicological effects of the COPCs However as demonstrated by Brunstrom and Lund (1988) toxicological sensitivity can vary by orders of magnitude across species even for species in the same feeding guild and taxonomic order (eg chickens and turkeys) Hence these analyses should not be referred to as comparisons of risk

The interspecies extrapolations also do not account for field data that either support or refute qualitative conclusions regarding relative risks For example data collected by the Massachusetts Division of Fisheries and Wildlife since 1980 on the productivity of great blue herons throughout Massachusetts show no differences in the numbers of young per nest for herons breeding within or beyond foraging distance of the PSA (MDFW 1979 1980 1981 1982 1983 1984 1985 1986ab 1987 1989 1991 1996) This finding does not support the ERAs qualitative finding that great blue herons face similar to higher risks than American bitterns which are predicted to have high risks (p 12-36)

GE recommends that extrapolations of risk estimates from receptors of interest to other species be omitted from the ERA because they are too uncertain to provide useful information If they are retained GE recommends that the comparisons be accurately characterized as comparisons of potential exposure rather than as comparisons of risk Regardless of how the extrapolations are presented however uncertainties should be explicitly reported including both the inability of the analysis to account for interspecies differences in toxicological sensitivity and cases where available field data contradict the extrapolated findings

262 Extrapolations to Downstream Reaches The field studies surveys and sampling program conducted for the ERA primarily focus on the PSA In an effort to apply the analyses across the entire study area the ERA extrapolates risks downstream of the PSA for seven receptors (benthic invertebrates amphibians warm water fish trout mink otter and bald eagles) For each of these groups the ERA identifies a maximum acceptable threshold concentration (MATC) for total PCBs (tPCBs) Each MATC is then compared to exposure concentrations for individual river and floodplain reaches downstream of Woods Pond to Long Island Sound Areas where exposure concentrations exceed the MATCs are interpreted as indicating potential risks

GE recommends several improvements in this approach (a) revision of the MATCs (b) improved spatial resolution of the overlap between predictions of risk to each receptor and the availability of suitable habitat for those receptors and (c) an explicit discussion of the uncertainties associated with these extrapolations In addition more complete documentation of the methodologies and assumptions employed would enhance the transparency of the analysis

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First several of the MATCs (eg for benthic invertebrates amphibians fish and bald eagles) are not supported by the site-specific studies or the scientific literature Specific concerns related to the basis for these MATCs are discussed below in Sections 311 (benthic invertebrates) 321 amp 322 (amphibians) 332 amp 333 (fish) and 3822 (bald eagles) GE recommends that these MATCs be revised

Second the applicability of the benchmark comparisons for each of the seven receptors should also be considered relative to the available habitat for such receptors in the downstream reaches For example although the MATC for amphibians was developed based on sediment tPCB concentrations in breeding ponds it was applied downstream of Woods Pond to soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data in the downstream reaches (p 12-15) Although such data may be lacking the ERA should make clear that the extrapolation applies only to sediment in potential floodplain ponds downstream of Woods Pond In addition risks to mink otters and bald eagles are evaluated for all reaches of the river with adequate data on exposure concentrations regardless of habitat Restricting the assessment of risks for these receptors to those reaches with suitable habitat would further improve the accuracy of these extrapolations

Third uncertainties in the extrapolations should be discussed and the results should be subjected to a separate weight-of-evidence evaluation

Finally the ERA does not provide enough information regarding the actual methodologies and assumptions used in the analysis of risks downstream of Woods Pond Transparency in this analysis is of paramount importance given the potential influence and use of these extrapolated risk results In particular the ERA should report the actual exposure concentrations used and whether they are spatially weighted averages arithmetic averages 95 upper confidence limits (UCLs) maxima etc In addition EPA should provide at least general information regarding the suitability of the downstream habitat for these receptors or where such information does not exist acknowledge that habitat has not been evaluated and could have a significant effect on any risks downstream of Woods Pond

27 Characterization of GEs Position In several places (pp 2-60 2-61) the ERA characterizes GEs position GE requests that such descriptions of GEs position be removed from the ERA GE will present its position in its comments during the public comment period andor to the Peer Review Panel

28 Non-PCB Constituents The ERA covers the Rest of River which is defined in the Consent Decree (Paragraph 6) as the Housatonic River and its sediments and floodplain areas downstream of the Confluence of the East and West Branches of the Housatonic River including backwaters except for ActualPotential Lawns to the extent that such areas are areas to which Waste Materials that originated at the GE Plant Area have migrated and which are being investigated or remediated pursuant to this Consent Decree (emphasis added) The Revised RCRA Permit contains a similar definition (Definition 19) limiting the Rest of River areas to areas to which releases of hazardous wastes andor hazardous constituents are migrating or have migrated from the GE Facility

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The ERA recognizes that the Rest of River includes areas of the Housatonic River and its sediments and floodplain (except ActualPotential Lawns) in which contaminants migrating from the GE facility are located (p 1-2) However it includes as COPCs a number of non-PCB constituents that are or may not be related to releases from the GE facility These include for various media numerous polycyclic aromatic hydrocarbons (PAHs) and other semi-volatile organic compounds (SVOCs) dioxins and furans several metals and (for fish) certain pesticides (Tables 24-2 through 24-5) There are multiple potential sources of these constituents in the Rest of River area not just releases from the GE facility

To avoid any confusion the ERA should make clear in its discussions of the COPCs (Sections 231 and 243) that while several COPCs other than PCBs have been selected for the ERA there are multiple potential sources of these constituents and hence there is no evidence demonstrating that the occurrence of these COPCs in the Rest of River area is necessarily derived from releases attributable to GE

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3 Specific Comments

31 Benthic Invertebrates In its assessment of benthic invertebrates the ERA derives toxicity thresholds (MATCs) of 3 mgkg tPCB in both tissue (based on the literature) and sediments (based on the results of toxicity and benthic community studies) GE believes that these thresholds should be reevaluated As discussed in this section GE urges EPA to make the following changes to the ERAs assessment of benthic invertebrates (a) use a different data set to calculate sediment-based toxicity thresholds (b) take adequate account of sediment grain size in interpreting the benthic community and toxicity test results (c) reduce the emphasis on Sediment Quality Values and the Toxicity Identification Evaluation (TIE) results (d) recognize a number of additional specified uncertainties and (e) clarify or provide additional information on certain issues

311 Concentration-Response Analysis to Derive Sediment Toxicity Thresholds The ERA concludes that the toxicity studies showed ecologically significant effects at sediment tPCB concentrations of 3 mgkg or higher (pp 3-71 D-98) the proposed MATC for sediment This proposed toxicity threshold is apparently based on LCso and ICso values from laboratory studies that were calculated based on the median values of multiple grab samples (p D-10) (some of which were collected independently of the laboratory bioassays) rather than based on measured concentrations of PCBs in sediments actually used in these bioassays The use of these unrelated data as a basis for establishing exposure levels in laboratory bioassays is of concern given that PCB concentrations in sediments of the Housatonic River can vary by orders of magnitude over very small spatial and temporal scales (pp D-26 to D-28) The rationale given for this method is that combining data from sampling events that are approximately (but not exactly) synoptic with the effects data more accurately portrays the COC concentrations at each station (p D-27) This approach may provide an indication of PCB concentrations in the vicinity of a station over time but it does not provide a better measure of PCB concentrations in the specific composites used in the bioassays than would a direct measure of PCBs in the sediments used in the bioassays For some stations concentrations measured directly from the composites are in fact substantially different than those derived from other collection efforts (Figures D3-1 through D3-5 Stations 7 and 8A) resulting in variability which likely substantially affects the exposure-response analyses and resulting LCsos and ICsoS Because of this variability it is important that effects levels for bioassay tests be calculated from the data that represent the concentrations to which these organisms were actually exposed

GE recommends that the ERA be revised to calculate the No Observed Adverse Effect Levels (NOAELs) Lowest Observed Adverse Effect Levels (LOAELs) and LCsoICso values for the laboratory bioassays (Tables D4-2 and D4-3) based on the synoptic values derived directly from the composite samples for the laboratory bioassays because these values best represent the exposures to the test organisms The LCao and IC20 values should also be revised in a similar manner as should the linear regression models (Table D4-4 Figure D4-5)

312 Effects of Grain Size on Study Interpretation Grain size is a significant variable that can impact both benthic community structure and the endpoints evaluated in the laboratory toxicity studies However in several instances the ERA does not adequately consider the effects of grain size in interpreting the study results

The ERA states that the benthic community data indicated that five of the six stations with median tPCB concentrations above 5 mgkg had significant benthic community alteration (p D-98) Those same five stations had coarse-grained sediments (see Figures D4-6 and D4-7) The one fine-grained station with median tPCB concentrations greater than 5 mgkg (Station 8) had higher species richness and abundance than the coarse-grained stations and was not significantly different from the reference stations (see Figures D4-6 D4-7 and D4-15) Benthic invertebrates tend to be the least diverse and the least abundant in sand likely due to its instability (Ward 1992 Minshall 1984 Allan 1995) Thus even in the absence of PCBs the diversity and abundance of invertebrates would be expected to be lower at the coarse-grained stations In these circumstances it is at least equally likely that grain size rather than PCB concentration explains the spatial variations in benthic community structure As a result the statements throughout the ERA regarding the high level of confidence in the conclusion that benthic invertebrates in the Housatonic River experience unacceptable risks due to tPCBs (eg p 12-55) are not be supported Those statements should be revised to recognize the confounding impacts and uncertainty associated with grain size effects and to note that as a result the benthic community data do not provide conclusive evidence of tPCB effects on changes in community structure

Similar concerns apply to the bioassay test The reference stations used in the bioassay test (Al and A3) are coarse-grained (Figure D2-2) whereas the treatment stations showing the highest levels of response (Stations 7 8 and 8A) are fine-grained Statistical analyses and the weight of evidence evaluation are based on comparisons made between Housatonic River sediment stations and references regardless of grain size (Table D3-4 and Figure D4-15) The uncertainty associated with comparing the toxicity of fine-grained stations to coarse-grained reference treatments should be acknowledged

313 Use of Sediment Quality Values and Toxicity Identification Evaluation in the Weight-of-Evidence

The ERA also relies on published Sediment Quality Values (SQVs) to support a sediment toxicity threshold value of 3 to 5 mgkg (pp 3-71 D-98) SQVs are generic in nature and therefore are primarily appropriate in screening-level ERAs when no site-specific data are available (see eg Long et al 1995) Given the availability of substantial site-specific data the generic SQVs should not be used at all or at a minimum given very low weight and the references to them should be removed from the conclusions

The ERA also gives moderate weight to the results of the Toxicity Identification Evaluation (TIE) (Table D4-5) The ERA concludes from this Phase I TIE that PCBs may be the main causal agent in the toxicity studies (p D-78) However the TIE was not a definitive study and was not designed to provide an independent evaluation of effects and the results of the TIE are inconclusive showing only that non-polar organic chemicals were likely responsible for the observed toxicity As a result while the results of the TIE provide some evidence as to the degree to which observed effects can be linked to PCBs rather than other COPCs the TIE study should be removed as a separate line of evidence

314 Need to Acknowledge Additional Uncertainties There are a number of uncertainties associated with the benthic invertebrate studies Some of these are acknowledged in the text (pp D-95 through D-98) but other critical uncertainties are not The text should be revised to acknowledge the following uncertainties

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Lack of concordance between benthic community and sediment toxicity study results At the four stations for which there are both sediment toxicity test data and benthic community data those results are contradictory The sediment toxicity tests show a toxic response for most endpoints (especially at Stations 7 and 8) whereas the benthic community analyses do not (see Figure D4-15) GE recommends that the ERA be revised to discuss this point in the uncertainty section and also to carry this through to the conclusions in terms of the ability to extrapolate the potential for adverse effects to downstream locations

Inconsistent patterns oftPCB concentrations in sediment and tissues The ERA likewise does not discuss the fact that the median tPCB concentrations in sediments and those in tissue are not consistent (eg elevated tPCB concentrations in sediments were not co-located with those in tissue) (compare Figure 33-3 on p 3-18 with Figure 33-6 on p 3-22) These inconsistencies raise questions regarding the reliability of using median sediment concentrations as a measure of exposure for benthic invertebrates They also limit the usefulness of the biota sediment accumulation factors (BSAFs) which range from 08 to 61 (p D-32) in predicting tissue levels from sediment concentrations These inconsistencies should be acknowledged in the discussion of tissue chemistry (Section 335 pp 3-21 and 3-23) and the implications relative to estimating exposure should be addressed in the uncertainty section

Calculation of LC$o and ICso values The toxicity test endpoints presented in Tables D4-1 through D4-3 based on statistical analyses have a number of significant uncertainties Specifically uncertainties are associated with the results in which (a) the chi-square value exceeds the critical value in the derivation of LCjos and LC2os (20 out of 54 endpoints) (b) visual observations rather than the probit analyses were used because the model did not converge (2 out of 54 endpoints) and (c) there was an interrupted dose-response (9 of 54 endpoints) These difficulties with the statistical analyses are indicative of inconsistencies in the dose-response relationships that result in uncertainty surrounding the threshold values These uncertainties should be addressed (Tables D4-1 - D4-3) In addition no explanation is provided for why the highest dose (772 mgkg) for H azteca 48-h survival is excluded from the effects threshold analysis (Table D4-1) Additional information should be included regarding its exclusion or the analyses should be redone using the results of this treatment

Use of single samples to characterize sediment in used in bioassays A discussion of the uncertainty associated with determining exposure values of sediment composites used in toxicity testing based on a single chemistry sample should be provided (p D-17) Alternatively if multiple samples were used to evaluate potential heterogeneity in these composites to confirm that sediment was completely mixed then those data should be provided

315 Need for Additional Clarification and Information This section describes a number of issues for which the next draft of the ERA should provide clarification or additional data or analyses

Tissue effects thresholds from the literature The ERA states that the literature review was focused on Aroclor 1260 and 1254 (p 3-14) It should be revised to state that no effects thresholds were found based on studies with Aroclor 1260 and that only studies of tPCBs Aroclor 1254 and Clophen A50 were used to derive these thresholds The figures summarizing the literature effects thresholds should also be revised to indicate which study is associated with the effects reported (eg in Figure 44-13)

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and to indicate that studies with Clophen A50 are included in the summary In addition congenershyspecific studies should be removed from the literature review (Table D3-5 and Attachment DI) as they are not appropriate surrogates for tPCB toxicity

Multi-dimensional scaling analysis The results of the multi-dimensional scaling (MDS) statistical analyses used to develop Figures D3-15 through D3-17 should be presented This will provide important information regarding the relative contribution of different factors in this multivariate analysis

Derivation of MATCs The ERA does not explain explicitly how the sediment MATC of 3 mgkg tPCB (p 3-72) used to assess the extent of risks downstream from the PSA was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should specifically document the derivation of the MATC value used

32 Amphibians In the assessment of amphibians the ERA derives toxicity thresholds (MATCs) of 1 mgkg in both tissue (based on the literature) and sediments (based on the results of EPAs wood frog study) As discussed below GE believes that neither of these thresholds is supported by the underlying studies and that they should be higher Moreover in evaluating the results of the wood frog study the ERA does not consider certain endpoints (metamorphosis and mortality) that have clear ecological relevance these endpoints should be included in the evaluation In addition as further discussed in these comments we urge EPA to (a) give lower weight to the results of the leopard frog study and explicitly recognize its use of external reference frogs (b) recognize additional specified uncertainties in the amphibian assessment (c) clarify or present additional data or analyses on certain issues (d) modify the extrapolation to reaches downstream of Woods Pond and (e) correct an error in the text1

321 Lack of Literature Support for a Toxicity Threshold of 1 mgkg tPCBs in Tissue The ERA specifies a toxicity threshold of 1 mgkg in tissue based on a review of the literature (pp 4shy75 E-96) The studies and results used in this review are summarized in Figures 44-13 and E3-37 However the two tPCB LOAELs (called LOELs in these figures) below 1 mgkg shown in these figures are not supported by the underlying study (Gutleb et al 2000) One of these effects levels for time to metamorphosis for the African clawed frog is based on exposure to PCB 126 although tissue chemistry was analyzed as tPCBs Comparing tPCB concentrations to effects levels from a study in which larvae were exposed to PCB 126 would substantially overstate tPCB toxicity and hence this effect level should not be used to evaluate potential tPCB effects The second LOAEL for the European common frog is 024 mgkg tPCBs (wet weight2) in tissue (based on exposure to Clophen A50) However at that concentration there was no adverse effect body weight in the exposed frogs was higher not lower than in the control frogs In fact there was no significant effect on body weight at the highest tissue concentration used in this study (112 mgkg tPCBs wet weight) Hence the latter

1 As noted in Section 1 EPA has also agreed to include the frog study sponsored by GE (Resetarits 2002) in the next draft of the ERA In addition GE has recently completed a study of leopard frog egg masses in the PSA and is providing a report on that study to EPA (ARCADIS 2003) That study should likewise be included in the next draft of the ERA

2 As converted from lipid weight in Attachment E2

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value should be reported as an unbounded NOAEL for that endpoint and the value reported as a LOAEL (024 mgkg) should be removed from these figures

Additional concerns associated with the summary of the literature effects are related to the interpretation of the frequency of occurrence of adverse effects (p 4-56 and E-81) First three LOAELs are cited for mortality based on a single experiment (Savage et al 2002) (Figure 4431 p 4shy57 and E3-37 p 60) By definition a LOAEL is the lowest concentration in an experiment for which there is a statistically significant difference relative to the control therefore only the LOAEL at approximately 6 mgkg from this study should be included in this figure When the erroneous LOAEL (Gutleb et al 2000) and the redundant LOAELs (Savage et al 2002) are removed the frequency of adverse effect analysis indicates that 4 out of 12 endpoints (for tPCBs) or 33 demonstrate adverse effects at concentrations greater than 1 mgkg and that in fact no adverse effects are observed below 6 mgkg

In addition the meaning of this frequency of adverse effects is not clear because there are substantive differences between the nature of effects observed For example the endpoints of reduced activity or swimming speed may or may not have the same severity of impact to an individual as increased mortality This distinction is lost in a simple evaluation of frequency of effects between different endpoints in various literature studies

Based on the above discussion the statement that [tjhere were six instances of adverse effects occurring between 1 and 10 mgkg (pp 4-56 and E-81) should be revised For tPCBs there are only three LOAELs (ie incidence of adverse effects) between 1 and 10 mgkg and all them are at or above 6 mgkg The text should be revised accordingly If the interpretation of these studies based on the frequency of adverse effects is retained that text should also be revised and uncertainties associated with direct comparisons of the different kinds of effects included in this analysis should be acknowledged

322 Lack of Support for a Sediment Toxicity Threshold of 1 mgkg Based on Wood Frog Study

The sediment toxicity threshold of 1 mgkg is apparently based primarily on an analysis of the results of EPAs wood frog study However the description of the results of that study states that [e]cologically significant adverse effects in late stage juvenile wood frogs occurred in the sediment tPCB concentration range of 10 to 60 mgkg although responses of lesser magnitude yet statistically significant were observed at 5 mgkg tPCB and lower (p 4-60) The latter statement (which may be the basis for the threshold) is apparently derived from the wood frog NOAELs and LOAELs presented in Table E4-2 However there are several problems or inconsistencies in the derivation of site-specific NOAELs and LOAELs presented in Table E4-2

bull In several instances the NOAELs and LOAELs do not coincide with sediment concentrations that are associated with the effects data For example the spatially weighted mean tPCB value of 136 mgkg is presented as either a NOAEL or LOAEL for all four endpoints in Table E4-2 However it appears that this value is associated with a vernal pool (46-VP-4 Table E2-8) that has no effects data associated with it (see Tables E3-5- E3-6 and E 310 - E3-11)

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bull It appears that the reference WML-1 has been excluded from the calculation of NOAELs and LOAELs for Phase III metamorphs because of zero response at this concentration(Table E4-2) This exclusion is not warranted While the text refers to the tissue tPCB concentration for reference location WML-1 in the Phase III of the wood frog study as anomalous (eg p 4-52) no problems with data quality are reported that would indicate that the organism did not in fact have a tissue burden of 44 mgkg tPCBs As a result responses associated with this exposure level should be considered to represent part of the range of effects and all analyses of exposure and effect should include this reference site Statistical comparisons with a zero value are commonly made using a value marginally greater than zero (eg 000001)

bull Concentration-response relationships for each endpoint were evaluated using both (1) the most synoptic chemistry value paired with each toxicity endpoint (also referred to as vernal pool sediment) and (2) a combined data set used to generate a spatially weighted surface average (pp 4shy16 mdash 4-17) Given the variability in sediment concentrations the samples used in the laboratory toxicity study should not be assumed to be equivalent to the surface weighted average The synoptic (ie vernal pool) data reflect the actual tPCB concentrations measured in sediments used in the laboratory exposures and should thus should be used for analyses of the Phase I wood frog study which was conducted in the laboratory The surface weighted averages should be used for the analysis of Phase II and Phase III studies in which larvae and metamorphs were exposed in the field as they encompass the range of concentrations to which the growing larvae and metamorphs might have been exposed to The NOAELs LOAELs and point estimates for effects concentrations (eg LC50 and LC20) (Table E4-2) should be revised accordingly

bull Table E4-2 states that the reference site had no malformed specimens (Phase II metamorphs percent malformed) In fact Table E3-11 indicates that reference site WML-3 had 29 malformations

Moreover the toxicity threshold for wood frogs was derived based only on endpoints that showed effects The ERA states that if no discern[i]ble differences in effect levels across treatments were observed (ie inadequate range in response variable) the effects endpoint was not considered in the detailed statistical evaluation (p E-90) As a result as discussed in the next section the lack of PCB-related effects for key endpoints (ie mortality and metamorphosis) were not considered in the derivation of the effects threshold Consideration of the results for those omitted endpoints shows further that the sediment MATC of 1 mgkg is too low

We also note that although Appendix E presents tissue-based HQs for leopard frogs and wood frogs (pp E-96 - E-98) Section 12 of the ERA presents only sediment-based HQs (Figures 122-1 and p 12shy7) Tissue concentrations provide a more direct measure of exposure than do sediment concentrations and hence the tissue-based rather than sediment-based HQs should be used in Section 12

323 Need to Consider Additional Relevant Endpoints in Wood Frog Study As noted above in evaluating the results of the wood frog study two endpoints with clear ecological relevance ~ metamorphosis and mortality -- were screened out of the formal concentration-response modeling due to a lack of discern[i]ble differences in effect levels across treatments (p E-90) However these two endpoints integrate other effects (ie the most serious effect of malformations would be reduced metamorphosis and increased mortality) and should be carried through the

concentration-response evaluation If no concentration-response curve can be derived because there were no effects then the highest dose should be treated as a NOAEL for these endpoints the LC50

should be expressed as gt highest dose and both mortality and metamorphosis should be considered subsequently as part of the lines-of-evidence evaluation

324 Evaluation of the Leopard Frog Study EPAs leopard frog study receives the same overall weight (moderatehigh) as its wood frog study in the weight-of evidence-evaluation (Table 45-4 p 4-69) Considering the significant problems with the leopard frog study as detailed in GEs comments on this study (BBL Sciences et al 2003a) it should be accorded a low weight

Moreover the text does not consistently acknowledge that reference frogs for the leopard frog study were obtained from a biological supply company For readers unfamiliar with the underlying study this could lead to misinterpretations of the results presented The text should be modified to clearly represent this aspect of the leopard frog study as well as additional qualifications as follows

bull The first time the study design of the leopard frog study is presented it should be clearly stated that no frogs or eggslarvae were found in the reference areas (p 4-13)

bull The text that describes comparisons between both the toxicity studies and the community evaluations and appropriately matched field references (p 4-27) should be revised to indicate that for the leopard frog study the field reference was limited to sediment not frogs collected from a reference pond

bull Although the text states that reference ponds were surveyed for eggs and larvae it does not indicate that in addition to no eggs or larvae being found at four of nine contaminated sites none were found at the reference sites (p 4-35)

bull Similarly the summary of female leopard frog reproductive fitness identifies all of the Housatonic River sites that were not gravid (did not have eggs mature enough for successful fertilization) (p 4shy30) It should also indicate that R2 (external reference) did not have any successful fertilization

325 Need to Acknowledge Additional Uncertainties While the ERA acknowledges some uncertainties associated with the amphibian studies (pp 4-70 4shy73 E-108-110) other critical uncertainties are not acknowledged For example there are uncertainties associated with the concentration-response analysis (eg ECsos ECaos) based on the poor fit of the data in the probit analysis Contrary to the statement that most endpoints followed a fairly smooth concentration-response (text box p 4-60) Table E4-2 indicates that only one of 11 of the ECsos presented (ie Phase III metamorph percent malformed based on comparisons with the lowest vernal pool sediment tPCB concentration) appears to be appropriately described by the probit analysis The other ECsos were described as (a) outside data range confidence limits increase (111) (b) probit model had poor fit to data confidence limits increase (111) (c) calculated with linear interpolation no confidence limits can be calculated (311) and (d) based on visual inspection of data (511) These uncertainties should be recognized

326 Need for Additional Information There are a number of issues on which we urge EPA to provide additional information in the next draft of the ERA

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Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

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Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

1 Introduction The General Electric Company (GE) submits these comments to the US Environmental Protection Agency (EPA) on EPAs April 2003 draft of its Ecological Risk Assessment for General Electric (GE)Housatonic River Site Rest of River (hereinafter ERA) These comments were prepared on GEs behalf by BBL Sciences Inc ARCADIS GampM Inc LWB Environmental and Branton Environmental Consulting

GE has many concerns and disagreements with the approaches and inputs used the evaluations provided and the conclusions reached in the ERA However in light of discussions with EPA these comments do not discuss all of GEs concerns and disagreements with the ERA In several prior submissions to EPA GE andor its consultants have presented both general and specific comments on EPAs ERA work plans and on the plans and reports on many of the underlying studies that were performed by EPA contractors and included in the ERA The present comments do not repeat all of those points again Rather the focus of these comments is to provide input to EPA that will improve the ERA prior to the next draft In particular GE has attempted to focus these comments on major issues involving errors or internal inconsistencies in the ERA evaluations or conclusions that we believe are not supported by the evidence and uncertainties that we believe should be more explicitly recognized in the ERA However GE preserves its positions on all issues and points on which it has previously submitted comments to EPA and reserves the right to raise these or any other issues or points in its comments on the ERA during the public comment period andor in its presentations to the Peer Review Panel for the ERA The fact that GE has not raised a particular issue in these comments should not be regarded as agreement to the way in which the ERA has addressed that issue

In addition GE has provided EPA with reports on a number of ecological studies conducted by GE contractors over the past few years which we believe are directly relevant to the ERA Although the current draft ERA mentions these studies it does not discuss them or include them in any of the evaluations or weight-of-evidence analyses in the ERA The current draft notes that these GE studies will be discussed and evaluated in the next draft of the ERA However given the absence of such a discussion or evaluation in the current draft GE is unable to offer comments on EPAs assessment of these studies or how EPAs consideration of them may or should change EPAs overall evaluation or conclusions regarding the receptors involved in these studies In its comments during the public comment period andor in its presentations to the Peer Review Panel GE will provide comments on EPAs discussion evaluation and weighting of these studies in the next draft of the ERA as well as on the implications of these studies for the assessment of potential impacts to local populations and communities of these receptors

These comments are organized as follows Section 2 provides a number of general comments that apply to multiple assessment endpoints or the overall approach used to evaluate risk in this ERA including its overall approach to evaluating the available lines of evidence and implementing the weight-of-evidence analyses and its procedures for extrapolating risks to species and areas that were not studied Section 3 then provides more specific comments on each of the receptor groups considered in the ERA as well as examples of some of the issues raised in Section 2

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2 General Comments A number of general issues apply to multiple assessment endpoints or the overall approach used to evaluate risk in this ERA The general issues discussed below include (a) omission of underlying studies and data (b) exclusion of lines of evidence prior to the weight-of-evidence evaluations (c) overemphasis on hazard quotients (HQs) based on modeled exposures and effects (d) exclusion of data quality from the weight-of-evidence evaluations (e) discussion of evidence regarding abundant populations (f) extrapolations across species and reaches (g) characterization of GEs position and (h) treatment of constituents other than polychlorinated biphenyls (PCBs)

21 Underlying Studies and Data Omitted Neither the reports on the studies that form the basis for many of the measurement endpoints nor the underlying database are provided within or in attachments to the ERA In the absence of the underlying studies and data it is not possible to independently validate calculations statistics or interpretation of those studies EPAs (2002b) Guidelines for Ensuring the Quality Objectivity Utility and Integrity of Information Disseminated by the Environmental Protection Agency emphasize the importance of the reproducibility of such information by qualified third parties (EPA 2002b pp 20-21) GE believes that to ensure the transparency of the ERA the underlying study reports and database should be included as appendices to the ERA (in either paper or electronic form) Through that approach if a commenter or member of the Peer Review Panel wishes to evaluate the underlying basis for a statement or conclusion in the ERA the information necessary to do so will be available

22 Exclusion of Lines of Evidence Prior to the Weight-of-Evidence Evaluations The ERA screens out select lines of evidence (mainly some field studies conducted by EPA contractors) prior to the weight-of-evidence evaluations instead of including all available lines of evidence in the weight-of-evidence evaluations In GEs view this practice is not consistent with the purposes of performing a weight-of-evidence evaluation mdash ie to consider the scientific defensibility of all available lines of evidence to reconcile those lines of evidence and to conclude whether significant risk of harm is posed to the environment (Menzie et al 1996) Moreover this approach does not appear to be systematically applied across receptors For example EPAs fish biomass study is excluded from the weight-of-evidence evaluation on the ground that meaningful statistical assessment of PCS or TEQ relationship to fish community parameters was not feasible (p 5-43) However the qualitative observations of amphibian community structure and the minkotter surveys are (appropriately) included in the weight-of-evidence evaluation despite the fact that like the biomass study statistical evaluations of exposure-response are not possible Additionally the avian surveys are not included in the weight-of-evidence evaluations even though they are initially listed as measurement endpoints for evaluating threatened and endangered species (p 11-6)

GE urges EPA to include all available lines of evidence in the weight-of-evidence evaluations These would include all field-based studies that EPA conducted as well as all studies conducted by GE contractors

In addition for some studies (eg EPAs wood frog study and its Phase II fish toxicity study) the draft ERA includes only a subset of the available endpoints in the weight-of-evidence evaluations as

discussed further in Section 3 In such cases GE urges EPA to evaluate all available and relevant individual lines of evidence from these particular studies

23 Overemphasis on Hazard Quotients The ERA derives Hazard Quotients (HQs) from modeled exposure and effects for the majority of receptors and assesses them as lines of evidence typically according them moderatehigh or high weight In addition the Risk Summary (Section 12) presents the Monte Carlo-based HQs for all receptors to facilitate comparison of risks among aquatic life and wildlife receptors and to give a broad overview of the findings of the risk assessment (p 12-3) Indeed in that section the consideration of other lines of evidence is restricted to a very brief risk characterization that acknowledges that some of the receptors were evaluated based on multiple lines of evidence but does not put the HQs which represent only one of these lines of evidence into this context (pp 12-54 through 12-55) As a result the HQs dominate the presentation of risk in that section

These practices place too much weight and emphasis on the HQs relative to other lines of evidence and tends to obscure the high degree of conservatism and uncertainty associated with the HQs GEs concerns regarding the ERAs interpretation of the HQs and the conservatism and uncertainties present in them are discussed below

231 Interpretation of HQs GE has several concerns with the ERAs interpretation of HQs First in applying the weight-ofshyevidence approach to the HQs the ERA generally does not consider all aspects of the degree of association attribute as defined by Menzie et al (1996) and does not adequately account for limitations in the species-specificity of key input variables Second the HQs are presented in a manner that erroneously suggests that they reflect a full range of individual exposures within the local population Finally the presentation of HQs is confusing in some respects These concerns are further detailed in this section

In applying the weight-of-evidence approach to the HQs the ERA generally assigns moderatehigh or high weight to the great majority of attributes GE believes that a correct application of the Menzie et al (1996) method would yield lower weights for certain of these attributes For example as discussed below the ERA generally scores the HQs moderatehigh or high for the degree of association between the measurement endpoint and the assessment endpoint based primarily on species-specificity whereas GE believes that the HQs should receive low to moderate scores for these attributes

For most of the HQs the rationale provided in the ERA for assignment of a weight related to degree of association refers only to the species-specificity of the study (pp F-52 G-51 H-501-66 J-51 K-68 shyK-69 Tables F4-7 G4-3 H4-314-4 J4-4 K4-3) Based on the Menzie et al (1996) definition as recognized in the ERA (p 2-68) degree of association refers to the extent to which the measurement endpoint is representative of correlated with or applicable to the assessment endpoint in particular with respect to similarity of effect target organ mechanism of action and level of ecological organization (Menzie et al 1996) Hence while species-specificity is part of the definition of degree of association it is not the sole characteristic of that attribute Other aspects of the biological linkage such as the level of ecological organization should also be considered For example EPA guidance states that the assessment endpoints in Superfund ecological risk assessments should address potential

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adverse effects to local populations and communities of biota (EPA 1999 p 5) While that guidance also notes as the ERA states (p 12-47) that impacts on local populations and communities can be estimated by extrapolating from effects on individuals and groups of individuals using a lines-ofshyevidence approach (EPA 1999 p 3) it should be recognized that lines of evidence such as HQ models which do not address population-level effects should receive lower weight in estimating the degree of association with the population-level assessment endpoints Thus GE recommends that the degree of association of each measurement endpoint be evaluated in accordance with the full definition provided by Menzie et al (1996) including consideration of the level of ecological organization

Moreover in evaluating the species-sensitivity aspect of this attribute the ERA does not adequately account for limited species-specificity in the modeled food intake rates fractions of diets derived from the site or effects metrics The food intake rates are calculated using generic allometric equations and input variables that in some cases are not specific to either the preferred prey of the receptor of interest or the receptor itself The assumption that all receptors (except mink) derive 100 of their food from the Primary Study Area (PSA) also does not account for species-specific foraging ranges Although the use of effects metrics based on species in different taxonomic orders from the receptors of interest is recognized in the weight-of-evidence evaluations it only results in scores being reduced from high to moderatehigh A greater decrease in the score is warranted given the significant uncertainties in interspecies extrapolations Hence the most important variables used in the derivation of HQs generally are not species-specific and the weight-of-evidence scores should be lowered on that basis This problem could be ameliorated for some receptors by basing the HQs where possible on site-specific exposure and effects data for the species in question

Further the ERAs presentation of HQ ranges based on distributions of doses (ie lower bound Monte Carlo and upper bound) suggests that the HQs simulate a full range of exposures to individuals within the local population In actuality the upper bound and Monte Carlo HQs presented in the ERA are based on exposures that represent at most a small number of individuals - namely those that derive 100 of their prey from the PSA (except in the case of mink) and only consume prey that contain the highest concentrations of chemicals of potential concern (COPCs) The ERAs use of point estimates for the parameters of proportion of prey derived from the PSA and concentration of COPCs in prey restricts the applicability of the output of the analyses to a very small number of individuals if any to which these exposure parameters might apply As discussed further in Section 2321 below GE recommends use of distributions for these two parameters so that the output of the HQs might be applicable to a broader range of individuals inhabiting the PSA

Finally Figures 122-1 through 122-4 (pp 12-612-912-1112-12) are confusing in that they suggest that absolute values of HQs are comparable across species and across media of interest (eg sediment soil prey) In order to improve the transparency of the risk characterization GE recommends replacing Figures 122-1 through 122-4 with summary tables of the weight-of-evidence evaluations for all assessment endpoints in order to offer a more balanced approach to comparison of risks

232 Conservatism of HQs The ERA states that HQs are not conservative because no safety factors were used to estimate the effects metrics (except in the case of the bald eagle) and uncertainties regarding the exposure model inputs were explicitly propagated through the probability bounds of the exposure model (p 12-10) While GE recognizes that such safety factors are generally not included in the HQ analyses

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considerable conservatism is contributed to the HQs by both the exposure assumptions and the effects metrics If these sources of conservatism are not corrected through alternate assumptions then the conservatism that they contribute should be explicitly acknowledged in the ERA Some of the general sources of conservatism are discussed below while specific comments on the individual receptors are provided in Section 3

2321 Exposure assumptions For all receptors the ERA states that because food intake rates are poorly characterized in the literature it is necessary to model food intake rates based on allometric equations provided in the Wildlife Exposure Factors Handbook (EPA 1993) (eg pp 7-16 8-17 9-13 10-13 11-13) In fact however the EPA (1993) handbook provides measured species-specific food intake rates for all receptor species evaluated in the ERA except tree swallows river otters American bitterns and small-footed myotis According to EPA (1993) measured species-specific values are preferred over modeling intake rates based on allometric equations (p 3-1) GE recommends the use of the species-specific food intake rates reported in the Wildlife Exposure Factors Handbook (EPA 1993) Where that is not or cannot be done the uncertainty associated with using generic allometric equations and input variables that are not species-specific should be discussed and accounted for in the weight-ofshyevidence evaluations

In addition the use of point estimates to characterize the concentrations of COPCs in food and proportion of food derived from the site appears to be inconsistent with the ERAs own criteria for the use of distributions and point estimates The ERA states that point estimates [are used] for minor variables or variables with low coefficients of variation (p 6-17 H-7) Although coefficients of variation are not presented in the ERA and the sensitivity analyses exclude variables characterized with point estimates concentrations of COPCs in food and proportion of diet derived from the site cannot be described as minor because they directly control the magnitude of estimated dose Use of point estimates for these variables prevents uncertainty from being propagated through the probability bounds of the exposure model (p 12-10) and restricts the applicability of the results to those individuals (if any) that only derive their food from the PSA and that always consume food containing the highest concentrations of COPCs In order to align practices applied in the ERA with the stated methodologies GE recommends representation of these variables with appropriate statistical distributions

2322 Effects metrics Many aspects of the effects metrics also contribute to conservatism and uncertainty in the HQs As described in Section 3 these limitations include (for various receptors) the absence of clear documentation of the practices employed in development of the effects metrics lack of support by the underlying studies or failure to reflect the full body of toxicological literature andor lack of acknowledgment of important sources of uncertainty GE recommends revision of the effects metrics in the ERA as discussed in Section 3

The ERA (eg p 6-20) also states that in all cases effects metrics were consistent with the metrics used in the exposure analysis However the ways in which they are consistent are not defined While the effects metrics and exposure analyses are consistent with respect to units (eg mgkg-day) in many cases they are inconsistent with respect to species exposure duration and dosing regime For example an effect metric based on a domesticated species (ie white leghorn chickens) cannot be

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considered consistent with exposure metrics for wild avian receptors GE recommends revising the above statement so that it specifies the ways in which effects metrics are consistent with exposure metrics GE also recommends that the weight-of-evidence evaluations be modified to account for inconsistencies with respect to species exposure duration and dosing regime

24 Exclusion of Data Quality from Weight-of-Evidence Evaluations Based on Menzie et als (1996) quantitative weight-of-evidence approach data quality is one of the most important attributes in determining the scientific defensibility of a measurement endpoint Nonetheless the ERA does not include data quality as an attribute in the weight-of-evidence evaluations Instead the ERA asserts that all studies used in the ERA (except those conducted by GE contractors) have adequate data quality (p 2-70) However the criteria for determining the adequacy of data quality are not defined the process and outcome of a data quality evaluation are not provided and the underlying studies and data are not provided Consequently it is not possible to verify the validity of the assumption that all data have adequate quality In addition this approach implies that data quality for all measurement endpoints based on EPAs studies are equal In fact data quality varies considerably among the underlying studies For example errors and inconsistencies in the databases and analyses presented in underlying studies were identified in comments that GE has previously submitted to EPA The exclusion of data quality from the weight-of-evidence evaluation prevents EPA from accounting for those differences hi data quality

For these reasons GE urges EPA to modify the ERA so that it (a) specifies all necessary information to allow an independent evaluation of data quality for each measurement endpoint (b) includes the attribute of data quality in the weight-of-evidence evaluations and (c) acknowledges any data quality limitations

25 Discussion of Evidence Regarding Abundant Populations Section 12322 of the ERA lists a number of factors that it asserts indicate that studies showing an abundant population of a given receptor at the site do not demonstrate a lack of adverse effects on that population (pp 12-48 through 12-50) The ERA claims that (a) removal of predators compensates for direct effects of contaminants (b) immigration compensates for direct effects of contaminants (c) populations exposed to COPCs may be more vulnerable to other stressors in the future due to chemical adaptation andor immune system effects The application of these theories to a specific site such as the PSA is speculative and unsupported by the underlying studies None of the studies discussed in the ERA was designed to evaluate these types of effects GE believes that this entire discussion should be deleted from the ERA as speculative and unsupported by the data

26 Extrapolation across Species and Reaches The ERA extrapolates findings for risks posed to individual receptors within the PSA to other species and to areas outside the PSA There are several limitations associated with these practices as discussed below

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261 Risk Comparisons across Species The ERA qualitatively extrapolates predicted risks for each receptor to other species within the same feeding guild based on factors that influence exposure to COPCs (eg diet foraging range body weight) There are a number of problems with this approach First in the absence of data on the other species these extrapolations are not supported by any actual evidence Second these extrapolations of risk do not recognize that risk is a function not only of exposure but also of toxicological sensitivity By making the extrapolations based on factors that relate solely to exposure the ERA implies that all species within a feeding guild are equally sensitive to the toxicological effects of the COPCs However as demonstrated by Brunstrom and Lund (1988) toxicological sensitivity can vary by orders of magnitude across species even for species in the same feeding guild and taxonomic order (eg chickens and turkeys) Hence these analyses should not be referred to as comparisons of risk

The interspecies extrapolations also do not account for field data that either support or refute qualitative conclusions regarding relative risks For example data collected by the Massachusetts Division of Fisheries and Wildlife since 1980 on the productivity of great blue herons throughout Massachusetts show no differences in the numbers of young per nest for herons breeding within or beyond foraging distance of the PSA (MDFW 1979 1980 1981 1982 1983 1984 1985 1986ab 1987 1989 1991 1996) This finding does not support the ERAs qualitative finding that great blue herons face similar to higher risks than American bitterns which are predicted to have high risks (p 12-36)

GE recommends that extrapolations of risk estimates from receptors of interest to other species be omitted from the ERA because they are too uncertain to provide useful information If they are retained GE recommends that the comparisons be accurately characterized as comparisons of potential exposure rather than as comparisons of risk Regardless of how the extrapolations are presented however uncertainties should be explicitly reported including both the inability of the analysis to account for interspecies differences in toxicological sensitivity and cases where available field data contradict the extrapolated findings

262 Extrapolations to Downstream Reaches The field studies surveys and sampling program conducted for the ERA primarily focus on the PSA In an effort to apply the analyses across the entire study area the ERA extrapolates risks downstream of the PSA for seven receptors (benthic invertebrates amphibians warm water fish trout mink otter and bald eagles) For each of these groups the ERA identifies a maximum acceptable threshold concentration (MATC) for total PCBs (tPCBs) Each MATC is then compared to exposure concentrations for individual river and floodplain reaches downstream of Woods Pond to Long Island Sound Areas where exposure concentrations exceed the MATCs are interpreted as indicating potential risks

GE recommends several improvements in this approach (a) revision of the MATCs (b) improved spatial resolution of the overlap between predictions of risk to each receptor and the availability of suitable habitat for those receptors and (c) an explicit discussion of the uncertainties associated with these extrapolations In addition more complete documentation of the methodologies and assumptions employed would enhance the transparency of the analysis

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First several of the MATCs (eg for benthic invertebrates amphibians fish and bald eagles) are not supported by the site-specific studies or the scientific literature Specific concerns related to the basis for these MATCs are discussed below in Sections 311 (benthic invertebrates) 321 amp 322 (amphibians) 332 amp 333 (fish) and 3822 (bald eagles) GE recommends that these MATCs be revised

Second the applicability of the benchmark comparisons for each of the seven receptors should also be considered relative to the available habitat for such receptors in the downstream reaches For example although the MATC for amphibians was developed based on sediment tPCB concentrations in breeding ponds it was applied downstream of Woods Pond to soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data in the downstream reaches (p 12-15) Although such data may be lacking the ERA should make clear that the extrapolation applies only to sediment in potential floodplain ponds downstream of Woods Pond In addition risks to mink otters and bald eagles are evaluated for all reaches of the river with adequate data on exposure concentrations regardless of habitat Restricting the assessment of risks for these receptors to those reaches with suitable habitat would further improve the accuracy of these extrapolations

Third uncertainties in the extrapolations should be discussed and the results should be subjected to a separate weight-of-evidence evaluation

Finally the ERA does not provide enough information regarding the actual methodologies and assumptions used in the analysis of risks downstream of Woods Pond Transparency in this analysis is of paramount importance given the potential influence and use of these extrapolated risk results In particular the ERA should report the actual exposure concentrations used and whether they are spatially weighted averages arithmetic averages 95 upper confidence limits (UCLs) maxima etc In addition EPA should provide at least general information regarding the suitability of the downstream habitat for these receptors or where such information does not exist acknowledge that habitat has not been evaluated and could have a significant effect on any risks downstream of Woods Pond

27 Characterization of GEs Position In several places (pp 2-60 2-61) the ERA characterizes GEs position GE requests that such descriptions of GEs position be removed from the ERA GE will present its position in its comments during the public comment period andor to the Peer Review Panel

28 Non-PCB Constituents The ERA covers the Rest of River which is defined in the Consent Decree (Paragraph 6) as the Housatonic River and its sediments and floodplain areas downstream of the Confluence of the East and West Branches of the Housatonic River including backwaters except for ActualPotential Lawns to the extent that such areas are areas to which Waste Materials that originated at the GE Plant Area have migrated and which are being investigated or remediated pursuant to this Consent Decree (emphasis added) The Revised RCRA Permit contains a similar definition (Definition 19) limiting the Rest of River areas to areas to which releases of hazardous wastes andor hazardous constituents are migrating or have migrated from the GE Facility

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The ERA recognizes that the Rest of River includes areas of the Housatonic River and its sediments and floodplain (except ActualPotential Lawns) in which contaminants migrating from the GE facility are located (p 1-2) However it includes as COPCs a number of non-PCB constituents that are or may not be related to releases from the GE facility These include for various media numerous polycyclic aromatic hydrocarbons (PAHs) and other semi-volatile organic compounds (SVOCs) dioxins and furans several metals and (for fish) certain pesticides (Tables 24-2 through 24-5) There are multiple potential sources of these constituents in the Rest of River area not just releases from the GE facility

To avoid any confusion the ERA should make clear in its discussions of the COPCs (Sections 231 and 243) that while several COPCs other than PCBs have been selected for the ERA there are multiple potential sources of these constituents and hence there is no evidence demonstrating that the occurrence of these COPCs in the Rest of River area is necessarily derived from releases attributable to GE

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3 Specific Comments

31 Benthic Invertebrates In its assessment of benthic invertebrates the ERA derives toxicity thresholds (MATCs) of 3 mgkg tPCB in both tissue (based on the literature) and sediments (based on the results of toxicity and benthic community studies) GE believes that these thresholds should be reevaluated As discussed in this section GE urges EPA to make the following changes to the ERAs assessment of benthic invertebrates (a) use a different data set to calculate sediment-based toxicity thresholds (b) take adequate account of sediment grain size in interpreting the benthic community and toxicity test results (c) reduce the emphasis on Sediment Quality Values and the Toxicity Identification Evaluation (TIE) results (d) recognize a number of additional specified uncertainties and (e) clarify or provide additional information on certain issues

311 Concentration-Response Analysis to Derive Sediment Toxicity Thresholds The ERA concludes that the toxicity studies showed ecologically significant effects at sediment tPCB concentrations of 3 mgkg or higher (pp 3-71 D-98) the proposed MATC for sediment This proposed toxicity threshold is apparently based on LCso and ICso values from laboratory studies that were calculated based on the median values of multiple grab samples (p D-10) (some of which were collected independently of the laboratory bioassays) rather than based on measured concentrations of PCBs in sediments actually used in these bioassays The use of these unrelated data as a basis for establishing exposure levels in laboratory bioassays is of concern given that PCB concentrations in sediments of the Housatonic River can vary by orders of magnitude over very small spatial and temporal scales (pp D-26 to D-28) The rationale given for this method is that combining data from sampling events that are approximately (but not exactly) synoptic with the effects data more accurately portrays the COC concentrations at each station (p D-27) This approach may provide an indication of PCB concentrations in the vicinity of a station over time but it does not provide a better measure of PCB concentrations in the specific composites used in the bioassays than would a direct measure of PCBs in the sediments used in the bioassays For some stations concentrations measured directly from the composites are in fact substantially different than those derived from other collection efforts (Figures D3-1 through D3-5 Stations 7 and 8A) resulting in variability which likely substantially affects the exposure-response analyses and resulting LCsos and ICsoS Because of this variability it is important that effects levels for bioassay tests be calculated from the data that represent the concentrations to which these organisms were actually exposed

GE recommends that the ERA be revised to calculate the No Observed Adverse Effect Levels (NOAELs) Lowest Observed Adverse Effect Levels (LOAELs) and LCsoICso values for the laboratory bioassays (Tables D4-2 and D4-3) based on the synoptic values derived directly from the composite samples for the laboratory bioassays because these values best represent the exposures to the test organisms The LCao and IC20 values should also be revised in a similar manner as should the linear regression models (Table D4-4 Figure D4-5)

312 Effects of Grain Size on Study Interpretation Grain size is a significant variable that can impact both benthic community structure and the endpoints evaluated in the laboratory toxicity studies However in several instances the ERA does not adequately consider the effects of grain size in interpreting the study results

The ERA states that the benthic community data indicated that five of the six stations with median tPCB concentrations above 5 mgkg had significant benthic community alteration (p D-98) Those same five stations had coarse-grained sediments (see Figures D4-6 and D4-7) The one fine-grained station with median tPCB concentrations greater than 5 mgkg (Station 8) had higher species richness and abundance than the coarse-grained stations and was not significantly different from the reference stations (see Figures D4-6 D4-7 and D4-15) Benthic invertebrates tend to be the least diverse and the least abundant in sand likely due to its instability (Ward 1992 Minshall 1984 Allan 1995) Thus even in the absence of PCBs the diversity and abundance of invertebrates would be expected to be lower at the coarse-grained stations In these circumstances it is at least equally likely that grain size rather than PCB concentration explains the spatial variations in benthic community structure As a result the statements throughout the ERA regarding the high level of confidence in the conclusion that benthic invertebrates in the Housatonic River experience unacceptable risks due to tPCBs (eg p 12-55) are not be supported Those statements should be revised to recognize the confounding impacts and uncertainty associated with grain size effects and to note that as a result the benthic community data do not provide conclusive evidence of tPCB effects on changes in community structure

Similar concerns apply to the bioassay test The reference stations used in the bioassay test (Al and A3) are coarse-grained (Figure D2-2) whereas the treatment stations showing the highest levels of response (Stations 7 8 and 8A) are fine-grained Statistical analyses and the weight of evidence evaluation are based on comparisons made between Housatonic River sediment stations and references regardless of grain size (Table D3-4 and Figure D4-15) The uncertainty associated with comparing the toxicity of fine-grained stations to coarse-grained reference treatments should be acknowledged

313 Use of Sediment Quality Values and Toxicity Identification Evaluation in the Weight-of-Evidence

The ERA also relies on published Sediment Quality Values (SQVs) to support a sediment toxicity threshold value of 3 to 5 mgkg (pp 3-71 D-98) SQVs are generic in nature and therefore are primarily appropriate in screening-level ERAs when no site-specific data are available (see eg Long et al 1995) Given the availability of substantial site-specific data the generic SQVs should not be used at all or at a minimum given very low weight and the references to them should be removed from the conclusions

The ERA also gives moderate weight to the results of the Toxicity Identification Evaluation (TIE) (Table D4-5) The ERA concludes from this Phase I TIE that PCBs may be the main causal agent in the toxicity studies (p D-78) However the TIE was not a definitive study and was not designed to provide an independent evaluation of effects and the results of the TIE are inconclusive showing only that non-polar organic chemicals were likely responsible for the observed toxicity As a result while the results of the TIE provide some evidence as to the degree to which observed effects can be linked to PCBs rather than other COPCs the TIE study should be removed as a separate line of evidence

314 Need to Acknowledge Additional Uncertainties There are a number of uncertainties associated with the benthic invertebrate studies Some of these are acknowledged in the text (pp D-95 through D-98) but other critical uncertainties are not The text should be revised to acknowledge the following uncertainties

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Lack of concordance between benthic community and sediment toxicity study results At the four stations for which there are both sediment toxicity test data and benthic community data those results are contradictory The sediment toxicity tests show a toxic response for most endpoints (especially at Stations 7 and 8) whereas the benthic community analyses do not (see Figure D4-15) GE recommends that the ERA be revised to discuss this point in the uncertainty section and also to carry this through to the conclusions in terms of the ability to extrapolate the potential for adverse effects to downstream locations

Inconsistent patterns oftPCB concentrations in sediment and tissues The ERA likewise does not discuss the fact that the median tPCB concentrations in sediments and those in tissue are not consistent (eg elevated tPCB concentrations in sediments were not co-located with those in tissue) (compare Figure 33-3 on p 3-18 with Figure 33-6 on p 3-22) These inconsistencies raise questions regarding the reliability of using median sediment concentrations as a measure of exposure for benthic invertebrates They also limit the usefulness of the biota sediment accumulation factors (BSAFs) which range from 08 to 61 (p D-32) in predicting tissue levels from sediment concentrations These inconsistencies should be acknowledged in the discussion of tissue chemistry (Section 335 pp 3-21 and 3-23) and the implications relative to estimating exposure should be addressed in the uncertainty section

Calculation of LC$o and ICso values The toxicity test endpoints presented in Tables D4-1 through D4-3 based on statistical analyses have a number of significant uncertainties Specifically uncertainties are associated with the results in which (a) the chi-square value exceeds the critical value in the derivation of LCjos and LC2os (20 out of 54 endpoints) (b) visual observations rather than the probit analyses were used because the model did not converge (2 out of 54 endpoints) and (c) there was an interrupted dose-response (9 of 54 endpoints) These difficulties with the statistical analyses are indicative of inconsistencies in the dose-response relationships that result in uncertainty surrounding the threshold values These uncertainties should be addressed (Tables D4-1 - D4-3) In addition no explanation is provided for why the highest dose (772 mgkg) for H azteca 48-h survival is excluded from the effects threshold analysis (Table D4-1) Additional information should be included regarding its exclusion or the analyses should be redone using the results of this treatment

Use of single samples to characterize sediment in used in bioassays A discussion of the uncertainty associated with determining exposure values of sediment composites used in toxicity testing based on a single chemistry sample should be provided (p D-17) Alternatively if multiple samples were used to evaluate potential heterogeneity in these composites to confirm that sediment was completely mixed then those data should be provided

315 Need for Additional Clarification and Information This section describes a number of issues for which the next draft of the ERA should provide clarification or additional data or analyses

Tissue effects thresholds from the literature The ERA states that the literature review was focused on Aroclor 1260 and 1254 (p 3-14) It should be revised to state that no effects thresholds were found based on studies with Aroclor 1260 and that only studies of tPCBs Aroclor 1254 and Clophen A50 were used to derive these thresholds The figures summarizing the literature effects thresholds should also be revised to indicate which study is associated with the effects reported (eg in Figure 44-13)

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and to indicate that studies with Clophen A50 are included in the summary In addition congenershyspecific studies should be removed from the literature review (Table D3-5 and Attachment DI) as they are not appropriate surrogates for tPCB toxicity

Multi-dimensional scaling analysis The results of the multi-dimensional scaling (MDS) statistical analyses used to develop Figures D3-15 through D3-17 should be presented This will provide important information regarding the relative contribution of different factors in this multivariate analysis

Derivation of MATCs The ERA does not explain explicitly how the sediment MATC of 3 mgkg tPCB (p 3-72) used to assess the extent of risks downstream from the PSA was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should specifically document the derivation of the MATC value used

32 Amphibians In the assessment of amphibians the ERA derives toxicity thresholds (MATCs) of 1 mgkg in both tissue (based on the literature) and sediments (based on the results of EPAs wood frog study) As discussed below GE believes that neither of these thresholds is supported by the underlying studies and that they should be higher Moreover in evaluating the results of the wood frog study the ERA does not consider certain endpoints (metamorphosis and mortality) that have clear ecological relevance these endpoints should be included in the evaluation In addition as further discussed in these comments we urge EPA to (a) give lower weight to the results of the leopard frog study and explicitly recognize its use of external reference frogs (b) recognize additional specified uncertainties in the amphibian assessment (c) clarify or present additional data or analyses on certain issues (d) modify the extrapolation to reaches downstream of Woods Pond and (e) correct an error in the text1

321 Lack of Literature Support for a Toxicity Threshold of 1 mgkg tPCBs in Tissue The ERA specifies a toxicity threshold of 1 mgkg in tissue based on a review of the literature (pp 4shy75 E-96) The studies and results used in this review are summarized in Figures 44-13 and E3-37 However the two tPCB LOAELs (called LOELs in these figures) below 1 mgkg shown in these figures are not supported by the underlying study (Gutleb et al 2000) One of these effects levels for time to metamorphosis for the African clawed frog is based on exposure to PCB 126 although tissue chemistry was analyzed as tPCBs Comparing tPCB concentrations to effects levels from a study in which larvae were exposed to PCB 126 would substantially overstate tPCB toxicity and hence this effect level should not be used to evaluate potential tPCB effects The second LOAEL for the European common frog is 024 mgkg tPCBs (wet weight2) in tissue (based on exposure to Clophen A50) However at that concentration there was no adverse effect body weight in the exposed frogs was higher not lower than in the control frogs In fact there was no significant effect on body weight at the highest tissue concentration used in this study (112 mgkg tPCBs wet weight) Hence the latter

1 As noted in Section 1 EPA has also agreed to include the frog study sponsored by GE (Resetarits 2002) in the next draft of the ERA In addition GE has recently completed a study of leopard frog egg masses in the PSA and is providing a report on that study to EPA (ARCADIS 2003) That study should likewise be included in the next draft of the ERA

2 As converted from lipid weight in Attachment E2

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value should be reported as an unbounded NOAEL for that endpoint and the value reported as a LOAEL (024 mgkg) should be removed from these figures

Additional concerns associated with the summary of the literature effects are related to the interpretation of the frequency of occurrence of adverse effects (p 4-56 and E-81) First three LOAELs are cited for mortality based on a single experiment (Savage et al 2002) (Figure 4431 p 4shy57 and E3-37 p 60) By definition a LOAEL is the lowest concentration in an experiment for which there is a statistically significant difference relative to the control therefore only the LOAEL at approximately 6 mgkg from this study should be included in this figure When the erroneous LOAEL (Gutleb et al 2000) and the redundant LOAELs (Savage et al 2002) are removed the frequency of adverse effect analysis indicates that 4 out of 12 endpoints (for tPCBs) or 33 demonstrate adverse effects at concentrations greater than 1 mgkg and that in fact no adverse effects are observed below 6 mgkg

In addition the meaning of this frequency of adverse effects is not clear because there are substantive differences between the nature of effects observed For example the endpoints of reduced activity or swimming speed may or may not have the same severity of impact to an individual as increased mortality This distinction is lost in a simple evaluation of frequency of effects between different endpoints in various literature studies

Based on the above discussion the statement that [tjhere were six instances of adverse effects occurring between 1 and 10 mgkg (pp 4-56 and E-81) should be revised For tPCBs there are only three LOAELs (ie incidence of adverse effects) between 1 and 10 mgkg and all them are at or above 6 mgkg The text should be revised accordingly If the interpretation of these studies based on the frequency of adverse effects is retained that text should also be revised and uncertainties associated with direct comparisons of the different kinds of effects included in this analysis should be acknowledged

322 Lack of Support for a Sediment Toxicity Threshold of 1 mgkg Based on Wood Frog Study

The sediment toxicity threshold of 1 mgkg is apparently based primarily on an analysis of the results of EPAs wood frog study However the description of the results of that study states that [e]cologically significant adverse effects in late stage juvenile wood frogs occurred in the sediment tPCB concentration range of 10 to 60 mgkg although responses of lesser magnitude yet statistically significant were observed at 5 mgkg tPCB and lower (p 4-60) The latter statement (which may be the basis for the threshold) is apparently derived from the wood frog NOAELs and LOAELs presented in Table E4-2 However there are several problems or inconsistencies in the derivation of site-specific NOAELs and LOAELs presented in Table E4-2

bull In several instances the NOAELs and LOAELs do not coincide with sediment concentrations that are associated with the effects data For example the spatially weighted mean tPCB value of 136 mgkg is presented as either a NOAEL or LOAEL for all four endpoints in Table E4-2 However it appears that this value is associated with a vernal pool (46-VP-4 Table E2-8) that has no effects data associated with it (see Tables E3-5- E3-6 and E 310 - E3-11)

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bull It appears that the reference WML-1 has been excluded from the calculation of NOAELs and LOAELs for Phase III metamorphs because of zero response at this concentration(Table E4-2) This exclusion is not warranted While the text refers to the tissue tPCB concentration for reference location WML-1 in the Phase III of the wood frog study as anomalous (eg p 4-52) no problems with data quality are reported that would indicate that the organism did not in fact have a tissue burden of 44 mgkg tPCBs As a result responses associated with this exposure level should be considered to represent part of the range of effects and all analyses of exposure and effect should include this reference site Statistical comparisons with a zero value are commonly made using a value marginally greater than zero (eg 000001)

bull Concentration-response relationships for each endpoint were evaluated using both (1) the most synoptic chemistry value paired with each toxicity endpoint (also referred to as vernal pool sediment) and (2) a combined data set used to generate a spatially weighted surface average (pp 4shy16 mdash 4-17) Given the variability in sediment concentrations the samples used in the laboratory toxicity study should not be assumed to be equivalent to the surface weighted average The synoptic (ie vernal pool) data reflect the actual tPCB concentrations measured in sediments used in the laboratory exposures and should thus should be used for analyses of the Phase I wood frog study which was conducted in the laboratory The surface weighted averages should be used for the analysis of Phase II and Phase III studies in which larvae and metamorphs were exposed in the field as they encompass the range of concentrations to which the growing larvae and metamorphs might have been exposed to The NOAELs LOAELs and point estimates for effects concentrations (eg LC50 and LC20) (Table E4-2) should be revised accordingly

bull Table E4-2 states that the reference site had no malformed specimens (Phase II metamorphs percent malformed) In fact Table E3-11 indicates that reference site WML-3 had 29 malformations

Moreover the toxicity threshold for wood frogs was derived based only on endpoints that showed effects The ERA states that if no discern[i]ble differences in effect levels across treatments were observed (ie inadequate range in response variable) the effects endpoint was not considered in the detailed statistical evaluation (p E-90) As a result as discussed in the next section the lack of PCB-related effects for key endpoints (ie mortality and metamorphosis) were not considered in the derivation of the effects threshold Consideration of the results for those omitted endpoints shows further that the sediment MATC of 1 mgkg is too low

We also note that although Appendix E presents tissue-based HQs for leopard frogs and wood frogs (pp E-96 - E-98) Section 12 of the ERA presents only sediment-based HQs (Figures 122-1 and p 12shy7) Tissue concentrations provide a more direct measure of exposure than do sediment concentrations and hence the tissue-based rather than sediment-based HQs should be used in Section 12

323 Need to Consider Additional Relevant Endpoints in Wood Frog Study As noted above in evaluating the results of the wood frog study two endpoints with clear ecological relevance ~ metamorphosis and mortality -- were screened out of the formal concentration-response modeling due to a lack of discern[i]ble differences in effect levels across treatments (p E-90) However these two endpoints integrate other effects (ie the most serious effect of malformations would be reduced metamorphosis and increased mortality) and should be carried through the

concentration-response evaluation If no concentration-response curve can be derived because there were no effects then the highest dose should be treated as a NOAEL for these endpoints the LC50

should be expressed as gt highest dose and both mortality and metamorphosis should be considered subsequently as part of the lines-of-evidence evaluation

324 Evaluation of the Leopard Frog Study EPAs leopard frog study receives the same overall weight (moderatehigh) as its wood frog study in the weight-of evidence-evaluation (Table 45-4 p 4-69) Considering the significant problems with the leopard frog study as detailed in GEs comments on this study (BBL Sciences et al 2003a) it should be accorded a low weight

Moreover the text does not consistently acknowledge that reference frogs for the leopard frog study were obtained from a biological supply company For readers unfamiliar with the underlying study this could lead to misinterpretations of the results presented The text should be modified to clearly represent this aspect of the leopard frog study as well as additional qualifications as follows

bull The first time the study design of the leopard frog study is presented it should be clearly stated that no frogs or eggslarvae were found in the reference areas (p 4-13)

bull The text that describes comparisons between both the toxicity studies and the community evaluations and appropriately matched field references (p 4-27) should be revised to indicate that for the leopard frog study the field reference was limited to sediment not frogs collected from a reference pond

bull Although the text states that reference ponds were surveyed for eggs and larvae it does not indicate that in addition to no eggs or larvae being found at four of nine contaminated sites none were found at the reference sites (p 4-35)

bull Similarly the summary of female leopard frog reproductive fitness identifies all of the Housatonic River sites that were not gravid (did not have eggs mature enough for successful fertilization) (p 4shy30) It should also indicate that R2 (external reference) did not have any successful fertilization

325 Need to Acknowledge Additional Uncertainties While the ERA acknowledges some uncertainties associated with the amphibian studies (pp 4-70 4shy73 E-108-110) other critical uncertainties are not acknowledged For example there are uncertainties associated with the concentration-response analysis (eg ECsos ECaos) based on the poor fit of the data in the probit analysis Contrary to the statement that most endpoints followed a fairly smooth concentration-response (text box p 4-60) Table E4-2 indicates that only one of 11 of the ECsos presented (ie Phase III metamorph percent malformed based on comparisons with the lowest vernal pool sediment tPCB concentration) appears to be appropriately described by the probit analysis The other ECsos were described as (a) outside data range confidence limits increase (111) (b) probit model had poor fit to data confidence limits increase (111) (c) calculated with linear interpolation no confidence limits can be calculated (311) and (d) based on visual inspection of data (511) These uncertainties should be recognized

326 Need for Additional Information There are a number of issues on which we urge EPA to provide additional information in the next draft of the ERA

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Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

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Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

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2 General Comments A number of general issues apply to multiple assessment endpoints or the overall approach used to evaluate risk in this ERA The general issues discussed below include (a) omission of underlying studies and data (b) exclusion of lines of evidence prior to the weight-of-evidence evaluations (c) overemphasis on hazard quotients (HQs) based on modeled exposures and effects (d) exclusion of data quality from the weight-of-evidence evaluations (e) discussion of evidence regarding abundant populations (f) extrapolations across species and reaches (g) characterization of GEs position and (h) treatment of constituents other than polychlorinated biphenyls (PCBs)

21 Underlying Studies and Data Omitted Neither the reports on the studies that form the basis for many of the measurement endpoints nor the underlying database are provided within or in attachments to the ERA In the absence of the underlying studies and data it is not possible to independently validate calculations statistics or interpretation of those studies EPAs (2002b) Guidelines for Ensuring the Quality Objectivity Utility and Integrity of Information Disseminated by the Environmental Protection Agency emphasize the importance of the reproducibility of such information by qualified third parties (EPA 2002b pp 20-21) GE believes that to ensure the transparency of the ERA the underlying study reports and database should be included as appendices to the ERA (in either paper or electronic form) Through that approach if a commenter or member of the Peer Review Panel wishes to evaluate the underlying basis for a statement or conclusion in the ERA the information necessary to do so will be available

22 Exclusion of Lines of Evidence Prior to the Weight-of-Evidence Evaluations The ERA screens out select lines of evidence (mainly some field studies conducted by EPA contractors) prior to the weight-of-evidence evaluations instead of including all available lines of evidence in the weight-of-evidence evaluations In GEs view this practice is not consistent with the purposes of performing a weight-of-evidence evaluation mdash ie to consider the scientific defensibility of all available lines of evidence to reconcile those lines of evidence and to conclude whether significant risk of harm is posed to the environment (Menzie et al 1996) Moreover this approach does not appear to be systematically applied across receptors For example EPAs fish biomass study is excluded from the weight-of-evidence evaluation on the ground that meaningful statistical assessment of PCS or TEQ relationship to fish community parameters was not feasible (p 5-43) However the qualitative observations of amphibian community structure and the minkotter surveys are (appropriately) included in the weight-of-evidence evaluation despite the fact that like the biomass study statistical evaluations of exposure-response are not possible Additionally the avian surveys are not included in the weight-of-evidence evaluations even though they are initially listed as measurement endpoints for evaluating threatened and endangered species (p 11-6)

GE urges EPA to include all available lines of evidence in the weight-of-evidence evaluations These would include all field-based studies that EPA conducted as well as all studies conducted by GE contractors

In addition for some studies (eg EPAs wood frog study and its Phase II fish toxicity study) the draft ERA includes only a subset of the available endpoints in the weight-of-evidence evaluations as

discussed further in Section 3 In such cases GE urges EPA to evaluate all available and relevant individual lines of evidence from these particular studies

23 Overemphasis on Hazard Quotients The ERA derives Hazard Quotients (HQs) from modeled exposure and effects for the majority of receptors and assesses them as lines of evidence typically according them moderatehigh or high weight In addition the Risk Summary (Section 12) presents the Monte Carlo-based HQs for all receptors to facilitate comparison of risks among aquatic life and wildlife receptors and to give a broad overview of the findings of the risk assessment (p 12-3) Indeed in that section the consideration of other lines of evidence is restricted to a very brief risk characterization that acknowledges that some of the receptors were evaluated based on multiple lines of evidence but does not put the HQs which represent only one of these lines of evidence into this context (pp 12-54 through 12-55) As a result the HQs dominate the presentation of risk in that section

These practices place too much weight and emphasis on the HQs relative to other lines of evidence and tends to obscure the high degree of conservatism and uncertainty associated with the HQs GEs concerns regarding the ERAs interpretation of the HQs and the conservatism and uncertainties present in them are discussed below

231 Interpretation of HQs GE has several concerns with the ERAs interpretation of HQs First in applying the weight-ofshyevidence approach to the HQs the ERA generally does not consider all aspects of the degree of association attribute as defined by Menzie et al (1996) and does not adequately account for limitations in the species-specificity of key input variables Second the HQs are presented in a manner that erroneously suggests that they reflect a full range of individual exposures within the local population Finally the presentation of HQs is confusing in some respects These concerns are further detailed in this section

In applying the weight-of-evidence approach to the HQs the ERA generally assigns moderatehigh or high weight to the great majority of attributes GE believes that a correct application of the Menzie et al (1996) method would yield lower weights for certain of these attributes For example as discussed below the ERA generally scores the HQs moderatehigh or high for the degree of association between the measurement endpoint and the assessment endpoint based primarily on species-specificity whereas GE believes that the HQs should receive low to moderate scores for these attributes

For most of the HQs the rationale provided in the ERA for assignment of a weight related to degree of association refers only to the species-specificity of the study (pp F-52 G-51 H-501-66 J-51 K-68 shyK-69 Tables F4-7 G4-3 H4-314-4 J4-4 K4-3) Based on the Menzie et al (1996) definition as recognized in the ERA (p 2-68) degree of association refers to the extent to which the measurement endpoint is representative of correlated with or applicable to the assessment endpoint in particular with respect to similarity of effect target organ mechanism of action and level of ecological organization (Menzie et al 1996) Hence while species-specificity is part of the definition of degree of association it is not the sole characteristic of that attribute Other aspects of the biological linkage such as the level of ecological organization should also be considered For example EPA guidance states that the assessment endpoints in Superfund ecological risk assessments should address potential

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adverse effects to local populations and communities of biota (EPA 1999 p 5) While that guidance also notes as the ERA states (p 12-47) that impacts on local populations and communities can be estimated by extrapolating from effects on individuals and groups of individuals using a lines-ofshyevidence approach (EPA 1999 p 3) it should be recognized that lines of evidence such as HQ models which do not address population-level effects should receive lower weight in estimating the degree of association with the population-level assessment endpoints Thus GE recommends that the degree of association of each measurement endpoint be evaluated in accordance with the full definition provided by Menzie et al (1996) including consideration of the level of ecological organization

Moreover in evaluating the species-sensitivity aspect of this attribute the ERA does not adequately account for limited species-specificity in the modeled food intake rates fractions of diets derived from the site or effects metrics The food intake rates are calculated using generic allometric equations and input variables that in some cases are not specific to either the preferred prey of the receptor of interest or the receptor itself The assumption that all receptors (except mink) derive 100 of their food from the Primary Study Area (PSA) also does not account for species-specific foraging ranges Although the use of effects metrics based on species in different taxonomic orders from the receptors of interest is recognized in the weight-of-evidence evaluations it only results in scores being reduced from high to moderatehigh A greater decrease in the score is warranted given the significant uncertainties in interspecies extrapolations Hence the most important variables used in the derivation of HQs generally are not species-specific and the weight-of-evidence scores should be lowered on that basis This problem could be ameliorated for some receptors by basing the HQs where possible on site-specific exposure and effects data for the species in question

Further the ERAs presentation of HQ ranges based on distributions of doses (ie lower bound Monte Carlo and upper bound) suggests that the HQs simulate a full range of exposures to individuals within the local population In actuality the upper bound and Monte Carlo HQs presented in the ERA are based on exposures that represent at most a small number of individuals - namely those that derive 100 of their prey from the PSA (except in the case of mink) and only consume prey that contain the highest concentrations of chemicals of potential concern (COPCs) The ERAs use of point estimates for the parameters of proportion of prey derived from the PSA and concentration of COPCs in prey restricts the applicability of the output of the analyses to a very small number of individuals if any to which these exposure parameters might apply As discussed further in Section 2321 below GE recommends use of distributions for these two parameters so that the output of the HQs might be applicable to a broader range of individuals inhabiting the PSA

Finally Figures 122-1 through 122-4 (pp 12-612-912-1112-12) are confusing in that they suggest that absolute values of HQs are comparable across species and across media of interest (eg sediment soil prey) In order to improve the transparency of the risk characterization GE recommends replacing Figures 122-1 through 122-4 with summary tables of the weight-of-evidence evaluations for all assessment endpoints in order to offer a more balanced approach to comparison of risks

232 Conservatism of HQs The ERA states that HQs are not conservative because no safety factors were used to estimate the effects metrics (except in the case of the bald eagle) and uncertainties regarding the exposure model inputs were explicitly propagated through the probability bounds of the exposure model (p 12-10) While GE recognizes that such safety factors are generally not included in the HQ analyses

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considerable conservatism is contributed to the HQs by both the exposure assumptions and the effects metrics If these sources of conservatism are not corrected through alternate assumptions then the conservatism that they contribute should be explicitly acknowledged in the ERA Some of the general sources of conservatism are discussed below while specific comments on the individual receptors are provided in Section 3

2321 Exposure assumptions For all receptors the ERA states that because food intake rates are poorly characterized in the literature it is necessary to model food intake rates based on allometric equations provided in the Wildlife Exposure Factors Handbook (EPA 1993) (eg pp 7-16 8-17 9-13 10-13 11-13) In fact however the EPA (1993) handbook provides measured species-specific food intake rates for all receptor species evaluated in the ERA except tree swallows river otters American bitterns and small-footed myotis According to EPA (1993) measured species-specific values are preferred over modeling intake rates based on allometric equations (p 3-1) GE recommends the use of the species-specific food intake rates reported in the Wildlife Exposure Factors Handbook (EPA 1993) Where that is not or cannot be done the uncertainty associated with using generic allometric equations and input variables that are not species-specific should be discussed and accounted for in the weight-ofshyevidence evaluations

In addition the use of point estimates to characterize the concentrations of COPCs in food and proportion of food derived from the site appears to be inconsistent with the ERAs own criteria for the use of distributions and point estimates The ERA states that point estimates [are used] for minor variables or variables with low coefficients of variation (p 6-17 H-7) Although coefficients of variation are not presented in the ERA and the sensitivity analyses exclude variables characterized with point estimates concentrations of COPCs in food and proportion of diet derived from the site cannot be described as minor because they directly control the magnitude of estimated dose Use of point estimates for these variables prevents uncertainty from being propagated through the probability bounds of the exposure model (p 12-10) and restricts the applicability of the results to those individuals (if any) that only derive their food from the PSA and that always consume food containing the highest concentrations of COPCs In order to align practices applied in the ERA with the stated methodologies GE recommends representation of these variables with appropriate statistical distributions

2322 Effects metrics Many aspects of the effects metrics also contribute to conservatism and uncertainty in the HQs As described in Section 3 these limitations include (for various receptors) the absence of clear documentation of the practices employed in development of the effects metrics lack of support by the underlying studies or failure to reflect the full body of toxicological literature andor lack of acknowledgment of important sources of uncertainty GE recommends revision of the effects metrics in the ERA as discussed in Section 3

The ERA (eg p 6-20) also states that in all cases effects metrics were consistent with the metrics used in the exposure analysis However the ways in which they are consistent are not defined While the effects metrics and exposure analyses are consistent with respect to units (eg mgkg-day) in many cases they are inconsistent with respect to species exposure duration and dosing regime For example an effect metric based on a domesticated species (ie white leghorn chickens) cannot be

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considered consistent with exposure metrics for wild avian receptors GE recommends revising the above statement so that it specifies the ways in which effects metrics are consistent with exposure metrics GE also recommends that the weight-of-evidence evaluations be modified to account for inconsistencies with respect to species exposure duration and dosing regime

24 Exclusion of Data Quality from Weight-of-Evidence Evaluations Based on Menzie et als (1996) quantitative weight-of-evidence approach data quality is one of the most important attributes in determining the scientific defensibility of a measurement endpoint Nonetheless the ERA does not include data quality as an attribute in the weight-of-evidence evaluations Instead the ERA asserts that all studies used in the ERA (except those conducted by GE contractors) have adequate data quality (p 2-70) However the criteria for determining the adequacy of data quality are not defined the process and outcome of a data quality evaluation are not provided and the underlying studies and data are not provided Consequently it is not possible to verify the validity of the assumption that all data have adequate quality In addition this approach implies that data quality for all measurement endpoints based on EPAs studies are equal In fact data quality varies considerably among the underlying studies For example errors and inconsistencies in the databases and analyses presented in underlying studies were identified in comments that GE has previously submitted to EPA The exclusion of data quality from the weight-of-evidence evaluation prevents EPA from accounting for those differences hi data quality

For these reasons GE urges EPA to modify the ERA so that it (a) specifies all necessary information to allow an independent evaluation of data quality for each measurement endpoint (b) includes the attribute of data quality in the weight-of-evidence evaluations and (c) acknowledges any data quality limitations

25 Discussion of Evidence Regarding Abundant Populations Section 12322 of the ERA lists a number of factors that it asserts indicate that studies showing an abundant population of a given receptor at the site do not demonstrate a lack of adverse effects on that population (pp 12-48 through 12-50) The ERA claims that (a) removal of predators compensates for direct effects of contaminants (b) immigration compensates for direct effects of contaminants (c) populations exposed to COPCs may be more vulnerable to other stressors in the future due to chemical adaptation andor immune system effects The application of these theories to a specific site such as the PSA is speculative and unsupported by the underlying studies None of the studies discussed in the ERA was designed to evaluate these types of effects GE believes that this entire discussion should be deleted from the ERA as speculative and unsupported by the data

26 Extrapolation across Species and Reaches The ERA extrapolates findings for risks posed to individual receptors within the PSA to other species and to areas outside the PSA There are several limitations associated with these practices as discussed below

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261 Risk Comparisons across Species The ERA qualitatively extrapolates predicted risks for each receptor to other species within the same feeding guild based on factors that influence exposure to COPCs (eg diet foraging range body weight) There are a number of problems with this approach First in the absence of data on the other species these extrapolations are not supported by any actual evidence Second these extrapolations of risk do not recognize that risk is a function not only of exposure but also of toxicological sensitivity By making the extrapolations based on factors that relate solely to exposure the ERA implies that all species within a feeding guild are equally sensitive to the toxicological effects of the COPCs However as demonstrated by Brunstrom and Lund (1988) toxicological sensitivity can vary by orders of magnitude across species even for species in the same feeding guild and taxonomic order (eg chickens and turkeys) Hence these analyses should not be referred to as comparisons of risk

The interspecies extrapolations also do not account for field data that either support or refute qualitative conclusions regarding relative risks For example data collected by the Massachusetts Division of Fisheries and Wildlife since 1980 on the productivity of great blue herons throughout Massachusetts show no differences in the numbers of young per nest for herons breeding within or beyond foraging distance of the PSA (MDFW 1979 1980 1981 1982 1983 1984 1985 1986ab 1987 1989 1991 1996) This finding does not support the ERAs qualitative finding that great blue herons face similar to higher risks than American bitterns which are predicted to have high risks (p 12-36)

GE recommends that extrapolations of risk estimates from receptors of interest to other species be omitted from the ERA because they are too uncertain to provide useful information If they are retained GE recommends that the comparisons be accurately characterized as comparisons of potential exposure rather than as comparisons of risk Regardless of how the extrapolations are presented however uncertainties should be explicitly reported including both the inability of the analysis to account for interspecies differences in toxicological sensitivity and cases where available field data contradict the extrapolated findings

262 Extrapolations to Downstream Reaches The field studies surveys and sampling program conducted for the ERA primarily focus on the PSA In an effort to apply the analyses across the entire study area the ERA extrapolates risks downstream of the PSA for seven receptors (benthic invertebrates amphibians warm water fish trout mink otter and bald eagles) For each of these groups the ERA identifies a maximum acceptable threshold concentration (MATC) for total PCBs (tPCBs) Each MATC is then compared to exposure concentrations for individual river and floodplain reaches downstream of Woods Pond to Long Island Sound Areas where exposure concentrations exceed the MATCs are interpreted as indicating potential risks

GE recommends several improvements in this approach (a) revision of the MATCs (b) improved spatial resolution of the overlap between predictions of risk to each receptor and the availability of suitable habitat for those receptors and (c) an explicit discussion of the uncertainties associated with these extrapolations In addition more complete documentation of the methodologies and assumptions employed would enhance the transparency of the analysis

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First several of the MATCs (eg for benthic invertebrates amphibians fish and bald eagles) are not supported by the site-specific studies or the scientific literature Specific concerns related to the basis for these MATCs are discussed below in Sections 311 (benthic invertebrates) 321 amp 322 (amphibians) 332 amp 333 (fish) and 3822 (bald eagles) GE recommends that these MATCs be revised

Second the applicability of the benchmark comparisons for each of the seven receptors should also be considered relative to the available habitat for such receptors in the downstream reaches For example although the MATC for amphibians was developed based on sediment tPCB concentrations in breeding ponds it was applied downstream of Woods Pond to soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data in the downstream reaches (p 12-15) Although such data may be lacking the ERA should make clear that the extrapolation applies only to sediment in potential floodplain ponds downstream of Woods Pond In addition risks to mink otters and bald eagles are evaluated for all reaches of the river with adequate data on exposure concentrations regardless of habitat Restricting the assessment of risks for these receptors to those reaches with suitable habitat would further improve the accuracy of these extrapolations

Third uncertainties in the extrapolations should be discussed and the results should be subjected to a separate weight-of-evidence evaluation

Finally the ERA does not provide enough information regarding the actual methodologies and assumptions used in the analysis of risks downstream of Woods Pond Transparency in this analysis is of paramount importance given the potential influence and use of these extrapolated risk results In particular the ERA should report the actual exposure concentrations used and whether they are spatially weighted averages arithmetic averages 95 upper confidence limits (UCLs) maxima etc In addition EPA should provide at least general information regarding the suitability of the downstream habitat for these receptors or where such information does not exist acknowledge that habitat has not been evaluated and could have a significant effect on any risks downstream of Woods Pond

27 Characterization of GEs Position In several places (pp 2-60 2-61) the ERA characterizes GEs position GE requests that such descriptions of GEs position be removed from the ERA GE will present its position in its comments during the public comment period andor to the Peer Review Panel

28 Non-PCB Constituents The ERA covers the Rest of River which is defined in the Consent Decree (Paragraph 6) as the Housatonic River and its sediments and floodplain areas downstream of the Confluence of the East and West Branches of the Housatonic River including backwaters except for ActualPotential Lawns to the extent that such areas are areas to which Waste Materials that originated at the GE Plant Area have migrated and which are being investigated or remediated pursuant to this Consent Decree (emphasis added) The Revised RCRA Permit contains a similar definition (Definition 19) limiting the Rest of River areas to areas to which releases of hazardous wastes andor hazardous constituents are migrating or have migrated from the GE Facility

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The ERA recognizes that the Rest of River includes areas of the Housatonic River and its sediments and floodplain (except ActualPotential Lawns) in which contaminants migrating from the GE facility are located (p 1-2) However it includes as COPCs a number of non-PCB constituents that are or may not be related to releases from the GE facility These include for various media numerous polycyclic aromatic hydrocarbons (PAHs) and other semi-volatile organic compounds (SVOCs) dioxins and furans several metals and (for fish) certain pesticides (Tables 24-2 through 24-5) There are multiple potential sources of these constituents in the Rest of River area not just releases from the GE facility

To avoid any confusion the ERA should make clear in its discussions of the COPCs (Sections 231 and 243) that while several COPCs other than PCBs have been selected for the ERA there are multiple potential sources of these constituents and hence there is no evidence demonstrating that the occurrence of these COPCs in the Rest of River area is necessarily derived from releases attributable to GE

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3 Specific Comments

31 Benthic Invertebrates In its assessment of benthic invertebrates the ERA derives toxicity thresholds (MATCs) of 3 mgkg tPCB in both tissue (based on the literature) and sediments (based on the results of toxicity and benthic community studies) GE believes that these thresholds should be reevaluated As discussed in this section GE urges EPA to make the following changes to the ERAs assessment of benthic invertebrates (a) use a different data set to calculate sediment-based toxicity thresholds (b) take adequate account of sediment grain size in interpreting the benthic community and toxicity test results (c) reduce the emphasis on Sediment Quality Values and the Toxicity Identification Evaluation (TIE) results (d) recognize a number of additional specified uncertainties and (e) clarify or provide additional information on certain issues

311 Concentration-Response Analysis to Derive Sediment Toxicity Thresholds The ERA concludes that the toxicity studies showed ecologically significant effects at sediment tPCB concentrations of 3 mgkg or higher (pp 3-71 D-98) the proposed MATC for sediment This proposed toxicity threshold is apparently based on LCso and ICso values from laboratory studies that were calculated based on the median values of multiple grab samples (p D-10) (some of which were collected independently of the laboratory bioassays) rather than based on measured concentrations of PCBs in sediments actually used in these bioassays The use of these unrelated data as a basis for establishing exposure levels in laboratory bioassays is of concern given that PCB concentrations in sediments of the Housatonic River can vary by orders of magnitude over very small spatial and temporal scales (pp D-26 to D-28) The rationale given for this method is that combining data from sampling events that are approximately (but not exactly) synoptic with the effects data more accurately portrays the COC concentrations at each station (p D-27) This approach may provide an indication of PCB concentrations in the vicinity of a station over time but it does not provide a better measure of PCB concentrations in the specific composites used in the bioassays than would a direct measure of PCBs in the sediments used in the bioassays For some stations concentrations measured directly from the composites are in fact substantially different than those derived from other collection efforts (Figures D3-1 through D3-5 Stations 7 and 8A) resulting in variability which likely substantially affects the exposure-response analyses and resulting LCsos and ICsoS Because of this variability it is important that effects levels for bioassay tests be calculated from the data that represent the concentrations to which these organisms were actually exposed

GE recommends that the ERA be revised to calculate the No Observed Adverse Effect Levels (NOAELs) Lowest Observed Adverse Effect Levels (LOAELs) and LCsoICso values for the laboratory bioassays (Tables D4-2 and D4-3) based on the synoptic values derived directly from the composite samples for the laboratory bioassays because these values best represent the exposures to the test organisms The LCao and IC20 values should also be revised in a similar manner as should the linear regression models (Table D4-4 Figure D4-5)

312 Effects of Grain Size on Study Interpretation Grain size is a significant variable that can impact both benthic community structure and the endpoints evaluated in the laboratory toxicity studies However in several instances the ERA does not adequately consider the effects of grain size in interpreting the study results

The ERA states that the benthic community data indicated that five of the six stations with median tPCB concentrations above 5 mgkg had significant benthic community alteration (p D-98) Those same five stations had coarse-grained sediments (see Figures D4-6 and D4-7) The one fine-grained station with median tPCB concentrations greater than 5 mgkg (Station 8) had higher species richness and abundance than the coarse-grained stations and was not significantly different from the reference stations (see Figures D4-6 D4-7 and D4-15) Benthic invertebrates tend to be the least diverse and the least abundant in sand likely due to its instability (Ward 1992 Minshall 1984 Allan 1995) Thus even in the absence of PCBs the diversity and abundance of invertebrates would be expected to be lower at the coarse-grained stations In these circumstances it is at least equally likely that grain size rather than PCB concentration explains the spatial variations in benthic community structure As a result the statements throughout the ERA regarding the high level of confidence in the conclusion that benthic invertebrates in the Housatonic River experience unacceptable risks due to tPCBs (eg p 12-55) are not be supported Those statements should be revised to recognize the confounding impacts and uncertainty associated with grain size effects and to note that as a result the benthic community data do not provide conclusive evidence of tPCB effects on changes in community structure

Similar concerns apply to the bioassay test The reference stations used in the bioassay test (Al and A3) are coarse-grained (Figure D2-2) whereas the treatment stations showing the highest levels of response (Stations 7 8 and 8A) are fine-grained Statistical analyses and the weight of evidence evaluation are based on comparisons made between Housatonic River sediment stations and references regardless of grain size (Table D3-4 and Figure D4-15) The uncertainty associated with comparing the toxicity of fine-grained stations to coarse-grained reference treatments should be acknowledged

313 Use of Sediment Quality Values and Toxicity Identification Evaluation in the Weight-of-Evidence

The ERA also relies on published Sediment Quality Values (SQVs) to support a sediment toxicity threshold value of 3 to 5 mgkg (pp 3-71 D-98) SQVs are generic in nature and therefore are primarily appropriate in screening-level ERAs when no site-specific data are available (see eg Long et al 1995) Given the availability of substantial site-specific data the generic SQVs should not be used at all or at a minimum given very low weight and the references to them should be removed from the conclusions

The ERA also gives moderate weight to the results of the Toxicity Identification Evaluation (TIE) (Table D4-5) The ERA concludes from this Phase I TIE that PCBs may be the main causal agent in the toxicity studies (p D-78) However the TIE was not a definitive study and was not designed to provide an independent evaluation of effects and the results of the TIE are inconclusive showing only that non-polar organic chemicals were likely responsible for the observed toxicity As a result while the results of the TIE provide some evidence as to the degree to which observed effects can be linked to PCBs rather than other COPCs the TIE study should be removed as a separate line of evidence

314 Need to Acknowledge Additional Uncertainties There are a number of uncertainties associated with the benthic invertebrate studies Some of these are acknowledged in the text (pp D-95 through D-98) but other critical uncertainties are not The text should be revised to acknowledge the following uncertainties

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Lack of concordance between benthic community and sediment toxicity study results At the four stations for which there are both sediment toxicity test data and benthic community data those results are contradictory The sediment toxicity tests show a toxic response for most endpoints (especially at Stations 7 and 8) whereas the benthic community analyses do not (see Figure D4-15) GE recommends that the ERA be revised to discuss this point in the uncertainty section and also to carry this through to the conclusions in terms of the ability to extrapolate the potential for adverse effects to downstream locations

Inconsistent patterns oftPCB concentrations in sediment and tissues The ERA likewise does not discuss the fact that the median tPCB concentrations in sediments and those in tissue are not consistent (eg elevated tPCB concentrations in sediments were not co-located with those in tissue) (compare Figure 33-3 on p 3-18 with Figure 33-6 on p 3-22) These inconsistencies raise questions regarding the reliability of using median sediment concentrations as a measure of exposure for benthic invertebrates They also limit the usefulness of the biota sediment accumulation factors (BSAFs) which range from 08 to 61 (p D-32) in predicting tissue levels from sediment concentrations These inconsistencies should be acknowledged in the discussion of tissue chemistry (Section 335 pp 3-21 and 3-23) and the implications relative to estimating exposure should be addressed in the uncertainty section

Calculation of LC$o and ICso values The toxicity test endpoints presented in Tables D4-1 through D4-3 based on statistical analyses have a number of significant uncertainties Specifically uncertainties are associated with the results in which (a) the chi-square value exceeds the critical value in the derivation of LCjos and LC2os (20 out of 54 endpoints) (b) visual observations rather than the probit analyses were used because the model did not converge (2 out of 54 endpoints) and (c) there was an interrupted dose-response (9 of 54 endpoints) These difficulties with the statistical analyses are indicative of inconsistencies in the dose-response relationships that result in uncertainty surrounding the threshold values These uncertainties should be addressed (Tables D4-1 - D4-3) In addition no explanation is provided for why the highest dose (772 mgkg) for H azteca 48-h survival is excluded from the effects threshold analysis (Table D4-1) Additional information should be included regarding its exclusion or the analyses should be redone using the results of this treatment

Use of single samples to characterize sediment in used in bioassays A discussion of the uncertainty associated with determining exposure values of sediment composites used in toxicity testing based on a single chemistry sample should be provided (p D-17) Alternatively if multiple samples were used to evaluate potential heterogeneity in these composites to confirm that sediment was completely mixed then those data should be provided

315 Need for Additional Clarification and Information This section describes a number of issues for which the next draft of the ERA should provide clarification or additional data or analyses

Tissue effects thresholds from the literature The ERA states that the literature review was focused on Aroclor 1260 and 1254 (p 3-14) It should be revised to state that no effects thresholds were found based on studies with Aroclor 1260 and that only studies of tPCBs Aroclor 1254 and Clophen A50 were used to derive these thresholds The figures summarizing the literature effects thresholds should also be revised to indicate which study is associated with the effects reported (eg in Figure 44-13)

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and to indicate that studies with Clophen A50 are included in the summary In addition congenershyspecific studies should be removed from the literature review (Table D3-5 and Attachment DI) as they are not appropriate surrogates for tPCB toxicity

Multi-dimensional scaling analysis The results of the multi-dimensional scaling (MDS) statistical analyses used to develop Figures D3-15 through D3-17 should be presented This will provide important information regarding the relative contribution of different factors in this multivariate analysis

Derivation of MATCs The ERA does not explain explicitly how the sediment MATC of 3 mgkg tPCB (p 3-72) used to assess the extent of risks downstream from the PSA was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should specifically document the derivation of the MATC value used

32 Amphibians In the assessment of amphibians the ERA derives toxicity thresholds (MATCs) of 1 mgkg in both tissue (based on the literature) and sediments (based on the results of EPAs wood frog study) As discussed below GE believes that neither of these thresholds is supported by the underlying studies and that they should be higher Moreover in evaluating the results of the wood frog study the ERA does not consider certain endpoints (metamorphosis and mortality) that have clear ecological relevance these endpoints should be included in the evaluation In addition as further discussed in these comments we urge EPA to (a) give lower weight to the results of the leopard frog study and explicitly recognize its use of external reference frogs (b) recognize additional specified uncertainties in the amphibian assessment (c) clarify or present additional data or analyses on certain issues (d) modify the extrapolation to reaches downstream of Woods Pond and (e) correct an error in the text1

321 Lack of Literature Support for a Toxicity Threshold of 1 mgkg tPCBs in Tissue The ERA specifies a toxicity threshold of 1 mgkg in tissue based on a review of the literature (pp 4shy75 E-96) The studies and results used in this review are summarized in Figures 44-13 and E3-37 However the two tPCB LOAELs (called LOELs in these figures) below 1 mgkg shown in these figures are not supported by the underlying study (Gutleb et al 2000) One of these effects levels for time to metamorphosis for the African clawed frog is based on exposure to PCB 126 although tissue chemistry was analyzed as tPCBs Comparing tPCB concentrations to effects levels from a study in which larvae were exposed to PCB 126 would substantially overstate tPCB toxicity and hence this effect level should not be used to evaluate potential tPCB effects The second LOAEL for the European common frog is 024 mgkg tPCBs (wet weight2) in tissue (based on exposure to Clophen A50) However at that concentration there was no adverse effect body weight in the exposed frogs was higher not lower than in the control frogs In fact there was no significant effect on body weight at the highest tissue concentration used in this study (112 mgkg tPCBs wet weight) Hence the latter

1 As noted in Section 1 EPA has also agreed to include the frog study sponsored by GE (Resetarits 2002) in the next draft of the ERA In addition GE has recently completed a study of leopard frog egg masses in the PSA and is providing a report on that study to EPA (ARCADIS 2003) That study should likewise be included in the next draft of the ERA

2 As converted from lipid weight in Attachment E2

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value should be reported as an unbounded NOAEL for that endpoint and the value reported as a LOAEL (024 mgkg) should be removed from these figures

Additional concerns associated with the summary of the literature effects are related to the interpretation of the frequency of occurrence of adverse effects (p 4-56 and E-81) First three LOAELs are cited for mortality based on a single experiment (Savage et al 2002) (Figure 4431 p 4shy57 and E3-37 p 60) By definition a LOAEL is the lowest concentration in an experiment for which there is a statistically significant difference relative to the control therefore only the LOAEL at approximately 6 mgkg from this study should be included in this figure When the erroneous LOAEL (Gutleb et al 2000) and the redundant LOAELs (Savage et al 2002) are removed the frequency of adverse effect analysis indicates that 4 out of 12 endpoints (for tPCBs) or 33 demonstrate adverse effects at concentrations greater than 1 mgkg and that in fact no adverse effects are observed below 6 mgkg

In addition the meaning of this frequency of adverse effects is not clear because there are substantive differences between the nature of effects observed For example the endpoints of reduced activity or swimming speed may or may not have the same severity of impact to an individual as increased mortality This distinction is lost in a simple evaluation of frequency of effects between different endpoints in various literature studies

Based on the above discussion the statement that [tjhere were six instances of adverse effects occurring between 1 and 10 mgkg (pp 4-56 and E-81) should be revised For tPCBs there are only three LOAELs (ie incidence of adverse effects) between 1 and 10 mgkg and all them are at or above 6 mgkg The text should be revised accordingly If the interpretation of these studies based on the frequency of adverse effects is retained that text should also be revised and uncertainties associated with direct comparisons of the different kinds of effects included in this analysis should be acknowledged

322 Lack of Support for a Sediment Toxicity Threshold of 1 mgkg Based on Wood Frog Study

The sediment toxicity threshold of 1 mgkg is apparently based primarily on an analysis of the results of EPAs wood frog study However the description of the results of that study states that [e]cologically significant adverse effects in late stage juvenile wood frogs occurred in the sediment tPCB concentration range of 10 to 60 mgkg although responses of lesser magnitude yet statistically significant were observed at 5 mgkg tPCB and lower (p 4-60) The latter statement (which may be the basis for the threshold) is apparently derived from the wood frog NOAELs and LOAELs presented in Table E4-2 However there are several problems or inconsistencies in the derivation of site-specific NOAELs and LOAELs presented in Table E4-2

bull In several instances the NOAELs and LOAELs do not coincide with sediment concentrations that are associated with the effects data For example the spatially weighted mean tPCB value of 136 mgkg is presented as either a NOAEL or LOAEL for all four endpoints in Table E4-2 However it appears that this value is associated with a vernal pool (46-VP-4 Table E2-8) that has no effects data associated with it (see Tables E3-5- E3-6 and E 310 - E3-11)

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bull It appears that the reference WML-1 has been excluded from the calculation of NOAELs and LOAELs for Phase III metamorphs because of zero response at this concentration(Table E4-2) This exclusion is not warranted While the text refers to the tissue tPCB concentration for reference location WML-1 in the Phase III of the wood frog study as anomalous (eg p 4-52) no problems with data quality are reported that would indicate that the organism did not in fact have a tissue burden of 44 mgkg tPCBs As a result responses associated with this exposure level should be considered to represent part of the range of effects and all analyses of exposure and effect should include this reference site Statistical comparisons with a zero value are commonly made using a value marginally greater than zero (eg 000001)

bull Concentration-response relationships for each endpoint were evaluated using both (1) the most synoptic chemistry value paired with each toxicity endpoint (also referred to as vernal pool sediment) and (2) a combined data set used to generate a spatially weighted surface average (pp 4shy16 mdash 4-17) Given the variability in sediment concentrations the samples used in the laboratory toxicity study should not be assumed to be equivalent to the surface weighted average The synoptic (ie vernal pool) data reflect the actual tPCB concentrations measured in sediments used in the laboratory exposures and should thus should be used for analyses of the Phase I wood frog study which was conducted in the laboratory The surface weighted averages should be used for the analysis of Phase II and Phase III studies in which larvae and metamorphs were exposed in the field as they encompass the range of concentrations to which the growing larvae and metamorphs might have been exposed to The NOAELs LOAELs and point estimates for effects concentrations (eg LC50 and LC20) (Table E4-2) should be revised accordingly

bull Table E4-2 states that the reference site had no malformed specimens (Phase II metamorphs percent malformed) In fact Table E3-11 indicates that reference site WML-3 had 29 malformations

Moreover the toxicity threshold for wood frogs was derived based only on endpoints that showed effects The ERA states that if no discern[i]ble differences in effect levels across treatments were observed (ie inadequate range in response variable) the effects endpoint was not considered in the detailed statistical evaluation (p E-90) As a result as discussed in the next section the lack of PCB-related effects for key endpoints (ie mortality and metamorphosis) were not considered in the derivation of the effects threshold Consideration of the results for those omitted endpoints shows further that the sediment MATC of 1 mgkg is too low

We also note that although Appendix E presents tissue-based HQs for leopard frogs and wood frogs (pp E-96 - E-98) Section 12 of the ERA presents only sediment-based HQs (Figures 122-1 and p 12shy7) Tissue concentrations provide a more direct measure of exposure than do sediment concentrations and hence the tissue-based rather than sediment-based HQs should be used in Section 12

323 Need to Consider Additional Relevant Endpoints in Wood Frog Study As noted above in evaluating the results of the wood frog study two endpoints with clear ecological relevance ~ metamorphosis and mortality -- were screened out of the formal concentration-response modeling due to a lack of discern[i]ble differences in effect levels across treatments (p E-90) However these two endpoints integrate other effects (ie the most serious effect of malformations would be reduced metamorphosis and increased mortality) and should be carried through the

concentration-response evaluation If no concentration-response curve can be derived because there were no effects then the highest dose should be treated as a NOAEL for these endpoints the LC50

should be expressed as gt highest dose and both mortality and metamorphosis should be considered subsequently as part of the lines-of-evidence evaluation

324 Evaluation of the Leopard Frog Study EPAs leopard frog study receives the same overall weight (moderatehigh) as its wood frog study in the weight-of evidence-evaluation (Table 45-4 p 4-69) Considering the significant problems with the leopard frog study as detailed in GEs comments on this study (BBL Sciences et al 2003a) it should be accorded a low weight

Moreover the text does not consistently acknowledge that reference frogs for the leopard frog study were obtained from a biological supply company For readers unfamiliar with the underlying study this could lead to misinterpretations of the results presented The text should be modified to clearly represent this aspect of the leopard frog study as well as additional qualifications as follows

bull The first time the study design of the leopard frog study is presented it should be clearly stated that no frogs or eggslarvae were found in the reference areas (p 4-13)

bull The text that describes comparisons between both the toxicity studies and the community evaluations and appropriately matched field references (p 4-27) should be revised to indicate that for the leopard frog study the field reference was limited to sediment not frogs collected from a reference pond

bull Although the text states that reference ponds were surveyed for eggs and larvae it does not indicate that in addition to no eggs or larvae being found at four of nine contaminated sites none were found at the reference sites (p 4-35)

bull Similarly the summary of female leopard frog reproductive fitness identifies all of the Housatonic River sites that were not gravid (did not have eggs mature enough for successful fertilization) (p 4shy30) It should also indicate that R2 (external reference) did not have any successful fertilization

325 Need to Acknowledge Additional Uncertainties While the ERA acknowledges some uncertainties associated with the amphibian studies (pp 4-70 4shy73 E-108-110) other critical uncertainties are not acknowledged For example there are uncertainties associated with the concentration-response analysis (eg ECsos ECaos) based on the poor fit of the data in the probit analysis Contrary to the statement that most endpoints followed a fairly smooth concentration-response (text box p 4-60) Table E4-2 indicates that only one of 11 of the ECsos presented (ie Phase III metamorph percent malformed based on comparisons with the lowest vernal pool sediment tPCB concentration) appears to be appropriately described by the probit analysis The other ECsos were described as (a) outside data range confidence limits increase (111) (b) probit model had poor fit to data confidence limits increase (111) (c) calculated with linear interpolation no confidence limits can be calculated (311) and (d) based on visual inspection of data (511) These uncertainties should be recognized

326 Need for Additional Information There are a number of issues on which we urge EPA to provide additional information in the next draft of the ERA

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Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

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Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

discussed further in Section 3 In such cases GE urges EPA to evaluate all available and relevant individual lines of evidence from these particular studies

23 Overemphasis on Hazard Quotients The ERA derives Hazard Quotients (HQs) from modeled exposure and effects for the majority of receptors and assesses them as lines of evidence typically according them moderatehigh or high weight In addition the Risk Summary (Section 12) presents the Monte Carlo-based HQs for all receptors to facilitate comparison of risks among aquatic life and wildlife receptors and to give a broad overview of the findings of the risk assessment (p 12-3) Indeed in that section the consideration of other lines of evidence is restricted to a very brief risk characterization that acknowledges that some of the receptors were evaluated based on multiple lines of evidence but does not put the HQs which represent only one of these lines of evidence into this context (pp 12-54 through 12-55) As a result the HQs dominate the presentation of risk in that section

These practices place too much weight and emphasis on the HQs relative to other lines of evidence and tends to obscure the high degree of conservatism and uncertainty associated with the HQs GEs concerns regarding the ERAs interpretation of the HQs and the conservatism and uncertainties present in them are discussed below

231 Interpretation of HQs GE has several concerns with the ERAs interpretation of HQs First in applying the weight-ofshyevidence approach to the HQs the ERA generally does not consider all aspects of the degree of association attribute as defined by Menzie et al (1996) and does not adequately account for limitations in the species-specificity of key input variables Second the HQs are presented in a manner that erroneously suggests that they reflect a full range of individual exposures within the local population Finally the presentation of HQs is confusing in some respects These concerns are further detailed in this section

In applying the weight-of-evidence approach to the HQs the ERA generally assigns moderatehigh or high weight to the great majority of attributes GE believes that a correct application of the Menzie et al (1996) method would yield lower weights for certain of these attributes For example as discussed below the ERA generally scores the HQs moderatehigh or high for the degree of association between the measurement endpoint and the assessment endpoint based primarily on species-specificity whereas GE believes that the HQs should receive low to moderate scores for these attributes

For most of the HQs the rationale provided in the ERA for assignment of a weight related to degree of association refers only to the species-specificity of the study (pp F-52 G-51 H-501-66 J-51 K-68 shyK-69 Tables F4-7 G4-3 H4-314-4 J4-4 K4-3) Based on the Menzie et al (1996) definition as recognized in the ERA (p 2-68) degree of association refers to the extent to which the measurement endpoint is representative of correlated with or applicable to the assessment endpoint in particular with respect to similarity of effect target organ mechanism of action and level of ecological organization (Menzie et al 1996) Hence while species-specificity is part of the definition of degree of association it is not the sole characteristic of that attribute Other aspects of the biological linkage such as the level of ecological organization should also be considered For example EPA guidance states that the assessment endpoints in Superfund ecological risk assessments should address potential

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adverse effects to local populations and communities of biota (EPA 1999 p 5) While that guidance also notes as the ERA states (p 12-47) that impacts on local populations and communities can be estimated by extrapolating from effects on individuals and groups of individuals using a lines-ofshyevidence approach (EPA 1999 p 3) it should be recognized that lines of evidence such as HQ models which do not address population-level effects should receive lower weight in estimating the degree of association with the population-level assessment endpoints Thus GE recommends that the degree of association of each measurement endpoint be evaluated in accordance with the full definition provided by Menzie et al (1996) including consideration of the level of ecological organization

Moreover in evaluating the species-sensitivity aspect of this attribute the ERA does not adequately account for limited species-specificity in the modeled food intake rates fractions of diets derived from the site or effects metrics The food intake rates are calculated using generic allometric equations and input variables that in some cases are not specific to either the preferred prey of the receptor of interest or the receptor itself The assumption that all receptors (except mink) derive 100 of their food from the Primary Study Area (PSA) also does not account for species-specific foraging ranges Although the use of effects metrics based on species in different taxonomic orders from the receptors of interest is recognized in the weight-of-evidence evaluations it only results in scores being reduced from high to moderatehigh A greater decrease in the score is warranted given the significant uncertainties in interspecies extrapolations Hence the most important variables used in the derivation of HQs generally are not species-specific and the weight-of-evidence scores should be lowered on that basis This problem could be ameliorated for some receptors by basing the HQs where possible on site-specific exposure and effects data for the species in question

Further the ERAs presentation of HQ ranges based on distributions of doses (ie lower bound Monte Carlo and upper bound) suggests that the HQs simulate a full range of exposures to individuals within the local population In actuality the upper bound and Monte Carlo HQs presented in the ERA are based on exposures that represent at most a small number of individuals - namely those that derive 100 of their prey from the PSA (except in the case of mink) and only consume prey that contain the highest concentrations of chemicals of potential concern (COPCs) The ERAs use of point estimates for the parameters of proportion of prey derived from the PSA and concentration of COPCs in prey restricts the applicability of the output of the analyses to a very small number of individuals if any to which these exposure parameters might apply As discussed further in Section 2321 below GE recommends use of distributions for these two parameters so that the output of the HQs might be applicable to a broader range of individuals inhabiting the PSA

Finally Figures 122-1 through 122-4 (pp 12-612-912-1112-12) are confusing in that they suggest that absolute values of HQs are comparable across species and across media of interest (eg sediment soil prey) In order to improve the transparency of the risk characterization GE recommends replacing Figures 122-1 through 122-4 with summary tables of the weight-of-evidence evaluations for all assessment endpoints in order to offer a more balanced approach to comparison of risks

232 Conservatism of HQs The ERA states that HQs are not conservative because no safety factors were used to estimate the effects metrics (except in the case of the bald eagle) and uncertainties regarding the exposure model inputs were explicitly propagated through the probability bounds of the exposure model (p 12-10) While GE recognizes that such safety factors are generally not included in the HQ analyses

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considerable conservatism is contributed to the HQs by both the exposure assumptions and the effects metrics If these sources of conservatism are not corrected through alternate assumptions then the conservatism that they contribute should be explicitly acknowledged in the ERA Some of the general sources of conservatism are discussed below while specific comments on the individual receptors are provided in Section 3

2321 Exposure assumptions For all receptors the ERA states that because food intake rates are poorly characterized in the literature it is necessary to model food intake rates based on allometric equations provided in the Wildlife Exposure Factors Handbook (EPA 1993) (eg pp 7-16 8-17 9-13 10-13 11-13) In fact however the EPA (1993) handbook provides measured species-specific food intake rates for all receptor species evaluated in the ERA except tree swallows river otters American bitterns and small-footed myotis According to EPA (1993) measured species-specific values are preferred over modeling intake rates based on allometric equations (p 3-1) GE recommends the use of the species-specific food intake rates reported in the Wildlife Exposure Factors Handbook (EPA 1993) Where that is not or cannot be done the uncertainty associated with using generic allometric equations and input variables that are not species-specific should be discussed and accounted for in the weight-ofshyevidence evaluations

In addition the use of point estimates to characterize the concentrations of COPCs in food and proportion of food derived from the site appears to be inconsistent with the ERAs own criteria for the use of distributions and point estimates The ERA states that point estimates [are used] for minor variables or variables with low coefficients of variation (p 6-17 H-7) Although coefficients of variation are not presented in the ERA and the sensitivity analyses exclude variables characterized with point estimates concentrations of COPCs in food and proportion of diet derived from the site cannot be described as minor because they directly control the magnitude of estimated dose Use of point estimates for these variables prevents uncertainty from being propagated through the probability bounds of the exposure model (p 12-10) and restricts the applicability of the results to those individuals (if any) that only derive their food from the PSA and that always consume food containing the highest concentrations of COPCs In order to align practices applied in the ERA with the stated methodologies GE recommends representation of these variables with appropriate statistical distributions

2322 Effects metrics Many aspects of the effects metrics also contribute to conservatism and uncertainty in the HQs As described in Section 3 these limitations include (for various receptors) the absence of clear documentation of the practices employed in development of the effects metrics lack of support by the underlying studies or failure to reflect the full body of toxicological literature andor lack of acknowledgment of important sources of uncertainty GE recommends revision of the effects metrics in the ERA as discussed in Section 3

The ERA (eg p 6-20) also states that in all cases effects metrics were consistent with the metrics used in the exposure analysis However the ways in which they are consistent are not defined While the effects metrics and exposure analyses are consistent with respect to units (eg mgkg-day) in many cases they are inconsistent with respect to species exposure duration and dosing regime For example an effect metric based on a domesticated species (ie white leghorn chickens) cannot be

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considered consistent with exposure metrics for wild avian receptors GE recommends revising the above statement so that it specifies the ways in which effects metrics are consistent with exposure metrics GE also recommends that the weight-of-evidence evaluations be modified to account for inconsistencies with respect to species exposure duration and dosing regime

24 Exclusion of Data Quality from Weight-of-Evidence Evaluations Based on Menzie et als (1996) quantitative weight-of-evidence approach data quality is one of the most important attributes in determining the scientific defensibility of a measurement endpoint Nonetheless the ERA does not include data quality as an attribute in the weight-of-evidence evaluations Instead the ERA asserts that all studies used in the ERA (except those conducted by GE contractors) have adequate data quality (p 2-70) However the criteria for determining the adequacy of data quality are not defined the process and outcome of a data quality evaluation are not provided and the underlying studies and data are not provided Consequently it is not possible to verify the validity of the assumption that all data have adequate quality In addition this approach implies that data quality for all measurement endpoints based on EPAs studies are equal In fact data quality varies considerably among the underlying studies For example errors and inconsistencies in the databases and analyses presented in underlying studies were identified in comments that GE has previously submitted to EPA The exclusion of data quality from the weight-of-evidence evaluation prevents EPA from accounting for those differences hi data quality

For these reasons GE urges EPA to modify the ERA so that it (a) specifies all necessary information to allow an independent evaluation of data quality for each measurement endpoint (b) includes the attribute of data quality in the weight-of-evidence evaluations and (c) acknowledges any data quality limitations

25 Discussion of Evidence Regarding Abundant Populations Section 12322 of the ERA lists a number of factors that it asserts indicate that studies showing an abundant population of a given receptor at the site do not demonstrate a lack of adverse effects on that population (pp 12-48 through 12-50) The ERA claims that (a) removal of predators compensates for direct effects of contaminants (b) immigration compensates for direct effects of contaminants (c) populations exposed to COPCs may be more vulnerable to other stressors in the future due to chemical adaptation andor immune system effects The application of these theories to a specific site such as the PSA is speculative and unsupported by the underlying studies None of the studies discussed in the ERA was designed to evaluate these types of effects GE believes that this entire discussion should be deleted from the ERA as speculative and unsupported by the data

26 Extrapolation across Species and Reaches The ERA extrapolates findings for risks posed to individual receptors within the PSA to other species and to areas outside the PSA There are several limitations associated with these practices as discussed below

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261 Risk Comparisons across Species The ERA qualitatively extrapolates predicted risks for each receptor to other species within the same feeding guild based on factors that influence exposure to COPCs (eg diet foraging range body weight) There are a number of problems with this approach First in the absence of data on the other species these extrapolations are not supported by any actual evidence Second these extrapolations of risk do not recognize that risk is a function not only of exposure but also of toxicological sensitivity By making the extrapolations based on factors that relate solely to exposure the ERA implies that all species within a feeding guild are equally sensitive to the toxicological effects of the COPCs However as demonstrated by Brunstrom and Lund (1988) toxicological sensitivity can vary by orders of magnitude across species even for species in the same feeding guild and taxonomic order (eg chickens and turkeys) Hence these analyses should not be referred to as comparisons of risk

The interspecies extrapolations also do not account for field data that either support or refute qualitative conclusions regarding relative risks For example data collected by the Massachusetts Division of Fisheries and Wildlife since 1980 on the productivity of great blue herons throughout Massachusetts show no differences in the numbers of young per nest for herons breeding within or beyond foraging distance of the PSA (MDFW 1979 1980 1981 1982 1983 1984 1985 1986ab 1987 1989 1991 1996) This finding does not support the ERAs qualitative finding that great blue herons face similar to higher risks than American bitterns which are predicted to have high risks (p 12-36)

GE recommends that extrapolations of risk estimates from receptors of interest to other species be omitted from the ERA because they are too uncertain to provide useful information If they are retained GE recommends that the comparisons be accurately characterized as comparisons of potential exposure rather than as comparisons of risk Regardless of how the extrapolations are presented however uncertainties should be explicitly reported including both the inability of the analysis to account for interspecies differences in toxicological sensitivity and cases where available field data contradict the extrapolated findings

262 Extrapolations to Downstream Reaches The field studies surveys and sampling program conducted for the ERA primarily focus on the PSA In an effort to apply the analyses across the entire study area the ERA extrapolates risks downstream of the PSA for seven receptors (benthic invertebrates amphibians warm water fish trout mink otter and bald eagles) For each of these groups the ERA identifies a maximum acceptable threshold concentration (MATC) for total PCBs (tPCBs) Each MATC is then compared to exposure concentrations for individual river and floodplain reaches downstream of Woods Pond to Long Island Sound Areas where exposure concentrations exceed the MATCs are interpreted as indicating potential risks

GE recommends several improvements in this approach (a) revision of the MATCs (b) improved spatial resolution of the overlap between predictions of risk to each receptor and the availability of suitable habitat for those receptors and (c) an explicit discussion of the uncertainties associated with these extrapolations In addition more complete documentation of the methodologies and assumptions employed would enhance the transparency of the analysis

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First several of the MATCs (eg for benthic invertebrates amphibians fish and bald eagles) are not supported by the site-specific studies or the scientific literature Specific concerns related to the basis for these MATCs are discussed below in Sections 311 (benthic invertebrates) 321 amp 322 (amphibians) 332 amp 333 (fish) and 3822 (bald eagles) GE recommends that these MATCs be revised

Second the applicability of the benchmark comparisons for each of the seven receptors should also be considered relative to the available habitat for such receptors in the downstream reaches For example although the MATC for amphibians was developed based on sediment tPCB concentrations in breeding ponds it was applied downstream of Woods Pond to soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data in the downstream reaches (p 12-15) Although such data may be lacking the ERA should make clear that the extrapolation applies only to sediment in potential floodplain ponds downstream of Woods Pond In addition risks to mink otters and bald eagles are evaluated for all reaches of the river with adequate data on exposure concentrations regardless of habitat Restricting the assessment of risks for these receptors to those reaches with suitable habitat would further improve the accuracy of these extrapolations

Third uncertainties in the extrapolations should be discussed and the results should be subjected to a separate weight-of-evidence evaluation

Finally the ERA does not provide enough information regarding the actual methodologies and assumptions used in the analysis of risks downstream of Woods Pond Transparency in this analysis is of paramount importance given the potential influence and use of these extrapolated risk results In particular the ERA should report the actual exposure concentrations used and whether they are spatially weighted averages arithmetic averages 95 upper confidence limits (UCLs) maxima etc In addition EPA should provide at least general information regarding the suitability of the downstream habitat for these receptors or where such information does not exist acknowledge that habitat has not been evaluated and could have a significant effect on any risks downstream of Woods Pond

27 Characterization of GEs Position In several places (pp 2-60 2-61) the ERA characterizes GEs position GE requests that such descriptions of GEs position be removed from the ERA GE will present its position in its comments during the public comment period andor to the Peer Review Panel

28 Non-PCB Constituents The ERA covers the Rest of River which is defined in the Consent Decree (Paragraph 6) as the Housatonic River and its sediments and floodplain areas downstream of the Confluence of the East and West Branches of the Housatonic River including backwaters except for ActualPotential Lawns to the extent that such areas are areas to which Waste Materials that originated at the GE Plant Area have migrated and which are being investigated or remediated pursuant to this Consent Decree (emphasis added) The Revised RCRA Permit contains a similar definition (Definition 19) limiting the Rest of River areas to areas to which releases of hazardous wastes andor hazardous constituents are migrating or have migrated from the GE Facility

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The ERA recognizes that the Rest of River includes areas of the Housatonic River and its sediments and floodplain (except ActualPotential Lawns) in which contaminants migrating from the GE facility are located (p 1-2) However it includes as COPCs a number of non-PCB constituents that are or may not be related to releases from the GE facility These include for various media numerous polycyclic aromatic hydrocarbons (PAHs) and other semi-volatile organic compounds (SVOCs) dioxins and furans several metals and (for fish) certain pesticides (Tables 24-2 through 24-5) There are multiple potential sources of these constituents in the Rest of River area not just releases from the GE facility

To avoid any confusion the ERA should make clear in its discussions of the COPCs (Sections 231 and 243) that while several COPCs other than PCBs have been selected for the ERA there are multiple potential sources of these constituents and hence there is no evidence demonstrating that the occurrence of these COPCs in the Rest of River area is necessarily derived from releases attributable to GE

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3 Specific Comments

31 Benthic Invertebrates In its assessment of benthic invertebrates the ERA derives toxicity thresholds (MATCs) of 3 mgkg tPCB in both tissue (based on the literature) and sediments (based on the results of toxicity and benthic community studies) GE believes that these thresholds should be reevaluated As discussed in this section GE urges EPA to make the following changes to the ERAs assessment of benthic invertebrates (a) use a different data set to calculate sediment-based toxicity thresholds (b) take adequate account of sediment grain size in interpreting the benthic community and toxicity test results (c) reduce the emphasis on Sediment Quality Values and the Toxicity Identification Evaluation (TIE) results (d) recognize a number of additional specified uncertainties and (e) clarify or provide additional information on certain issues

311 Concentration-Response Analysis to Derive Sediment Toxicity Thresholds The ERA concludes that the toxicity studies showed ecologically significant effects at sediment tPCB concentrations of 3 mgkg or higher (pp 3-71 D-98) the proposed MATC for sediment This proposed toxicity threshold is apparently based on LCso and ICso values from laboratory studies that were calculated based on the median values of multiple grab samples (p D-10) (some of which were collected independently of the laboratory bioassays) rather than based on measured concentrations of PCBs in sediments actually used in these bioassays The use of these unrelated data as a basis for establishing exposure levels in laboratory bioassays is of concern given that PCB concentrations in sediments of the Housatonic River can vary by orders of magnitude over very small spatial and temporal scales (pp D-26 to D-28) The rationale given for this method is that combining data from sampling events that are approximately (but not exactly) synoptic with the effects data more accurately portrays the COC concentrations at each station (p D-27) This approach may provide an indication of PCB concentrations in the vicinity of a station over time but it does not provide a better measure of PCB concentrations in the specific composites used in the bioassays than would a direct measure of PCBs in the sediments used in the bioassays For some stations concentrations measured directly from the composites are in fact substantially different than those derived from other collection efforts (Figures D3-1 through D3-5 Stations 7 and 8A) resulting in variability which likely substantially affects the exposure-response analyses and resulting LCsos and ICsoS Because of this variability it is important that effects levels for bioassay tests be calculated from the data that represent the concentrations to which these organisms were actually exposed

GE recommends that the ERA be revised to calculate the No Observed Adverse Effect Levels (NOAELs) Lowest Observed Adverse Effect Levels (LOAELs) and LCsoICso values for the laboratory bioassays (Tables D4-2 and D4-3) based on the synoptic values derived directly from the composite samples for the laboratory bioassays because these values best represent the exposures to the test organisms The LCao and IC20 values should also be revised in a similar manner as should the linear regression models (Table D4-4 Figure D4-5)

312 Effects of Grain Size on Study Interpretation Grain size is a significant variable that can impact both benthic community structure and the endpoints evaluated in the laboratory toxicity studies However in several instances the ERA does not adequately consider the effects of grain size in interpreting the study results

The ERA states that the benthic community data indicated that five of the six stations with median tPCB concentrations above 5 mgkg had significant benthic community alteration (p D-98) Those same five stations had coarse-grained sediments (see Figures D4-6 and D4-7) The one fine-grained station with median tPCB concentrations greater than 5 mgkg (Station 8) had higher species richness and abundance than the coarse-grained stations and was not significantly different from the reference stations (see Figures D4-6 D4-7 and D4-15) Benthic invertebrates tend to be the least diverse and the least abundant in sand likely due to its instability (Ward 1992 Minshall 1984 Allan 1995) Thus even in the absence of PCBs the diversity and abundance of invertebrates would be expected to be lower at the coarse-grained stations In these circumstances it is at least equally likely that grain size rather than PCB concentration explains the spatial variations in benthic community structure As a result the statements throughout the ERA regarding the high level of confidence in the conclusion that benthic invertebrates in the Housatonic River experience unacceptable risks due to tPCBs (eg p 12-55) are not be supported Those statements should be revised to recognize the confounding impacts and uncertainty associated with grain size effects and to note that as a result the benthic community data do not provide conclusive evidence of tPCB effects on changes in community structure

Similar concerns apply to the bioassay test The reference stations used in the bioassay test (Al and A3) are coarse-grained (Figure D2-2) whereas the treatment stations showing the highest levels of response (Stations 7 8 and 8A) are fine-grained Statistical analyses and the weight of evidence evaluation are based on comparisons made between Housatonic River sediment stations and references regardless of grain size (Table D3-4 and Figure D4-15) The uncertainty associated with comparing the toxicity of fine-grained stations to coarse-grained reference treatments should be acknowledged

313 Use of Sediment Quality Values and Toxicity Identification Evaluation in the Weight-of-Evidence

The ERA also relies on published Sediment Quality Values (SQVs) to support a sediment toxicity threshold value of 3 to 5 mgkg (pp 3-71 D-98) SQVs are generic in nature and therefore are primarily appropriate in screening-level ERAs when no site-specific data are available (see eg Long et al 1995) Given the availability of substantial site-specific data the generic SQVs should not be used at all or at a minimum given very low weight and the references to them should be removed from the conclusions

The ERA also gives moderate weight to the results of the Toxicity Identification Evaluation (TIE) (Table D4-5) The ERA concludes from this Phase I TIE that PCBs may be the main causal agent in the toxicity studies (p D-78) However the TIE was not a definitive study and was not designed to provide an independent evaluation of effects and the results of the TIE are inconclusive showing only that non-polar organic chemicals were likely responsible for the observed toxicity As a result while the results of the TIE provide some evidence as to the degree to which observed effects can be linked to PCBs rather than other COPCs the TIE study should be removed as a separate line of evidence

314 Need to Acknowledge Additional Uncertainties There are a number of uncertainties associated with the benthic invertebrate studies Some of these are acknowledged in the text (pp D-95 through D-98) but other critical uncertainties are not The text should be revised to acknowledge the following uncertainties

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Lack of concordance between benthic community and sediment toxicity study results At the four stations for which there are both sediment toxicity test data and benthic community data those results are contradictory The sediment toxicity tests show a toxic response for most endpoints (especially at Stations 7 and 8) whereas the benthic community analyses do not (see Figure D4-15) GE recommends that the ERA be revised to discuss this point in the uncertainty section and also to carry this through to the conclusions in terms of the ability to extrapolate the potential for adverse effects to downstream locations

Inconsistent patterns oftPCB concentrations in sediment and tissues The ERA likewise does not discuss the fact that the median tPCB concentrations in sediments and those in tissue are not consistent (eg elevated tPCB concentrations in sediments were not co-located with those in tissue) (compare Figure 33-3 on p 3-18 with Figure 33-6 on p 3-22) These inconsistencies raise questions regarding the reliability of using median sediment concentrations as a measure of exposure for benthic invertebrates They also limit the usefulness of the biota sediment accumulation factors (BSAFs) which range from 08 to 61 (p D-32) in predicting tissue levels from sediment concentrations These inconsistencies should be acknowledged in the discussion of tissue chemistry (Section 335 pp 3-21 and 3-23) and the implications relative to estimating exposure should be addressed in the uncertainty section

Calculation of LC$o and ICso values The toxicity test endpoints presented in Tables D4-1 through D4-3 based on statistical analyses have a number of significant uncertainties Specifically uncertainties are associated with the results in which (a) the chi-square value exceeds the critical value in the derivation of LCjos and LC2os (20 out of 54 endpoints) (b) visual observations rather than the probit analyses were used because the model did not converge (2 out of 54 endpoints) and (c) there was an interrupted dose-response (9 of 54 endpoints) These difficulties with the statistical analyses are indicative of inconsistencies in the dose-response relationships that result in uncertainty surrounding the threshold values These uncertainties should be addressed (Tables D4-1 - D4-3) In addition no explanation is provided for why the highest dose (772 mgkg) for H azteca 48-h survival is excluded from the effects threshold analysis (Table D4-1) Additional information should be included regarding its exclusion or the analyses should be redone using the results of this treatment

Use of single samples to characterize sediment in used in bioassays A discussion of the uncertainty associated with determining exposure values of sediment composites used in toxicity testing based on a single chemistry sample should be provided (p D-17) Alternatively if multiple samples were used to evaluate potential heterogeneity in these composites to confirm that sediment was completely mixed then those data should be provided

315 Need for Additional Clarification and Information This section describes a number of issues for which the next draft of the ERA should provide clarification or additional data or analyses

Tissue effects thresholds from the literature The ERA states that the literature review was focused on Aroclor 1260 and 1254 (p 3-14) It should be revised to state that no effects thresholds were found based on studies with Aroclor 1260 and that only studies of tPCBs Aroclor 1254 and Clophen A50 were used to derive these thresholds The figures summarizing the literature effects thresholds should also be revised to indicate which study is associated with the effects reported (eg in Figure 44-13)

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and to indicate that studies with Clophen A50 are included in the summary In addition congenershyspecific studies should be removed from the literature review (Table D3-5 and Attachment DI) as they are not appropriate surrogates for tPCB toxicity

Multi-dimensional scaling analysis The results of the multi-dimensional scaling (MDS) statistical analyses used to develop Figures D3-15 through D3-17 should be presented This will provide important information regarding the relative contribution of different factors in this multivariate analysis

Derivation of MATCs The ERA does not explain explicitly how the sediment MATC of 3 mgkg tPCB (p 3-72) used to assess the extent of risks downstream from the PSA was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should specifically document the derivation of the MATC value used

32 Amphibians In the assessment of amphibians the ERA derives toxicity thresholds (MATCs) of 1 mgkg in both tissue (based on the literature) and sediments (based on the results of EPAs wood frog study) As discussed below GE believes that neither of these thresholds is supported by the underlying studies and that they should be higher Moreover in evaluating the results of the wood frog study the ERA does not consider certain endpoints (metamorphosis and mortality) that have clear ecological relevance these endpoints should be included in the evaluation In addition as further discussed in these comments we urge EPA to (a) give lower weight to the results of the leopard frog study and explicitly recognize its use of external reference frogs (b) recognize additional specified uncertainties in the amphibian assessment (c) clarify or present additional data or analyses on certain issues (d) modify the extrapolation to reaches downstream of Woods Pond and (e) correct an error in the text1

321 Lack of Literature Support for a Toxicity Threshold of 1 mgkg tPCBs in Tissue The ERA specifies a toxicity threshold of 1 mgkg in tissue based on a review of the literature (pp 4shy75 E-96) The studies and results used in this review are summarized in Figures 44-13 and E3-37 However the two tPCB LOAELs (called LOELs in these figures) below 1 mgkg shown in these figures are not supported by the underlying study (Gutleb et al 2000) One of these effects levels for time to metamorphosis for the African clawed frog is based on exposure to PCB 126 although tissue chemistry was analyzed as tPCBs Comparing tPCB concentrations to effects levels from a study in which larvae were exposed to PCB 126 would substantially overstate tPCB toxicity and hence this effect level should not be used to evaluate potential tPCB effects The second LOAEL for the European common frog is 024 mgkg tPCBs (wet weight2) in tissue (based on exposure to Clophen A50) However at that concentration there was no adverse effect body weight in the exposed frogs was higher not lower than in the control frogs In fact there was no significant effect on body weight at the highest tissue concentration used in this study (112 mgkg tPCBs wet weight) Hence the latter

1 As noted in Section 1 EPA has also agreed to include the frog study sponsored by GE (Resetarits 2002) in the next draft of the ERA In addition GE has recently completed a study of leopard frog egg masses in the PSA and is providing a report on that study to EPA (ARCADIS 2003) That study should likewise be included in the next draft of the ERA

2 As converted from lipid weight in Attachment E2

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value should be reported as an unbounded NOAEL for that endpoint and the value reported as a LOAEL (024 mgkg) should be removed from these figures

Additional concerns associated with the summary of the literature effects are related to the interpretation of the frequency of occurrence of adverse effects (p 4-56 and E-81) First three LOAELs are cited for mortality based on a single experiment (Savage et al 2002) (Figure 4431 p 4shy57 and E3-37 p 60) By definition a LOAEL is the lowest concentration in an experiment for which there is a statistically significant difference relative to the control therefore only the LOAEL at approximately 6 mgkg from this study should be included in this figure When the erroneous LOAEL (Gutleb et al 2000) and the redundant LOAELs (Savage et al 2002) are removed the frequency of adverse effect analysis indicates that 4 out of 12 endpoints (for tPCBs) or 33 demonstrate adverse effects at concentrations greater than 1 mgkg and that in fact no adverse effects are observed below 6 mgkg

In addition the meaning of this frequency of adverse effects is not clear because there are substantive differences between the nature of effects observed For example the endpoints of reduced activity or swimming speed may or may not have the same severity of impact to an individual as increased mortality This distinction is lost in a simple evaluation of frequency of effects between different endpoints in various literature studies

Based on the above discussion the statement that [tjhere were six instances of adverse effects occurring between 1 and 10 mgkg (pp 4-56 and E-81) should be revised For tPCBs there are only three LOAELs (ie incidence of adverse effects) between 1 and 10 mgkg and all them are at or above 6 mgkg The text should be revised accordingly If the interpretation of these studies based on the frequency of adverse effects is retained that text should also be revised and uncertainties associated with direct comparisons of the different kinds of effects included in this analysis should be acknowledged

322 Lack of Support for a Sediment Toxicity Threshold of 1 mgkg Based on Wood Frog Study

The sediment toxicity threshold of 1 mgkg is apparently based primarily on an analysis of the results of EPAs wood frog study However the description of the results of that study states that [e]cologically significant adverse effects in late stage juvenile wood frogs occurred in the sediment tPCB concentration range of 10 to 60 mgkg although responses of lesser magnitude yet statistically significant were observed at 5 mgkg tPCB and lower (p 4-60) The latter statement (which may be the basis for the threshold) is apparently derived from the wood frog NOAELs and LOAELs presented in Table E4-2 However there are several problems or inconsistencies in the derivation of site-specific NOAELs and LOAELs presented in Table E4-2

bull In several instances the NOAELs and LOAELs do not coincide with sediment concentrations that are associated with the effects data For example the spatially weighted mean tPCB value of 136 mgkg is presented as either a NOAEL or LOAEL for all four endpoints in Table E4-2 However it appears that this value is associated with a vernal pool (46-VP-4 Table E2-8) that has no effects data associated with it (see Tables E3-5- E3-6 and E 310 - E3-11)

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bull It appears that the reference WML-1 has been excluded from the calculation of NOAELs and LOAELs for Phase III metamorphs because of zero response at this concentration(Table E4-2) This exclusion is not warranted While the text refers to the tissue tPCB concentration for reference location WML-1 in the Phase III of the wood frog study as anomalous (eg p 4-52) no problems with data quality are reported that would indicate that the organism did not in fact have a tissue burden of 44 mgkg tPCBs As a result responses associated with this exposure level should be considered to represent part of the range of effects and all analyses of exposure and effect should include this reference site Statistical comparisons with a zero value are commonly made using a value marginally greater than zero (eg 000001)

bull Concentration-response relationships for each endpoint were evaluated using both (1) the most synoptic chemistry value paired with each toxicity endpoint (also referred to as vernal pool sediment) and (2) a combined data set used to generate a spatially weighted surface average (pp 4shy16 mdash 4-17) Given the variability in sediment concentrations the samples used in the laboratory toxicity study should not be assumed to be equivalent to the surface weighted average The synoptic (ie vernal pool) data reflect the actual tPCB concentrations measured in sediments used in the laboratory exposures and should thus should be used for analyses of the Phase I wood frog study which was conducted in the laboratory The surface weighted averages should be used for the analysis of Phase II and Phase III studies in which larvae and metamorphs were exposed in the field as they encompass the range of concentrations to which the growing larvae and metamorphs might have been exposed to The NOAELs LOAELs and point estimates for effects concentrations (eg LC50 and LC20) (Table E4-2) should be revised accordingly

bull Table E4-2 states that the reference site had no malformed specimens (Phase II metamorphs percent malformed) In fact Table E3-11 indicates that reference site WML-3 had 29 malformations

Moreover the toxicity threshold for wood frogs was derived based only on endpoints that showed effects The ERA states that if no discern[i]ble differences in effect levels across treatments were observed (ie inadequate range in response variable) the effects endpoint was not considered in the detailed statistical evaluation (p E-90) As a result as discussed in the next section the lack of PCB-related effects for key endpoints (ie mortality and metamorphosis) were not considered in the derivation of the effects threshold Consideration of the results for those omitted endpoints shows further that the sediment MATC of 1 mgkg is too low

We also note that although Appendix E presents tissue-based HQs for leopard frogs and wood frogs (pp E-96 - E-98) Section 12 of the ERA presents only sediment-based HQs (Figures 122-1 and p 12shy7) Tissue concentrations provide a more direct measure of exposure than do sediment concentrations and hence the tissue-based rather than sediment-based HQs should be used in Section 12

323 Need to Consider Additional Relevant Endpoints in Wood Frog Study As noted above in evaluating the results of the wood frog study two endpoints with clear ecological relevance ~ metamorphosis and mortality -- were screened out of the formal concentration-response modeling due to a lack of discern[i]ble differences in effect levels across treatments (p E-90) However these two endpoints integrate other effects (ie the most serious effect of malformations would be reduced metamorphosis and increased mortality) and should be carried through the

concentration-response evaluation If no concentration-response curve can be derived because there were no effects then the highest dose should be treated as a NOAEL for these endpoints the LC50

should be expressed as gt highest dose and both mortality and metamorphosis should be considered subsequently as part of the lines-of-evidence evaluation

324 Evaluation of the Leopard Frog Study EPAs leopard frog study receives the same overall weight (moderatehigh) as its wood frog study in the weight-of evidence-evaluation (Table 45-4 p 4-69) Considering the significant problems with the leopard frog study as detailed in GEs comments on this study (BBL Sciences et al 2003a) it should be accorded a low weight

Moreover the text does not consistently acknowledge that reference frogs for the leopard frog study were obtained from a biological supply company For readers unfamiliar with the underlying study this could lead to misinterpretations of the results presented The text should be modified to clearly represent this aspect of the leopard frog study as well as additional qualifications as follows

bull The first time the study design of the leopard frog study is presented it should be clearly stated that no frogs or eggslarvae were found in the reference areas (p 4-13)

bull The text that describes comparisons between both the toxicity studies and the community evaluations and appropriately matched field references (p 4-27) should be revised to indicate that for the leopard frog study the field reference was limited to sediment not frogs collected from a reference pond

bull Although the text states that reference ponds were surveyed for eggs and larvae it does not indicate that in addition to no eggs or larvae being found at four of nine contaminated sites none were found at the reference sites (p 4-35)

bull Similarly the summary of female leopard frog reproductive fitness identifies all of the Housatonic River sites that were not gravid (did not have eggs mature enough for successful fertilization) (p 4shy30) It should also indicate that R2 (external reference) did not have any successful fertilization

325 Need to Acknowledge Additional Uncertainties While the ERA acknowledges some uncertainties associated with the amphibian studies (pp 4-70 4shy73 E-108-110) other critical uncertainties are not acknowledged For example there are uncertainties associated with the concentration-response analysis (eg ECsos ECaos) based on the poor fit of the data in the probit analysis Contrary to the statement that most endpoints followed a fairly smooth concentration-response (text box p 4-60) Table E4-2 indicates that only one of 11 of the ECsos presented (ie Phase III metamorph percent malformed based on comparisons with the lowest vernal pool sediment tPCB concentration) appears to be appropriately described by the probit analysis The other ECsos were described as (a) outside data range confidence limits increase (111) (b) probit model had poor fit to data confidence limits increase (111) (c) calculated with linear interpolation no confidence limits can be calculated (311) and (d) based on visual inspection of data (511) These uncertainties should be recognized

326 Need for Additional Information There are a number of issues on which we urge EPA to provide additional information in the next draft of the ERA

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Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

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Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

adverse effects to local populations and communities of biota (EPA 1999 p 5) While that guidance also notes as the ERA states (p 12-47) that impacts on local populations and communities can be estimated by extrapolating from effects on individuals and groups of individuals using a lines-ofshyevidence approach (EPA 1999 p 3) it should be recognized that lines of evidence such as HQ models which do not address population-level effects should receive lower weight in estimating the degree of association with the population-level assessment endpoints Thus GE recommends that the degree of association of each measurement endpoint be evaluated in accordance with the full definition provided by Menzie et al (1996) including consideration of the level of ecological organization

Moreover in evaluating the species-sensitivity aspect of this attribute the ERA does not adequately account for limited species-specificity in the modeled food intake rates fractions of diets derived from the site or effects metrics The food intake rates are calculated using generic allometric equations and input variables that in some cases are not specific to either the preferred prey of the receptor of interest or the receptor itself The assumption that all receptors (except mink) derive 100 of their food from the Primary Study Area (PSA) also does not account for species-specific foraging ranges Although the use of effects metrics based on species in different taxonomic orders from the receptors of interest is recognized in the weight-of-evidence evaluations it only results in scores being reduced from high to moderatehigh A greater decrease in the score is warranted given the significant uncertainties in interspecies extrapolations Hence the most important variables used in the derivation of HQs generally are not species-specific and the weight-of-evidence scores should be lowered on that basis This problem could be ameliorated for some receptors by basing the HQs where possible on site-specific exposure and effects data for the species in question

Further the ERAs presentation of HQ ranges based on distributions of doses (ie lower bound Monte Carlo and upper bound) suggests that the HQs simulate a full range of exposures to individuals within the local population In actuality the upper bound and Monte Carlo HQs presented in the ERA are based on exposures that represent at most a small number of individuals - namely those that derive 100 of their prey from the PSA (except in the case of mink) and only consume prey that contain the highest concentrations of chemicals of potential concern (COPCs) The ERAs use of point estimates for the parameters of proportion of prey derived from the PSA and concentration of COPCs in prey restricts the applicability of the output of the analyses to a very small number of individuals if any to which these exposure parameters might apply As discussed further in Section 2321 below GE recommends use of distributions for these two parameters so that the output of the HQs might be applicable to a broader range of individuals inhabiting the PSA

Finally Figures 122-1 through 122-4 (pp 12-612-912-1112-12) are confusing in that they suggest that absolute values of HQs are comparable across species and across media of interest (eg sediment soil prey) In order to improve the transparency of the risk characterization GE recommends replacing Figures 122-1 through 122-4 with summary tables of the weight-of-evidence evaluations for all assessment endpoints in order to offer a more balanced approach to comparison of risks

232 Conservatism of HQs The ERA states that HQs are not conservative because no safety factors were used to estimate the effects metrics (except in the case of the bald eagle) and uncertainties regarding the exposure model inputs were explicitly propagated through the probability bounds of the exposure model (p 12-10) While GE recognizes that such safety factors are generally not included in the HQ analyses

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considerable conservatism is contributed to the HQs by both the exposure assumptions and the effects metrics If these sources of conservatism are not corrected through alternate assumptions then the conservatism that they contribute should be explicitly acknowledged in the ERA Some of the general sources of conservatism are discussed below while specific comments on the individual receptors are provided in Section 3

2321 Exposure assumptions For all receptors the ERA states that because food intake rates are poorly characterized in the literature it is necessary to model food intake rates based on allometric equations provided in the Wildlife Exposure Factors Handbook (EPA 1993) (eg pp 7-16 8-17 9-13 10-13 11-13) In fact however the EPA (1993) handbook provides measured species-specific food intake rates for all receptor species evaluated in the ERA except tree swallows river otters American bitterns and small-footed myotis According to EPA (1993) measured species-specific values are preferred over modeling intake rates based on allometric equations (p 3-1) GE recommends the use of the species-specific food intake rates reported in the Wildlife Exposure Factors Handbook (EPA 1993) Where that is not or cannot be done the uncertainty associated with using generic allometric equations and input variables that are not species-specific should be discussed and accounted for in the weight-ofshyevidence evaluations

In addition the use of point estimates to characterize the concentrations of COPCs in food and proportion of food derived from the site appears to be inconsistent with the ERAs own criteria for the use of distributions and point estimates The ERA states that point estimates [are used] for minor variables or variables with low coefficients of variation (p 6-17 H-7) Although coefficients of variation are not presented in the ERA and the sensitivity analyses exclude variables characterized with point estimates concentrations of COPCs in food and proportion of diet derived from the site cannot be described as minor because they directly control the magnitude of estimated dose Use of point estimates for these variables prevents uncertainty from being propagated through the probability bounds of the exposure model (p 12-10) and restricts the applicability of the results to those individuals (if any) that only derive their food from the PSA and that always consume food containing the highest concentrations of COPCs In order to align practices applied in the ERA with the stated methodologies GE recommends representation of these variables with appropriate statistical distributions

2322 Effects metrics Many aspects of the effects metrics also contribute to conservatism and uncertainty in the HQs As described in Section 3 these limitations include (for various receptors) the absence of clear documentation of the practices employed in development of the effects metrics lack of support by the underlying studies or failure to reflect the full body of toxicological literature andor lack of acknowledgment of important sources of uncertainty GE recommends revision of the effects metrics in the ERA as discussed in Section 3

The ERA (eg p 6-20) also states that in all cases effects metrics were consistent with the metrics used in the exposure analysis However the ways in which they are consistent are not defined While the effects metrics and exposure analyses are consistent with respect to units (eg mgkg-day) in many cases they are inconsistent with respect to species exposure duration and dosing regime For example an effect metric based on a domesticated species (ie white leghorn chickens) cannot be

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considered consistent with exposure metrics for wild avian receptors GE recommends revising the above statement so that it specifies the ways in which effects metrics are consistent with exposure metrics GE also recommends that the weight-of-evidence evaluations be modified to account for inconsistencies with respect to species exposure duration and dosing regime

24 Exclusion of Data Quality from Weight-of-Evidence Evaluations Based on Menzie et als (1996) quantitative weight-of-evidence approach data quality is one of the most important attributes in determining the scientific defensibility of a measurement endpoint Nonetheless the ERA does not include data quality as an attribute in the weight-of-evidence evaluations Instead the ERA asserts that all studies used in the ERA (except those conducted by GE contractors) have adequate data quality (p 2-70) However the criteria for determining the adequacy of data quality are not defined the process and outcome of a data quality evaluation are not provided and the underlying studies and data are not provided Consequently it is not possible to verify the validity of the assumption that all data have adequate quality In addition this approach implies that data quality for all measurement endpoints based on EPAs studies are equal In fact data quality varies considerably among the underlying studies For example errors and inconsistencies in the databases and analyses presented in underlying studies were identified in comments that GE has previously submitted to EPA The exclusion of data quality from the weight-of-evidence evaluation prevents EPA from accounting for those differences hi data quality

For these reasons GE urges EPA to modify the ERA so that it (a) specifies all necessary information to allow an independent evaluation of data quality for each measurement endpoint (b) includes the attribute of data quality in the weight-of-evidence evaluations and (c) acknowledges any data quality limitations

25 Discussion of Evidence Regarding Abundant Populations Section 12322 of the ERA lists a number of factors that it asserts indicate that studies showing an abundant population of a given receptor at the site do not demonstrate a lack of adverse effects on that population (pp 12-48 through 12-50) The ERA claims that (a) removal of predators compensates for direct effects of contaminants (b) immigration compensates for direct effects of contaminants (c) populations exposed to COPCs may be more vulnerable to other stressors in the future due to chemical adaptation andor immune system effects The application of these theories to a specific site such as the PSA is speculative and unsupported by the underlying studies None of the studies discussed in the ERA was designed to evaluate these types of effects GE believes that this entire discussion should be deleted from the ERA as speculative and unsupported by the data

26 Extrapolation across Species and Reaches The ERA extrapolates findings for risks posed to individual receptors within the PSA to other species and to areas outside the PSA There are several limitations associated with these practices as discussed below

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261 Risk Comparisons across Species The ERA qualitatively extrapolates predicted risks for each receptor to other species within the same feeding guild based on factors that influence exposure to COPCs (eg diet foraging range body weight) There are a number of problems with this approach First in the absence of data on the other species these extrapolations are not supported by any actual evidence Second these extrapolations of risk do not recognize that risk is a function not only of exposure but also of toxicological sensitivity By making the extrapolations based on factors that relate solely to exposure the ERA implies that all species within a feeding guild are equally sensitive to the toxicological effects of the COPCs However as demonstrated by Brunstrom and Lund (1988) toxicological sensitivity can vary by orders of magnitude across species even for species in the same feeding guild and taxonomic order (eg chickens and turkeys) Hence these analyses should not be referred to as comparisons of risk

The interspecies extrapolations also do not account for field data that either support or refute qualitative conclusions regarding relative risks For example data collected by the Massachusetts Division of Fisheries and Wildlife since 1980 on the productivity of great blue herons throughout Massachusetts show no differences in the numbers of young per nest for herons breeding within or beyond foraging distance of the PSA (MDFW 1979 1980 1981 1982 1983 1984 1985 1986ab 1987 1989 1991 1996) This finding does not support the ERAs qualitative finding that great blue herons face similar to higher risks than American bitterns which are predicted to have high risks (p 12-36)

GE recommends that extrapolations of risk estimates from receptors of interest to other species be omitted from the ERA because they are too uncertain to provide useful information If they are retained GE recommends that the comparisons be accurately characterized as comparisons of potential exposure rather than as comparisons of risk Regardless of how the extrapolations are presented however uncertainties should be explicitly reported including both the inability of the analysis to account for interspecies differences in toxicological sensitivity and cases where available field data contradict the extrapolated findings

262 Extrapolations to Downstream Reaches The field studies surveys and sampling program conducted for the ERA primarily focus on the PSA In an effort to apply the analyses across the entire study area the ERA extrapolates risks downstream of the PSA for seven receptors (benthic invertebrates amphibians warm water fish trout mink otter and bald eagles) For each of these groups the ERA identifies a maximum acceptable threshold concentration (MATC) for total PCBs (tPCBs) Each MATC is then compared to exposure concentrations for individual river and floodplain reaches downstream of Woods Pond to Long Island Sound Areas where exposure concentrations exceed the MATCs are interpreted as indicating potential risks

GE recommends several improvements in this approach (a) revision of the MATCs (b) improved spatial resolution of the overlap between predictions of risk to each receptor and the availability of suitable habitat for those receptors and (c) an explicit discussion of the uncertainties associated with these extrapolations In addition more complete documentation of the methodologies and assumptions employed would enhance the transparency of the analysis

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First several of the MATCs (eg for benthic invertebrates amphibians fish and bald eagles) are not supported by the site-specific studies or the scientific literature Specific concerns related to the basis for these MATCs are discussed below in Sections 311 (benthic invertebrates) 321 amp 322 (amphibians) 332 amp 333 (fish) and 3822 (bald eagles) GE recommends that these MATCs be revised

Second the applicability of the benchmark comparisons for each of the seven receptors should also be considered relative to the available habitat for such receptors in the downstream reaches For example although the MATC for amphibians was developed based on sediment tPCB concentrations in breeding ponds it was applied downstream of Woods Pond to soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data in the downstream reaches (p 12-15) Although such data may be lacking the ERA should make clear that the extrapolation applies only to sediment in potential floodplain ponds downstream of Woods Pond In addition risks to mink otters and bald eagles are evaluated for all reaches of the river with adequate data on exposure concentrations regardless of habitat Restricting the assessment of risks for these receptors to those reaches with suitable habitat would further improve the accuracy of these extrapolations

Third uncertainties in the extrapolations should be discussed and the results should be subjected to a separate weight-of-evidence evaluation

Finally the ERA does not provide enough information regarding the actual methodologies and assumptions used in the analysis of risks downstream of Woods Pond Transparency in this analysis is of paramount importance given the potential influence and use of these extrapolated risk results In particular the ERA should report the actual exposure concentrations used and whether they are spatially weighted averages arithmetic averages 95 upper confidence limits (UCLs) maxima etc In addition EPA should provide at least general information regarding the suitability of the downstream habitat for these receptors or where such information does not exist acknowledge that habitat has not been evaluated and could have a significant effect on any risks downstream of Woods Pond

27 Characterization of GEs Position In several places (pp 2-60 2-61) the ERA characterizes GEs position GE requests that such descriptions of GEs position be removed from the ERA GE will present its position in its comments during the public comment period andor to the Peer Review Panel

28 Non-PCB Constituents The ERA covers the Rest of River which is defined in the Consent Decree (Paragraph 6) as the Housatonic River and its sediments and floodplain areas downstream of the Confluence of the East and West Branches of the Housatonic River including backwaters except for ActualPotential Lawns to the extent that such areas are areas to which Waste Materials that originated at the GE Plant Area have migrated and which are being investigated or remediated pursuant to this Consent Decree (emphasis added) The Revised RCRA Permit contains a similar definition (Definition 19) limiting the Rest of River areas to areas to which releases of hazardous wastes andor hazardous constituents are migrating or have migrated from the GE Facility

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The ERA recognizes that the Rest of River includes areas of the Housatonic River and its sediments and floodplain (except ActualPotential Lawns) in which contaminants migrating from the GE facility are located (p 1-2) However it includes as COPCs a number of non-PCB constituents that are or may not be related to releases from the GE facility These include for various media numerous polycyclic aromatic hydrocarbons (PAHs) and other semi-volatile organic compounds (SVOCs) dioxins and furans several metals and (for fish) certain pesticides (Tables 24-2 through 24-5) There are multiple potential sources of these constituents in the Rest of River area not just releases from the GE facility

To avoid any confusion the ERA should make clear in its discussions of the COPCs (Sections 231 and 243) that while several COPCs other than PCBs have been selected for the ERA there are multiple potential sources of these constituents and hence there is no evidence demonstrating that the occurrence of these COPCs in the Rest of River area is necessarily derived from releases attributable to GE

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3 Specific Comments

31 Benthic Invertebrates In its assessment of benthic invertebrates the ERA derives toxicity thresholds (MATCs) of 3 mgkg tPCB in both tissue (based on the literature) and sediments (based on the results of toxicity and benthic community studies) GE believes that these thresholds should be reevaluated As discussed in this section GE urges EPA to make the following changes to the ERAs assessment of benthic invertebrates (a) use a different data set to calculate sediment-based toxicity thresholds (b) take adequate account of sediment grain size in interpreting the benthic community and toxicity test results (c) reduce the emphasis on Sediment Quality Values and the Toxicity Identification Evaluation (TIE) results (d) recognize a number of additional specified uncertainties and (e) clarify or provide additional information on certain issues

311 Concentration-Response Analysis to Derive Sediment Toxicity Thresholds The ERA concludes that the toxicity studies showed ecologically significant effects at sediment tPCB concentrations of 3 mgkg or higher (pp 3-71 D-98) the proposed MATC for sediment This proposed toxicity threshold is apparently based on LCso and ICso values from laboratory studies that were calculated based on the median values of multiple grab samples (p D-10) (some of which were collected independently of the laboratory bioassays) rather than based on measured concentrations of PCBs in sediments actually used in these bioassays The use of these unrelated data as a basis for establishing exposure levels in laboratory bioassays is of concern given that PCB concentrations in sediments of the Housatonic River can vary by orders of magnitude over very small spatial and temporal scales (pp D-26 to D-28) The rationale given for this method is that combining data from sampling events that are approximately (but not exactly) synoptic with the effects data more accurately portrays the COC concentrations at each station (p D-27) This approach may provide an indication of PCB concentrations in the vicinity of a station over time but it does not provide a better measure of PCB concentrations in the specific composites used in the bioassays than would a direct measure of PCBs in the sediments used in the bioassays For some stations concentrations measured directly from the composites are in fact substantially different than those derived from other collection efforts (Figures D3-1 through D3-5 Stations 7 and 8A) resulting in variability which likely substantially affects the exposure-response analyses and resulting LCsos and ICsoS Because of this variability it is important that effects levels for bioassay tests be calculated from the data that represent the concentrations to which these organisms were actually exposed

GE recommends that the ERA be revised to calculate the No Observed Adverse Effect Levels (NOAELs) Lowest Observed Adverse Effect Levels (LOAELs) and LCsoICso values for the laboratory bioassays (Tables D4-2 and D4-3) based on the synoptic values derived directly from the composite samples for the laboratory bioassays because these values best represent the exposures to the test organisms The LCao and IC20 values should also be revised in a similar manner as should the linear regression models (Table D4-4 Figure D4-5)

312 Effects of Grain Size on Study Interpretation Grain size is a significant variable that can impact both benthic community structure and the endpoints evaluated in the laboratory toxicity studies However in several instances the ERA does not adequately consider the effects of grain size in interpreting the study results

The ERA states that the benthic community data indicated that five of the six stations with median tPCB concentrations above 5 mgkg had significant benthic community alteration (p D-98) Those same five stations had coarse-grained sediments (see Figures D4-6 and D4-7) The one fine-grained station with median tPCB concentrations greater than 5 mgkg (Station 8) had higher species richness and abundance than the coarse-grained stations and was not significantly different from the reference stations (see Figures D4-6 D4-7 and D4-15) Benthic invertebrates tend to be the least diverse and the least abundant in sand likely due to its instability (Ward 1992 Minshall 1984 Allan 1995) Thus even in the absence of PCBs the diversity and abundance of invertebrates would be expected to be lower at the coarse-grained stations In these circumstances it is at least equally likely that grain size rather than PCB concentration explains the spatial variations in benthic community structure As a result the statements throughout the ERA regarding the high level of confidence in the conclusion that benthic invertebrates in the Housatonic River experience unacceptable risks due to tPCBs (eg p 12-55) are not be supported Those statements should be revised to recognize the confounding impacts and uncertainty associated with grain size effects and to note that as a result the benthic community data do not provide conclusive evidence of tPCB effects on changes in community structure

Similar concerns apply to the bioassay test The reference stations used in the bioassay test (Al and A3) are coarse-grained (Figure D2-2) whereas the treatment stations showing the highest levels of response (Stations 7 8 and 8A) are fine-grained Statistical analyses and the weight of evidence evaluation are based on comparisons made between Housatonic River sediment stations and references regardless of grain size (Table D3-4 and Figure D4-15) The uncertainty associated with comparing the toxicity of fine-grained stations to coarse-grained reference treatments should be acknowledged

313 Use of Sediment Quality Values and Toxicity Identification Evaluation in the Weight-of-Evidence

The ERA also relies on published Sediment Quality Values (SQVs) to support a sediment toxicity threshold value of 3 to 5 mgkg (pp 3-71 D-98) SQVs are generic in nature and therefore are primarily appropriate in screening-level ERAs when no site-specific data are available (see eg Long et al 1995) Given the availability of substantial site-specific data the generic SQVs should not be used at all or at a minimum given very low weight and the references to them should be removed from the conclusions

The ERA also gives moderate weight to the results of the Toxicity Identification Evaluation (TIE) (Table D4-5) The ERA concludes from this Phase I TIE that PCBs may be the main causal agent in the toxicity studies (p D-78) However the TIE was not a definitive study and was not designed to provide an independent evaluation of effects and the results of the TIE are inconclusive showing only that non-polar organic chemicals were likely responsible for the observed toxicity As a result while the results of the TIE provide some evidence as to the degree to which observed effects can be linked to PCBs rather than other COPCs the TIE study should be removed as a separate line of evidence

314 Need to Acknowledge Additional Uncertainties There are a number of uncertainties associated with the benthic invertebrate studies Some of these are acknowledged in the text (pp D-95 through D-98) but other critical uncertainties are not The text should be revised to acknowledge the following uncertainties

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Lack of concordance between benthic community and sediment toxicity study results At the four stations for which there are both sediment toxicity test data and benthic community data those results are contradictory The sediment toxicity tests show a toxic response for most endpoints (especially at Stations 7 and 8) whereas the benthic community analyses do not (see Figure D4-15) GE recommends that the ERA be revised to discuss this point in the uncertainty section and also to carry this through to the conclusions in terms of the ability to extrapolate the potential for adverse effects to downstream locations

Inconsistent patterns oftPCB concentrations in sediment and tissues The ERA likewise does not discuss the fact that the median tPCB concentrations in sediments and those in tissue are not consistent (eg elevated tPCB concentrations in sediments were not co-located with those in tissue) (compare Figure 33-3 on p 3-18 with Figure 33-6 on p 3-22) These inconsistencies raise questions regarding the reliability of using median sediment concentrations as a measure of exposure for benthic invertebrates They also limit the usefulness of the biota sediment accumulation factors (BSAFs) which range from 08 to 61 (p D-32) in predicting tissue levels from sediment concentrations These inconsistencies should be acknowledged in the discussion of tissue chemistry (Section 335 pp 3-21 and 3-23) and the implications relative to estimating exposure should be addressed in the uncertainty section

Calculation of LC$o and ICso values The toxicity test endpoints presented in Tables D4-1 through D4-3 based on statistical analyses have a number of significant uncertainties Specifically uncertainties are associated with the results in which (a) the chi-square value exceeds the critical value in the derivation of LCjos and LC2os (20 out of 54 endpoints) (b) visual observations rather than the probit analyses were used because the model did not converge (2 out of 54 endpoints) and (c) there was an interrupted dose-response (9 of 54 endpoints) These difficulties with the statistical analyses are indicative of inconsistencies in the dose-response relationships that result in uncertainty surrounding the threshold values These uncertainties should be addressed (Tables D4-1 - D4-3) In addition no explanation is provided for why the highest dose (772 mgkg) for H azteca 48-h survival is excluded from the effects threshold analysis (Table D4-1) Additional information should be included regarding its exclusion or the analyses should be redone using the results of this treatment

Use of single samples to characterize sediment in used in bioassays A discussion of the uncertainty associated with determining exposure values of sediment composites used in toxicity testing based on a single chemistry sample should be provided (p D-17) Alternatively if multiple samples were used to evaluate potential heterogeneity in these composites to confirm that sediment was completely mixed then those data should be provided

315 Need for Additional Clarification and Information This section describes a number of issues for which the next draft of the ERA should provide clarification or additional data or analyses

Tissue effects thresholds from the literature The ERA states that the literature review was focused on Aroclor 1260 and 1254 (p 3-14) It should be revised to state that no effects thresholds were found based on studies with Aroclor 1260 and that only studies of tPCBs Aroclor 1254 and Clophen A50 were used to derive these thresholds The figures summarizing the literature effects thresholds should also be revised to indicate which study is associated with the effects reported (eg in Figure 44-13)

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and to indicate that studies with Clophen A50 are included in the summary In addition congenershyspecific studies should be removed from the literature review (Table D3-5 and Attachment DI) as they are not appropriate surrogates for tPCB toxicity

Multi-dimensional scaling analysis The results of the multi-dimensional scaling (MDS) statistical analyses used to develop Figures D3-15 through D3-17 should be presented This will provide important information regarding the relative contribution of different factors in this multivariate analysis

Derivation of MATCs The ERA does not explain explicitly how the sediment MATC of 3 mgkg tPCB (p 3-72) used to assess the extent of risks downstream from the PSA was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should specifically document the derivation of the MATC value used

32 Amphibians In the assessment of amphibians the ERA derives toxicity thresholds (MATCs) of 1 mgkg in both tissue (based on the literature) and sediments (based on the results of EPAs wood frog study) As discussed below GE believes that neither of these thresholds is supported by the underlying studies and that they should be higher Moreover in evaluating the results of the wood frog study the ERA does not consider certain endpoints (metamorphosis and mortality) that have clear ecological relevance these endpoints should be included in the evaluation In addition as further discussed in these comments we urge EPA to (a) give lower weight to the results of the leopard frog study and explicitly recognize its use of external reference frogs (b) recognize additional specified uncertainties in the amphibian assessment (c) clarify or present additional data or analyses on certain issues (d) modify the extrapolation to reaches downstream of Woods Pond and (e) correct an error in the text1

321 Lack of Literature Support for a Toxicity Threshold of 1 mgkg tPCBs in Tissue The ERA specifies a toxicity threshold of 1 mgkg in tissue based on a review of the literature (pp 4shy75 E-96) The studies and results used in this review are summarized in Figures 44-13 and E3-37 However the two tPCB LOAELs (called LOELs in these figures) below 1 mgkg shown in these figures are not supported by the underlying study (Gutleb et al 2000) One of these effects levels for time to metamorphosis for the African clawed frog is based on exposure to PCB 126 although tissue chemistry was analyzed as tPCBs Comparing tPCB concentrations to effects levels from a study in which larvae were exposed to PCB 126 would substantially overstate tPCB toxicity and hence this effect level should not be used to evaluate potential tPCB effects The second LOAEL for the European common frog is 024 mgkg tPCBs (wet weight2) in tissue (based on exposure to Clophen A50) However at that concentration there was no adverse effect body weight in the exposed frogs was higher not lower than in the control frogs In fact there was no significant effect on body weight at the highest tissue concentration used in this study (112 mgkg tPCBs wet weight) Hence the latter

1 As noted in Section 1 EPA has also agreed to include the frog study sponsored by GE (Resetarits 2002) in the next draft of the ERA In addition GE has recently completed a study of leopard frog egg masses in the PSA and is providing a report on that study to EPA (ARCADIS 2003) That study should likewise be included in the next draft of the ERA

2 As converted from lipid weight in Attachment E2

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value should be reported as an unbounded NOAEL for that endpoint and the value reported as a LOAEL (024 mgkg) should be removed from these figures

Additional concerns associated with the summary of the literature effects are related to the interpretation of the frequency of occurrence of adverse effects (p 4-56 and E-81) First three LOAELs are cited for mortality based on a single experiment (Savage et al 2002) (Figure 4431 p 4shy57 and E3-37 p 60) By definition a LOAEL is the lowest concentration in an experiment for which there is a statistically significant difference relative to the control therefore only the LOAEL at approximately 6 mgkg from this study should be included in this figure When the erroneous LOAEL (Gutleb et al 2000) and the redundant LOAELs (Savage et al 2002) are removed the frequency of adverse effect analysis indicates that 4 out of 12 endpoints (for tPCBs) or 33 demonstrate adverse effects at concentrations greater than 1 mgkg and that in fact no adverse effects are observed below 6 mgkg

In addition the meaning of this frequency of adverse effects is not clear because there are substantive differences between the nature of effects observed For example the endpoints of reduced activity or swimming speed may or may not have the same severity of impact to an individual as increased mortality This distinction is lost in a simple evaluation of frequency of effects between different endpoints in various literature studies

Based on the above discussion the statement that [tjhere were six instances of adverse effects occurring between 1 and 10 mgkg (pp 4-56 and E-81) should be revised For tPCBs there are only three LOAELs (ie incidence of adverse effects) between 1 and 10 mgkg and all them are at or above 6 mgkg The text should be revised accordingly If the interpretation of these studies based on the frequency of adverse effects is retained that text should also be revised and uncertainties associated with direct comparisons of the different kinds of effects included in this analysis should be acknowledged

322 Lack of Support for a Sediment Toxicity Threshold of 1 mgkg Based on Wood Frog Study

The sediment toxicity threshold of 1 mgkg is apparently based primarily on an analysis of the results of EPAs wood frog study However the description of the results of that study states that [e]cologically significant adverse effects in late stage juvenile wood frogs occurred in the sediment tPCB concentration range of 10 to 60 mgkg although responses of lesser magnitude yet statistically significant were observed at 5 mgkg tPCB and lower (p 4-60) The latter statement (which may be the basis for the threshold) is apparently derived from the wood frog NOAELs and LOAELs presented in Table E4-2 However there are several problems or inconsistencies in the derivation of site-specific NOAELs and LOAELs presented in Table E4-2

bull In several instances the NOAELs and LOAELs do not coincide with sediment concentrations that are associated with the effects data For example the spatially weighted mean tPCB value of 136 mgkg is presented as either a NOAEL or LOAEL for all four endpoints in Table E4-2 However it appears that this value is associated with a vernal pool (46-VP-4 Table E2-8) that has no effects data associated with it (see Tables E3-5- E3-6 and E 310 - E3-11)

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bull It appears that the reference WML-1 has been excluded from the calculation of NOAELs and LOAELs for Phase III metamorphs because of zero response at this concentration(Table E4-2) This exclusion is not warranted While the text refers to the tissue tPCB concentration for reference location WML-1 in the Phase III of the wood frog study as anomalous (eg p 4-52) no problems with data quality are reported that would indicate that the organism did not in fact have a tissue burden of 44 mgkg tPCBs As a result responses associated with this exposure level should be considered to represent part of the range of effects and all analyses of exposure and effect should include this reference site Statistical comparisons with a zero value are commonly made using a value marginally greater than zero (eg 000001)

bull Concentration-response relationships for each endpoint were evaluated using both (1) the most synoptic chemistry value paired with each toxicity endpoint (also referred to as vernal pool sediment) and (2) a combined data set used to generate a spatially weighted surface average (pp 4shy16 mdash 4-17) Given the variability in sediment concentrations the samples used in the laboratory toxicity study should not be assumed to be equivalent to the surface weighted average The synoptic (ie vernal pool) data reflect the actual tPCB concentrations measured in sediments used in the laboratory exposures and should thus should be used for analyses of the Phase I wood frog study which was conducted in the laboratory The surface weighted averages should be used for the analysis of Phase II and Phase III studies in which larvae and metamorphs were exposed in the field as they encompass the range of concentrations to which the growing larvae and metamorphs might have been exposed to The NOAELs LOAELs and point estimates for effects concentrations (eg LC50 and LC20) (Table E4-2) should be revised accordingly

bull Table E4-2 states that the reference site had no malformed specimens (Phase II metamorphs percent malformed) In fact Table E3-11 indicates that reference site WML-3 had 29 malformations

Moreover the toxicity threshold for wood frogs was derived based only on endpoints that showed effects The ERA states that if no discern[i]ble differences in effect levels across treatments were observed (ie inadequate range in response variable) the effects endpoint was not considered in the detailed statistical evaluation (p E-90) As a result as discussed in the next section the lack of PCB-related effects for key endpoints (ie mortality and metamorphosis) were not considered in the derivation of the effects threshold Consideration of the results for those omitted endpoints shows further that the sediment MATC of 1 mgkg is too low

We also note that although Appendix E presents tissue-based HQs for leopard frogs and wood frogs (pp E-96 - E-98) Section 12 of the ERA presents only sediment-based HQs (Figures 122-1 and p 12shy7) Tissue concentrations provide a more direct measure of exposure than do sediment concentrations and hence the tissue-based rather than sediment-based HQs should be used in Section 12

323 Need to Consider Additional Relevant Endpoints in Wood Frog Study As noted above in evaluating the results of the wood frog study two endpoints with clear ecological relevance ~ metamorphosis and mortality -- were screened out of the formal concentration-response modeling due to a lack of discern[i]ble differences in effect levels across treatments (p E-90) However these two endpoints integrate other effects (ie the most serious effect of malformations would be reduced metamorphosis and increased mortality) and should be carried through the

concentration-response evaluation If no concentration-response curve can be derived because there were no effects then the highest dose should be treated as a NOAEL for these endpoints the LC50

should be expressed as gt highest dose and both mortality and metamorphosis should be considered subsequently as part of the lines-of-evidence evaluation

324 Evaluation of the Leopard Frog Study EPAs leopard frog study receives the same overall weight (moderatehigh) as its wood frog study in the weight-of evidence-evaluation (Table 45-4 p 4-69) Considering the significant problems with the leopard frog study as detailed in GEs comments on this study (BBL Sciences et al 2003a) it should be accorded a low weight

Moreover the text does not consistently acknowledge that reference frogs for the leopard frog study were obtained from a biological supply company For readers unfamiliar with the underlying study this could lead to misinterpretations of the results presented The text should be modified to clearly represent this aspect of the leopard frog study as well as additional qualifications as follows

bull The first time the study design of the leopard frog study is presented it should be clearly stated that no frogs or eggslarvae were found in the reference areas (p 4-13)

bull The text that describes comparisons between both the toxicity studies and the community evaluations and appropriately matched field references (p 4-27) should be revised to indicate that for the leopard frog study the field reference was limited to sediment not frogs collected from a reference pond

bull Although the text states that reference ponds were surveyed for eggs and larvae it does not indicate that in addition to no eggs or larvae being found at four of nine contaminated sites none were found at the reference sites (p 4-35)

bull Similarly the summary of female leopard frog reproductive fitness identifies all of the Housatonic River sites that were not gravid (did not have eggs mature enough for successful fertilization) (p 4shy30) It should also indicate that R2 (external reference) did not have any successful fertilization

325 Need to Acknowledge Additional Uncertainties While the ERA acknowledges some uncertainties associated with the amphibian studies (pp 4-70 4shy73 E-108-110) other critical uncertainties are not acknowledged For example there are uncertainties associated with the concentration-response analysis (eg ECsos ECaos) based on the poor fit of the data in the probit analysis Contrary to the statement that most endpoints followed a fairly smooth concentration-response (text box p 4-60) Table E4-2 indicates that only one of 11 of the ECsos presented (ie Phase III metamorph percent malformed based on comparisons with the lowest vernal pool sediment tPCB concentration) appears to be appropriately described by the probit analysis The other ECsos were described as (a) outside data range confidence limits increase (111) (b) probit model had poor fit to data confidence limits increase (111) (c) calculated with linear interpolation no confidence limits can be calculated (311) and (d) based on visual inspection of data (511) These uncertainties should be recognized

326 Need for Additional Information There are a number of issues on which we urge EPA to provide additional information in the next draft of the ERA

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Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

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Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

considerable conservatism is contributed to the HQs by both the exposure assumptions and the effects metrics If these sources of conservatism are not corrected through alternate assumptions then the conservatism that they contribute should be explicitly acknowledged in the ERA Some of the general sources of conservatism are discussed below while specific comments on the individual receptors are provided in Section 3

2321 Exposure assumptions For all receptors the ERA states that because food intake rates are poorly characterized in the literature it is necessary to model food intake rates based on allometric equations provided in the Wildlife Exposure Factors Handbook (EPA 1993) (eg pp 7-16 8-17 9-13 10-13 11-13) In fact however the EPA (1993) handbook provides measured species-specific food intake rates for all receptor species evaluated in the ERA except tree swallows river otters American bitterns and small-footed myotis According to EPA (1993) measured species-specific values are preferred over modeling intake rates based on allometric equations (p 3-1) GE recommends the use of the species-specific food intake rates reported in the Wildlife Exposure Factors Handbook (EPA 1993) Where that is not or cannot be done the uncertainty associated with using generic allometric equations and input variables that are not species-specific should be discussed and accounted for in the weight-ofshyevidence evaluations

In addition the use of point estimates to characterize the concentrations of COPCs in food and proportion of food derived from the site appears to be inconsistent with the ERAs own criteria for the use of distributions and point estimates The ERA states that point estimates [are used] for minor variables or variables with low coefficients of variation (p 6-17 H-7) Although coefficients of variation are not presented in the ERA and the sensitivity analyses exclude variables characterized with point estimates concentrations of COPCs in food and proportion of diet derived from the site cannot be described as minor because they directly control the magnitude of estimated dose Use of point estimates for these variables prevents uncertainty from being propagated through the probability bounds of the exposure model (p 12-10) and restricts the applicability of the results to those individuals (if any) that only derive their food from the PSA and that always consume food containing the highest concentrations of COPCs In order to align practices applied in the ERA with the stated methodologies GE recommends representation of these variables with appropriate statistical distributions

2322 Effects metrics Many aspects of the effects metrics also contribute to conservatism and uncertainty in the HQs As described in Section 3 these limitations include (for various receptors) the absence of clear documentation of the practices employed in development of the effects metrics lack of support by the underlying studies or failure to reflect the full body of toxicological literature andor lack of acknowledgment of important sources of uncertainty GE recommends revision of the effects metrics in the ERA as discussed in Section 3

The ERA (eg p 6-20) also states that in all cases effects metrics were consistent with the metrics used in the exposure analysis However the ways in which they are consistent are not defined While the effects metrics and exposure analyses are consistent with respect to units (eg mgkg-day) in many cases they are inconsistent with respect to species exposure duration and dosing regime For example an effect metric based on a domesticated species (ie white leghorn chickens) cannot be

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considered consistent with exposure metrics for wild avian receptors GE recommends revising the above statement so that it specifies the ways in which effects metrics are consistent with exposure metrics GE also recommends that the weight-of-evidence evaluations be modified to account for inconsistencies with respect to species exposure duration and dosing regime

24 Exclusion of Data Quality from Weight-of-Evidence Evaluations Based on Menzie et als (1996) quantitative weight-of-evidence approach data quality is one of the most important attributes in determining the scientific defensibility of a measurement endpoint Nonetheless the ERA does not include data quality as an attribute in the weight-of-evidence evaluations Instead the ERA asserts that all studies used in the ERA (except those conducted by GE contractors) have adequate data quality (p 2-70) However the criteria for determining the adequacy of data quality are not defined the process and outcome of a data quality evaluation are not provided and the underlying studies and data are not provided Consequently it is not possible to verify the validity of the assumption that all data have adequate quality In addition this approach implies that data quality for all measurement endpoints based on EPAs studies are equal In fact data quality varies considerably among the underlying studies For example errors and inconsistencies in the databases and analyses presented in underlying studies were identified in comments that GE has previously submitted to EPA The exclusion of data quality from the weight-of-evidence evaluation prevents EPA from accounting for those differences hi data quality

For these reasons GE urges EPA to modify the ERA so that it (a) specifies all necessary information to allow an independent evaluation of data quality for each measurement endpoint (b) includes the attribute of data quality in the weight-of-evidence evaluations and (c) acknowledges any data quality limitations

25 Discussion of Evidence Regarding Abundant Populations Section 12322 of the ERA lists a number of factors that it asserts indicate that studies showing an abundant population of a given receptor at the site do not demonstrate a lack of adverse effects on that population (pp 12-48 through 12-50) The ERA claims that (a) removal of predators compensates for direct effects of contaminants (b) immigration compensates for direct effects of contaminants (c) populations exposed to COPCs may be more vulnerable to other stressors in the future due to chemical adaptation andor immune system effects The application of these theories to a specific site such as the PSA is speculative and unsupported by the underlying studies None of the studies discussed in the ERA was designed to evaluate these types of effects GE believes that this entire discussion should be deleted from the ERA as speculative and unsupported by the data

26 Extrapolation across Species and Reaches The ERA extrapolates findings for risks posed to individual receptors within the PSA to other species and to areas outside the PSA There are several limitations associated with these practices as discussed below

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261 Risk Comparisons across Species The ERA qualitatively extrapolates predicted risks for each receptor to other species within the same feeding guild based on factors that influence exposure to COPCs (eg diet foraging range body weight) There are a number of problems with this approach First in the absence of data on the other species these extrapolations are not supported by any actual evidence Second these extrapolations of risk do not recognize that risk is a function not only of exposure but also of toxicological sensitivity By making the extrapolations based on factors that relate solely to exposure the ERA implies that all species within a feeding guild are equally sensitive to the toxicological effects of the COPCs However as demonstrated by Brunstrom and Lund (1988) toxicological sensitivity can vary by orders of magnitude across species even for species in the same feeding guild and taxonomic order (eg chickens and turkeys) Hence these analyses should not be referred to as comparisons of risk

The interspecies extrapolations also do not account for field data that either support or refute qualitative conclusions regarding relative risks For example data collected by the Massachusetts Division of Fisheries and Wildlife since 1980 on the productivity of great blue herons throughout Massachusetts show no differences in the numbers of young per nest for herons breeding within or beyond foraging distance of the PSA (MDFW 1979 1980 1981 1982 1983 1984 1985 1986ab 1987 1989 1991 1996) This finding does not support the ERAs qualitative finding that great blue herons face similar to higher risks than American bitterns which are predicted to have high risks (p 12-36)

GE recommends that extrapolations of risk estimates from receptors of interest to other species be omitted from the ERA because they are too uncertain to provide useful information If they are retained GE recommends that the comparisons be accurately characterized as comparisons of potential exposure rather than as comparisons of risk Regardless of how the extrapolations are presented however uncertainties should be explicitly reported including both the inability of the analysis to account for interspecies differences in toxicological sensitivity and cases where available field data contradict the extrapolated findings

262 Extrapolations to Downstream Reaches The field studies surveys and sampling program conducted for the ERA primarily focus on the PSA In an effort to apply the analyses across the entire study area the ERA extrapolates risks downstream of the PSA for seven receptors (benthic invertebrates amphibians warm water fish trout mink otter and bald eagles) For each of these groups the ERA identifies a maximum acceptable threshold concentration (MATC) for total PCBs (tPCBs) Each MATC is then compared to exposure concentrations for individual river and floodplain reaches downstream of Woods Pond to Long Island Sound Areas where exposure concentrations exceed the MATCs are interpreted as indicating potential risks

GE recommends several improvements in this approach (a) revision of the MATCs (b) improved spatial resolution of the overlap between predictions of risk to each receptor and the availability of suitable habitat for those receptors and (c) an explicit discussion of the uncertainties associated with these extrapolations In addition more complete documentation of the methodologies and assumptions employed would enhance the transparency of the analysis

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First several of the MATCs (eg for benthic invertebrates amphibians fish and bald eagles) are not supported by the site-specific studies or the scientific literature Specific concerns related to the basis for these MATCs are discussed below in Sections 311 (benthic invertebrates) 321 amp 322 (amphibians) 332 amp 333 (fish) and 3822 (bald eagles) GE recommends that these MATCs be revised

Second the applicability of the benchmark comparisons for each of the seven receptors should also be considered relative to the available habitat for such receptors in the downstream reaches For example although the MATC for amphibians was developed based on sediment tPCB concentrations in breeding ponds it was applied downstream of Woods Pond to soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data in the downstream reaches (p 12-15) Although such data may be lacking the ERA should make clear that the extrapolation applies only to sediment in potential floodplain ponds downstream of Woods Pond In addition risks to mink otters and bald eagles are evaluated for all reaches of the river with adequate data on exposure concentrations regardless of habitat Restricting the assessment of risks for these receptors to those reaches with suitable habitat would further improve the accuracy of these extrapolations

Third uncertainties in the extrapolations should be discussed and the results should be subjected to a separate weight-of-evidence evaluation

Finally the ERA does not provide enough information regarding the actual methodologies and assumptions used in the analysis of risks downstream of Woods Pond Transparency in this analysis is of paramount importance given the potential influence and use of these extrapolated risk results In particular the ERA should report the actual exposure concentrations used and whether they are spatially weighted averages arithmetic averages 95 upper confidence limits (UCLs) maxima etc In addition EPA should provide at least general information regarding the suitability of the downstream habitat for these receptors or where such information does not exist acknowledge that habitat has not been evaluated and could have a significant effect on any risks downstream of Woods Pond

27 Characterization of GEs Position In several places (pp 2-60 2-61) the ERA characterizes GEs position GE requests that such descriptions of GEs position be removed from the ERA GE will present its position in its comments during the public comment period andor to the Peer Review Panel

28 Non-PCB Constituents The ERA covers the Rest of River which is defined in the Consent Decree (Paragraph 6) as the Housatonic River and its sediments and floodplain areas downstream of the Confluence of the East and West Branches of the Housatonic River including backwaters except for ActualPotential Lawns to the extent that such areas are areas to which Waste Materials that originated at the GE Plant Area have migrated and which are being investigated or remediated pursuant to this Consent Decree (emphasis added) The Revised RCRA Permit contains a similar definition (Definition 19) limiting the Rest of River areas to areas to which releases of hazardous wastes andor hazardous constituents are migrating or have migrated from the GE Facility

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The ERA recognizes that the Rest of River includes areas of the Housatonic River and its sediments and floodplain (except ActualPotential Lawns) in which contaminants migrating from the GE facility are located (p 1-2) However it includes as COPCs a number of non-PCB constituents that are or may not be related to releases from the GE facility These include for various media numerous polycyclic aromatic hydrocarbons (PAHs) and other semi-volatile organic compounds (SVOCs) dioxins and furans several metals and (for fish) certain pesticides (Tables 24-2 through 24-5) There are multiple potential sources of these constituents in the Rest of River area not just releases from the GE facility

To avoid any confusion the ERA should make clear in its discussions of the COPCs (Sections 231 and 243) that while several COPCs other than PCBs have been selected for the ERA there are multiple potential sources of these constituents and hence there is no evidence demonstrating that the occurrence of these COPCs in the Rest of River area is necessarily derived from releases attributable to GE

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3 Specific Comments

31 Benthic Invertebrates In its assessment of benthic invertebrates the ERA derives toxicity thresholds (MATCs) of 3 mgkg tPCB in both tissue (based on the literature) and sediments (based on the results of toxicity and benthic community studies) GE believes that these thresholds should be reevaluated As discussed in this section GE urges EPA to make the following changes to the ERAs assessment of benthic invertebrates (a) use a different data set to calculate sediment-based toxicity thresholds (b) take adequate account of sediment grain size in interpreting the benthic community and toxicity test results (c) reduce the emphasis on Sediment Quality Values and the Toxicity Identification Evaluation (TIE) results (d) recognize a number of additional specified uncertainties and (e) clarify or provide additional information on certain issues

311 Concentration-Response Analysis to Derive Sediment Toxicity Thresholds The ERA concludes that the toxicity studies showed ecologically significant effects at sediment tPCB concentrations of 3 mgkg or higher (pp 3-71 D-98) the proposed MATC for sediment This proposed toxicity threshold is apparently based on LCso and ICso values from laboratory studies that were calculated based on the median values of multiple grab samples (p D-10) (some of which were collected independently of the laboratory bioassays) rather than based on measured concentrations of PCBs in sediments actually used in these bioassays The use of these unrelated data as a basis for establishing exposure levels in laboratory bioassays is of concern given that PCB concentrations in sediments of the Housatonic River can vary by orders of magnitude over very small spatial and temporal scales (pp D-26 to D-28) The rationale given for this method is that combining data from sampling events that are approximately (but not exactly) synoptic with the effects data more accurately portrays the COC concentrations at each station (p D-27) This approach may provide an indication of PCB concentrations in the vicinity of a station over time but it does not provide a better measure of PCB concentrations in the specific composites used in the bioassays than would a direct measure of PCBs in the sediments used in the bioassays For some stations concentrations measured directly from the composites are in fact substantially different than those derived from other collection efforts (Figures D3-1 through D3-5 Stations 7 and 8A) resulting in variability which likely substantially affects the exposure-response analyses and resulting LCsos and ICsoS Because of this variability it is important that effects levels for bioassay tests be calculated from the data that represent the concentrations to which these organisms were actually exposed

GE recommends that the ERA be revised to calculate the No Observed Adverse Effect Levels (NOAELs) Lowest Observed Adverse Effect Levels (LOAELs) and LCsoICso values for the laboratory bioassays (Tables D4-2 and D4-3) based on the synoptic values derived directly from the composite samples for the laboratory bioassays because these values best represent the exposures to the test organisms The LCao and IC20 values should also be revised in a similar manner as should the linear regression models (Table D4-4 Figure D4-5)

312 Effects of Grain Size on Study Interpretation Grain size is a significant variable that can impact both benthic community structure and the endpoints evaluated in the laboratory toxicity studies However in several instances the ERA does not adequately consider the effects of grain size in interpreting the study results

The ERA states that the benthic community data indicated that five of the six stations with median tPCB concentrations above 5 mgkg had significant benthic community alteration (p D-98) Those same five stations had coarse-grained sediments (see Figures D4-6 and D4-7) The one fine-grained station with median tPCB concentrations greater than 5 mgkg (Station 8) had higher species richness and abundance than the coarse-grained stations and was not significantly different from the reference stations (see Figures D4-6 D4-7 and D4-15) Benthic invertebrates tend to be the least diverse and the least abundant in sand likely due to its instability (Ward 1992 Minshall 1984 Allan 1995) Thus even in the absence of PCBs the diversity and abundance of invertebrates would be expected to be lower at the coarse-grained stations In these circumstances it is at least equally likely that grain size rather than PCB concentration explains the spatial variations in benthic community structure As a result the statements throughout the ERA regarding the high level of confidence in the conclusion that benthic invertebrates in the Housatonic River experience unacceptable risks due to tPCBs (eg p 12-55) are not be supported Those statements should be revised to recognize the confounding impacts and uncertainty associated with grain size effects and to note that as a result the benthic community data do not provide conclusive evidence of tPCB effects on changes in community structure

Similar concerns apply to the bioassay test The reference stations used in the bioassay test (Al and A3) are coarse-grained (Figure D2-2) whereas the treatment stations showing the highest levels of response (Stations 7 8 and 8A) are fine-grained Statistical analyses and the weight of evidence evaluation are based on comparisons made between Housatonic River sediment stations and references regardless of grain size (Table D3-4 and Figure D4-15) The uncertainty associated with comparing the toxicity of fine-grained stations to coarse-grained reference treatments should be acknowledged

313 Use of Sediment Quality Values and Toxicity Identification Evaluation in the Weight-of-Evidence

The ERA also relies on published Sediment Quality Values (SQVs) to support a sediment toxicity threshold value of 3 to 5 mgkg (pp 3-71 D-98) SQVs are generic in nature and therefore are primarily appropriate in screening-level ERAs when no site-specific data are available (see eg Long et al 1995) Given the availability of substantial site-specific data the generic SQVs should not be used at all or at a minimum given very low weight and the references to them should be removed from the conclusions

The ERA also gives moderate weight to the results of the Toxicity Identification Evaluation (TIE) (Table D4-5) The ERA concludes from this Phase I TIE that PCBs may be the main causal agent in the toxicity studies (p D-78) However the TIE was not a definitive study and was not designed to provide an independent evaluation of effects and the results of the TIE are inconclusive showing only that non-polar organic chemicals were likely responsible for the observed toxicity As a result while the results of the TIE provide some evidence as to the degree to which observed effects can be linked to PCBs rather than other COPCs the TIE study should be removed as a separate line of evidence

314 Need to Acknowledge Additional Uncertainties There are a number of uncertainties associated with the benthic invertebrate studies Some of these are acknowledged in the text (pp D-95 through D-98) but other critical uncertainties are not The text should be revised to acknowledge the following uncertainties

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Lack of concordance between benthic community and sediment toxicity study results At the four stations for which there are both sediment toxicity test data and benthic community data those results are contradictory The sediment toxicity tests show a toxic response for most endpoints (especially at Stations 7 and 8) whereas the benthic community analyses do not (see Figure D4-15) GE recommends that the ERA be revised to discuss this point in the uncertainty section and also to carry this through to the conclusions in terms of the ability to extrapolate the potential for adverse effects to downstream locations

Inconsistent patterns oftPCB concentrations in sediment and tissues The ERA likewise does not discuss the fact that the median tPCB concentrations in sediments and those in tissue are not consistent (eg elevated tPCB concentrations in sediments were not co-located with those in tissue) (compare Figure 33-3 on p 3-18 with Figure 33-6 on p 3-22) These inconsistencies raise questions regarding the reliability of using median sediment concentrations as a measure of exposure for benthic invertebrates They also limit the usefulness of the biota sediment accumulation factors (BSAFs) which range from 08 to 61 (p D-32) in predicting tissue levels from sediment concentrations These inconsistencies should be acknowledged in the discussion of tissue chemistry (Section 335 pp 3-21 and 3-23) and the implications relative to estimating exposure should be addressed in the uncertainty section

Calculation of LC$o and ICso values The toxicity test endpoints presented in Tables D4-1 through D4-3 based on statistical analyses have a number of significant uncertainties Specifically uncertainties are associated with the results in which (a) the chi-square value exceeds the critical value in the derivation of LCjos and LC2os (20 out of 54 endpoints) (b) visual observations rather than the probit analyses were used because the model did not converge (2 out of 54 endpoints) and (c) there was an interrupted dose-response (9 of 54 endpoints) These difficulties with the statistical analyses are indicative of inconsistencies in the dose-response relationships that result in uncertainty surrounding the threshold values These uncertainties should be addressed (Tables D4-1 - D4-3) In addition no explanation is provided for why the highest dose (772 mgkg) for H azteca 48-h survival is excluded from the effects threshold analysis (Table D4-1) Additional information should be included regarding its exclusion or the analyses should be redone using the results of this treatment

Use of single samples to characterize sediment in used in bioassays A discussion of the uncertainty associated with determining exposure values of sediment composites used in toxicity testing based on a single chemistry sample should be provided (p D-17) Alternatively if multiple samples were used to evaluate potential heterogeneity in these composites to confirm that sediment was completely mixed then those data should be provided

315 Need for Additional Clarification and Information This section describes a number of issues for which the next draft of the ERA should provide clarification or additional data or analyses

Tissue effects thresholds from the literature The ERA states that the literature review was focused on Aroclor 1260 and 1254 (p 3-14) It should be revised to state that no effects thresholds were found based on studies with Aroclor 1260 and that only studies of tPCBs Aroclor 1254 and Clophen A50 were used to derive these thresholds The figures summarizing the literature effects thresholds should also be revised to indicate which study is associated with the effects reported (eg in Figure 44-13)

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and to indicate that studies with Clophen A50 are included in the summary In addition congenershyspecific studies should be removed from the literature review (Table D3-5 and Attachment DI) as they are not appropriate surrogates for tPCB toxicity

Multi-dimensional scaling analysis The results of the multi-dimensional scaling (MDS) statistical analyses used to develop Figures D3-15 through D3-17 should be presented This will provide important information regarding the relative contribution of different factors in this multivariate analysis

Derivation of MATCs The ERA does not explain explicitly how the sediment MATC of 3 mgkg tPCB (p 3-72) used to assess the extent of risks downstream from the PSA was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should specifically document the derivation of the MATC value used

32 Amphibians In the assessment of amphibians the ERA derives toxicity thresholds (MATCs) of 1 mgkg in both tissue (based on the literature) and sediments (based on the results of EPAs wood frog study) As discussed below GE believes that neither of these thresholds is supported by the underlying studies and that they should be higher Moreover in evaluating the results of the wood frog study the ERA does not consider certain endpoints (metamorphosis and mortality) that have clear ecological relevance these endpoints should be included in the evaluation In addition as further discussed in these comments we urge EPA to (a) give lower weight to the results of the leopard frog study and explicitly recognize its use of external reference frogs (b) recognize additional specified uncertainties in the amphibian assessment (c) clarify or present additional data or analyses on certain issues (d) modify the extrapolation to reaches downstream of Woods Pond and (e) correct an error in the text1

321 Lack of Literature Support for a Toxicity Threshold of 1 mgkg tPCBs in Tissue The ERA specifies a toxicity threshold of 1 mgkg in tissue based on a review of the literature (pp 4shy75 E-96) The studies and results used in this review are summarized in Figures 44-13 and E3-37 However the two tPCB LOAELs (called LOELs in these figures) below 1 mgkg shown in these figures are not supported by the underlying study (Gutleb et al 2000) One of these effects levels for time to metamorphosis for the African clawed frog is based on exposure to PCB 126 although tissue chemistry was analyzed as tPCBs Comparing tPCB concentrations to effects levels from a study in which larvae were exposed to PCB 126 would substantially overstate tPCB toxicity and hence this effect level should not be used to evaluate potential tPCB effects The second LOAEL for the European common frog is 024 mgkg tPCBs (wet weight2) in tissue (based on exposure to Clophen A50) However at that concentration there was no adverse effect body weight in the exposed frogs was higher not lower than in the control frogs In fact there was no significant effect on body weight at the highest tissue concentration used in this study (112 mgkg tPCBs wet weight) Hence the latter

1 As noted in Section 1 EPA has also agreed to include the frog study sponsored by GE (Resetarits 2002) in the next draft of the ERA In addition GE has recently completed a study of leopard frog egg masses in the PSA and is providing a report on that study to EPA (ARCADIS 2003) That study should likewise be included in the next draft of the ERA

2 As converted from lipid weight in Attachment E2

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value should be reported as an unbounded NOAEL for that endpoint and the value reported as a LOAEL (024 mgkg) should be removed from these figures

Additional concerns associated with the summary of the literature effects are related to the interpretation of the frequency of occurrence of adverse effects (p 4-56 and E-81) First three LOAELs are cited for mortality based on a single experiment (Savage et al 2002) (Figure 4431 p 4shy57 and E3-37 p 60) By definition a LOAEL is the lowest concentration in an experiment for which there is a statistically significant difference relative to the control therefore only the LOAEL at approximately 6 mgkg from this study should be included in this figure When the erroneous LOAEL (Gutleb et al 2000) and the redundant LOAELs (Savage et al 2002) are removed the frequency of adverse effect analysis indicates that 4 out of 12 endpoints (for tPCBs) or 33 demonstrate adverse effects at concentrations greater than 1 mgkg and that in fact no adverse effects are observed below 6 mgkg

In addition the meaning of this frequency of adverse effects is not clear because there are substantive differences between the nature of effects observed For example the endpoints of reduced activity or swimming speed may or may not have the same severity of impact to an individual as increased mortality This distinction is lost in a simple evaluation of frequency of effects between different endpoints in various literature studies

Based on the above discussion the statement that [tjhere were six instances of adverse effects occurring between 1 and 10 mgkg (pp 4-56 and E-81) should be revised For tPCBs there are only three LOAELs (ie incidence of adverse effects) between 1 and 10 mgkg and all them are at or above 6 mgkg The text should be revised accordingly If the interpretation of these studies based on the frequency of adverse effects is retained that text should also be revised and uncertainties associated with direct comparisons of the different kinds of effects included in this analysis should be acknowledged

322 Lack of Support for a Sediment Toxicity Threshold of 1 mgkg Based on Wood Frog Study

The sediment toxicity threshold of 1 mgkg is apparently based primarily on an analysis of the results of EPAs wood frog study However the description of the results of that study states that [e]cologically significant adverse effects in late stage juvenile wood frogs occurred in the sediment tPCB concentration range of 10 to 60 mgkg although responses of lesser magnitude yet statistically significant were observed at 5 mgkg tPCB and lower (p 4-60) The latter statement (which may be the basis for the threshold) is apparently derived from the wood frog NOAELs and LOAELs presented in Table E4-2 However there are several problems or inconsistencies in the derivation of site-specific NOAELs and LOAELs presented in Table E4-2

bull In several instances the NOAELs and LOAELs do not coincide with sediment concentrations that are associated with the effects data For example the spatially weighted mean tPCB value of 136 mgkg is presented as either a NOAEL or LOAEL for all four endpoints in Table E4-2 However it appears that this value is associated with a vernal pool (46-VP-4 Table E2-8) that has no effects data associated with it (see Tables E3-5- E3-6 and E 310 - E3-11)

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bull It appears that the reference WML-1 has been excluded from the calculation of NOAELs and LOAELs for Phase III metamorphs because of zero response at this concentration(Table E4-2) This exclusion is not warranted While the text refers to the tissue tPCB concentration for reference location WML-1 in the Phase III of the wood frog study as anomalous (eg p 4-52) no problems with data quality are reported that would indicate that the organism did not in fact have a tissue burden of 44 mgkg tPCBs As a result responses associated with this exposure level should be considered to represent part of the range of effects and all analyses of exposure and effect should include this reference site Statistical comparisons with a zero value are commonly made using a value marginally greater than zero (eg 000001)

bull Concentration-response relationships for each endpoint were evaluated using both (1) the most synoptic chemistry value paired with each toxicity endpoint (also referred to as vernal pool sediment) and (2) a combined data set used to generate a spatially weighted surface average (pp 4shy16 mdash 4-17) Given the variability in sediment concentrations the samples used in the laboratory toxicity study should not be assumed to be equivalent to the surface weighted average The synoptic (ie vernal pool) data reflect the actual tPCB concentrations measured in sediments used in the laboratory exposures and should thus should be used for analyses of the Phase I wood frog study which was conducted in the laboratory The surface weighted averages should be used for the analysis of Phase II and Phase III studies in which larvae and metamorphs were exposed in the field as they encompass the range of concentrations to which the growing larvae and metamorphs might have been exposed to The NOAELs LOAELs and point estimates for effects concentrations (eg LC50 and LC20) (Table E4-2) should be revised accordingly

bull Table E4-2 states that the reference site had no malformed specimens (Phase II metamorphs percent malformed) In fact Table E3-11 indicates that reference site WML-3 had 29 malformations

Moreover the toxicity threshold for wood frogs was derived based only on endpoints that showed effects The ERA states that if no discern[i]ble differences in effect levels across treatments were observed (ie inadequate range in response variable) the effects endpoint was not considered in the detailed statistical evaluation (p E-90) As a result as discussed in the next section the lack of PCB-related effects for key endpoints (ie mortality and metamorphosis) were not considered in the derivation of the effects threshold Consideration of the results for those omitted endpoints shows further that the sediment MATC of 1 mgkg is too low

We also note that although Appendix E presents tissue-based HQs for leopard frogs and wood frogs (pp E-96 - E-98) Section 12 of the ERA presents only sediment-based HQs (Figures 122-1 and p 12shy7) Tissue concentrations provide a more direct measure of exposure than do sediment concentrations and hence the tissue-based rather than sediment-based HQs should be used in Section 12

323 Need to Consider Additional Relevant Endpoints in Wood Frog Study As noted above in evaluating the results of the wood frog study two endpoints with clear ecological relevance ~ metamorphosis and mortality -- were screened out of the formal concentration-response modeling due to a lack of discern[i]ble differences in effect levels across treatments (p E-90) However these two endpoints integrate other effects (ie the most serious effect of malformations would be reduced metamorphosis and increased mortality) and should be carried through the

concentration-response evaluation If no concentration-response curve can be derived because there were no effects then the highest dose should be treated as a NOAEL for these endpoints the LC50

should be expressed as gt highest dose and both mortality and metamorphosis should be considered subsequently as part of the lines-of-evidence evaluation

324 Evaluation of the Leopard Frog Study EPAs leopard frog study receives the same overall weight (moderatehigh) as its wood frog study in the weight-of evidence-evaluation (Table 45-4 p 4-69) Considering the significant problems with the leopard frog study as detailed in GEs comments on this study (BBL Sciences et al 2003a) it should be accorded a low weight

Moreover the text does not consistently acknowledge that reference frogs for the leopard frog study were obtained from a biological supply company For readers unfamiliar with the underlying study this could lead to misinterpretations of the results presented The text should be modified to clearly represent this aspect of the leopard frog study as well as additional qualifications as follows

bull The first time the study design of the leopard frog study is presented it should be clearly stated that no frogs or eggslarvae were found in the reference areas (p 4-13)

bull The text that describes comparisons between both the toxicity studies and the community evaluations and appropriately matched field references (p 4-27) should be revised to indicate that for the leopard frog study the field reference was limited to sediment not frogs collected from a reference pond

bull Although the text states that reference ponds were surveyed for eggs and larvae it does not indicate that in addition to no eggs or larvae being found at four of nine contaminated sites none were found at the reference sites (p 4-35)

bull Similarly the summary of female leopard frog reproductive fitness identifies all of the Housatonic River sites that were not gravid (did not have eggs mature enough for successful fertilization) (p 4shy30) It should also indicate that R2 (external reference) did not have any successful fertilization

325 Need to Acknowledge Additional Uncertainties While the ERA acknowledges some uncertainties associated with the amphibian studies (pp 4-70 4shy73 E-108-110) other critical uncertainties are not acknowledged For example there are uncertainties associated with the concentration-response analysis (eg ECsos ECaos) based on the poor fit of the data in the probit analysis Contrary to the statement that most endpoints followed a fairly smooth concentration-response (text box p 4-60) Table E4-2 indicates that only one of 11 of the ECsos presented (ie Phase III metamorph percent malformed based on comparisons with the lowest vernal pool sediment tPCB concentration) appears to be appropriately described by the probit analysis The other ECsos were described as (a) outside data range confidence limits increase (111) (b) probit model had poor fit to data confidence limits increase (111) (c) calculated with linear interpolation no confidence limits can be calculated (311) and (d) based on visual inspection of data (511) These uncertainties should be recognized

326 Need for Additional Information There are a number of issues on which we urge EPA to provide additional information in the next draft of the ERA

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Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

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Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

considered consistent with exposure metrics for wild avian receptors GE recommends revising the above statement so that it specifies the ways in which effects metrics are consistent with exposure metrics GE also recommends that the weight-of-evidence evaluations be modified to account for inconsistencies with respect to species exposure duration and dosing regime

24 Exclusion of Data Quality from Weight-of-Evidence Evaluations Based on Menzie et als (1996) quantitative weight-of-evidence approach data quality is one of the most important attributes in determining the scientific defensibility of a measurement endpoint Nonetheless the ERA does not include data quality as an attribute in the weight-of-evidence evaluations Instead the ERA asserts that all studies used in the ERA (except those conducted by GE contractors) have adequate data quality (p 2-70) However the criteria for determining the adequacy of data quality are not defined the process and outcome of a data quality evaluation are not provided and the underlying studies and data are not provided Consequently it is not possible to verify the validity of the assumption that all data have adequate quality In addition this approach implies that data quality for all measurement endpoints based on EPAs studies are equal In fact data quality varies considerably among the underlying studies For example errors and inconsistencies in the databases and analyses presented in underlying studies were identified in comments that GE has previously submitted to EPA The exclusion of data quality from the weight-of-evidence evaluation prevents EPA from accounting for those differences hi data quality

For these reasons GE urges EPA to modify the ERA so that it (a) specifies all necessary information to allow an independent evaluation of data quality for each measurement endpoint (b) includes the attribute of data quality in the weight-of-evidence evaluations and (c) acknowledges any data quality limitations

25 Discussion of Evidence Regarding Abundant Populations Section 12322 of the ERA lists a number of factors that it asserts indicate that studies showing an abundant population of a given receptor at the site do not demonstrate a lack of adverse effects on that population (pp 12-48 through 12-50) The ERA claims that (a) removal of predators compensates for direct effects of contaminants (b) immigration compensates for direct effects of contaminants (c) populations exposed to COPCs may be more vulnerable to other stressors in the future due to chemical adaptation andor immune system effects The application of these theories to a specific site such as the PSA is speculative and unsupported by the underlying studies None of the studies discussed in the ERA was designed to evaluate these types of effects GE believes that this entire discussion should be deleted from the ERA as speculative and unsupported by the data

26 Extrapolation across Species and Reaches The ERA extrapolates findings for risks posed to individual receptors within the PSA to other species and to areas outside the PSA There are several limitations associated with these practices as discussed below

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261 Risk Comparisons across Species The ERA qualitatively extrapolates predicted risks for each receptor to other species within the same feeding guild based on factors that influence exposure to COPCs (eg diet foraging range body weight) There are a number of problems with this approach First in the absence of data on the other species these extrapolations are not supported by any actual evidence Second these extrapolations of risk do not recognize that risk is a function not only of exposure but also of toxicological sensitivity By making the extrapolations based on factors that relate solely to exposure the ERA implies that all species within a feeding guild are equally sensitive to the toxicological effects of the COPCs However as demonstrated by Brunstrom and Lund (1988) toxicological sensitivity can vary by orders of magnitude across species even for species in the same feeding guild and taxonomic order (eg chickens and turkeys) Hence these analyses should not be referred to as comparisons of risk

The interspecies extrapolations also do not account for field data that either support or refute qualitative conclusions regarding relative risks For example data collected by the Massachusetts Division of Fisheries and Wildlife since 1980 on the productivity of great blue herons throughout Massachusetts show no differences in the numbers of young per nest for herons breeding within or beyond foraging distance of the PSA (MDFW 1979 1980 1981 1982 1983 1984 1985 1986ab 1987 1989 1991 1996) This finding does not support the ERAs qualitative finding that great blue herons face similar to higher risks than American bitterns which are predicted to have high risks (p 12-36)

GE recommends that extrapolations of risk estimates from receptors of interest to other species be omitted from the ERA because they are too uncertain to provide useful information If they are retained GE recommends that the comparisons be accurately characterized as comparisons of potential exposure rather than as comparisons of risk Regardless of how the extrapolations are presented however uncertainties should be explicitly reported including both the inability of the analysis to account for interspecies differences in toxicological sensitivity and cases where available field data contradict the extrapolated findings

262 Extrapolations to Downstream Reaches The field studies surveys and sampling program conducted for the ERA primarily focus on the PSA In an effort to apply the analyses across the entire study area the ERA extrapolates risks downstream of the PSA for seven receptors (benthic invertebrates amphibians warm water fish trout mink otter and bald eagles) For each of these groups the ERA identifies a maximum acceptable threshold concentration (MATC) for total PCBs (tPCBs) Each MATC is then compared to exposure concentrations for individual river and floodplain reaches downstream of Woods Pond to Long Island Sound Areas where exposure concentrations exceed the MATCs are interpreted as indicating potential risks

GE recommends several improvements in this approach (a) revision of the MATCs (b) improved spatial resolution of the overlap between predictions of risk to each receptor and the availability of suitable habitat for those receptors and (c) an explicit discussion of the uncertainties associated with these extrapolations In addition more complete documentation of the methodologies and assumptions employed would enhance the transparency of the analysis

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First several of the MATCs (eg for benthic invertebrates amphibians fish and bald eagles) are not supported by the site-specific studies or the scientific literature Specific concerns related to the basis for these MATCs are discussed below in Sections 311 (benthic invertebrates) 321 amp 322 (amphibians) 332 amp 333 (fish) and 3822 (bald eagles) GE recommends that these MATCs be revised

Second the applicability of the benchmark comparisons for each of the seven receptors should also be considered relative to the available habitat for such receptors in the downstream reaches For example although the MATC for amphibians was developed based on sediment tPCB concentrations in breeding ponds it was applied downstream of Woods Pond to soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data in the downstream reaches (p 12-15) Although such data may be lacking the ERA should make clear that the extrapolation applies only to sediment in potential floodplain ponds downstream of Woods Pond In addition risks to mink otters and bald eagles are evaluated for all reaches of the river with adequate data on exposure concentrations regardless of habitat Restricting the assessment of risks for these receptors to those reaches with suitable habitat would further improve the accuracy of these extrapolations

Third uncertainties in the extrapolations should be discussed and the results should be subjected to a separate weight-of-evidence evaluation

Finally the ERA does not provide enough information regarding the actual methodologies and assumptions used in the analysis of risks downstream of Woods Pond Transparency in this analysis is of paramount importance given the potential influence and use of these extrapolated risk results In particular the ERA should report the actual exposure concentrations used and whether they are spatially weighted averages arithmetic averages 95 upper confidence limits (UCLs) maxima etc In addition EPA should provide at least general information regarding the suitability of the downstream habitat for these receptors or where such information does not exist acknowledge that habitat has not been evaluated and could have a significant effect on any risks downstream of Woods Pond

27 Characterization of GEs Position In several places (pp 2-60 2-61) the ERA characterizes GEs position GE requests that such descriptions of GEs position be removed from the ERA GE will present its position in its comments during the public comment period andor to the Peer Review Panel

28 Non-PCB Constituents The ERA covers the Rest of River which is defined in the Consent Decree (Paragraph 6) as the Housatonic River and its sediments and floodplain areas downstream of the Confluence of the East and West Branches of the Housatonic River including backwaters except for ActualPotential Lawns to the extent that such areas are areas to which Waste Materials that originated at the GE Plant Area have migrated and which are being investigated or remediated pursuant to this Consent Decree (emphasis added) The Revised RCRA Permit contains a similar definition (Definition 19) limiting the Rest of River areas to areas to which releases of hazardous wastes andor hazardous constituents are migrating or have migrated from the GE Facility

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The ERA recognizes that the Rest of River includes areas of the Housatonic River and its sediments and floodplain (except ActualPotential Lawns) in which contaminants migrating from the GE facility are located (p 1-2) However it includes as COPCs a number of non-PCB constituents that are or may not be related to releases from the GE facility These include for various media numerous polycyclic aromatic hydrocarbons (PAHs) and other semi-volatile organic compounds (SVOCs) dioxins and furans several metals and (for fish) certain pesticides (Tables 24-2 through 24-5) There are multiple potential sources of these constituents in the Rest of River area not just releases from the GE facility

To avoid any confusion the ERA should make clear in its discussions of the COPCs (Sections 231 and 243) that while several COPCs other than PCBs have been selected for the ERA there are multiple potential sources of these constituents and hence there is no evidence demonstrating that the occurrence of these COPCs in the Rest of River area is necessarily derived from releases attributable to GE

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3 Specific Comments

31 Benthic Invertebrates In its assessment of benthic invertebrates the ERA derives toxicity thresholds (MATCs) of 3 mgkg tPCB in both tissue (based on the literature) and sediments (based on the results of toxicity and benthic community studies) GE believes that these thresholds should be reevaluated As discussed in this section GE urges EPA to make the following changes to the ERAs assessment of benthic invertebrates (a) use a different data set to calculate sediment-based toxicity thresholds (b) take adequate account of sediment grain size in interpreting the benthic community and toxicity test results (c) reduce the emphasis on Sediment Quality Values and the Toxicity Identification Evaluation (TIE) results (d) recognize a number of additional specified uncertainties and (e) clarify or provide additional information on certain issues

311 Concentration-Response Analysis to Derive Sediment Toxicity Thresholds The ERA concludes that the toxicity studies showed ecologically significant effects at sediment tPCB concentrations of 3 mgkg or higher (pp 3-71 D-98) the proposed MATC for sediment This proposed toxicity threshold is apparently based on LCso and ICso values from laboratory studies that were calculated based on the median values of multiple grab samples (p D-10) (some of which were collected independently of the laboratory bioassays) rather than based on measured concentrations of PCBs in sediments actually used in these bioassays The use of these unrelated data as a basis for establishing exposure levels in laboratory bioassays is of concern given that PCB concentrations in sediments of the Housatonic River can vary by orders of magnitude over very small spatial and temporal scales (pp D-26 to D-28) The rationale given for this method is that combining data from sampling events that are approximately (but not exactly) synoptic with the effects data more accurately portrays the COC concentrations at each station (p D-27) This approach may provide an indication of PCB concentrations in the vicinity of a station over time but it does not provide a better measure of PCB concentrations in the specific composites used in the bioassays than would a direct measure of PCBs in the sediments used in the bioassays For some stations concentrations measured directly from the composites are in fact substantially different than those derived from other collection efforts (Figures D3-1 through D3-5 Stations 7 and 8A) resulting in variability which likely substantially affects the exposure-response analyses and resulting LCsos and ICsoS Because of this variability it is important that effects levels for bioassay tests be calculated from the data that represent the concentrations to which these organisms were actually exposed

GE recommends that the ERA be revised to calculate the No Observed Adverse Effect Levels (NOAELs) Lowest Observed Adverse Effect Levels (LOAELs) and LCsoICso values for the laboratory bioassays (Tables D4-2 and D4-3) based on the synoptic values derived directly from the composite samples for the laboratory bioassays because these values best represent the exposures to the test organisms The LCao and IC20 values should also be revised in a similar manner as should the linear regression models (Table D4-4 Figure D4-5)

312 Effects of Grain Size on Study Interpretation Grain size is a significant variable that can impact both benthic community structure and the endpoints evaluated in the laboratory toxicity studies However in several instances the ERA does not adequately consider the effects of grain size in interpreting the study results

The ERA states that the benthic community data indicated that five of the six stations with median tPCB concentrations above 5 mgkg had significant benthic community alteration (p D-98) Those same five stations had coarse-grained sediments (see Figures D4-6 and D4-7) The one fine-grained station with median tPCB concentrations greater than 5 mgkg (Station 8) had higher species richness and abundance than the coarse-grained stations and was not significantly different from the reference stations (see Figures D4-6 D4-7 and D4-15) Benthic invertebrates tend to be the least diverse and the least abundant in sand likely due to its instability (Ward 1992 Minshall 1984 Allan 1995) Thus even in the absence of PCBs the diversity and abundance of invertebrates would be expected to be lower at the coarse-grained stations In these circumstances it is at least equally likely that grain size rather than PCB concentration explains the spatial variations in benthic community structure As a result the statements throughout the ERA regarding the high level of confidence in the conclusion that benthic invertebrates in the Housatonic River experience unacceptable risks due to tPCBs (eg p 12-55) are not be supported Those statements should be revised to recognize the confounding impacts and uncertainty associated with grain size effects and to note that as a result the benthic community data do not provide conclusive evidence of tPCB effects on changes in community structure

Similar concerns apply to the bioassay test The reference stations used in the bioassay test (Al and A3) are coarse-grained (Figure D2-2) whereas the treatment stations showing the highest levels of response (Stations 7 8 and 8A) are fine-grained Statistical analyses and the weight of evidence evaluation are based on comparisons made between Housatonic River sediment stations and references regardless of grain size (Table D3-4 and Figure D4-15) The uncertainty associated with comparing the toxicity of fine-grained stations to coarse-grained reference treatments should be acknowledged

313 Use of Sediment Quality Values and Toxicity Identification Evaluation in the Weight-of-Evidence

The ERA also relies on published Sediment Quality Values (SQVs) to support a sediment toxicity threshold value of 3 to 5 mgkg (pp 3-71 D-98) SQVs are generic in nature and therefore are primarily appropriate in screening-level ERAs when no site-specific data are available (see eg Long et al 1995) Given the availability of substantial site-specific data the generic SQVs should not be used at all or at a minimum given very low weight and the references to them should be removed from the conclusions

The ERA also gives moderate weight to the results of the Toxicity Identification Evaluation (TIE) (Table D4-5) The ERA concludes from this Phase I TIE that PCBs may be the main causal agent in the toxicity studies (p D-78) However the TIE was not a definitive study and was not designed to provide an independent evaluation of effects and the results of the TIE are inconclusive showing only that non-polar organic chemicals were likely responsible for the observed toxicity As a result while the results of the TIE provide some evidence as to the degree to which observed effects can be linked to PCBs rather than other COPCs the TIE study should be removed as a separate line of evidence

314 Need to Acknowledge Additional Uncertainties There are a number of uncertainties associated with the benthic invertebrate studies Some of these are acknowledged in the text (pp D-95 through D-98) but other critical uncertainties are not The text should be revised to acknowledge the following uncertainties

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Lack of concordance between benthic community and sediment toxicity study results At the four stations for which there are both sediment toxicity test data and benthic community data those results are contradictory The sediment toxicity tests show a toxic response for most endpoints (especially at Stations 7 and 8) whereas the benthic community analyses do not (see Figure D4-15) GE recommends that the ERA be revised to discuss this point in the uncertainty section and also to carry this through to the conclusions in terms of the ability to extrapolate the potential for adverse effects to downstream locations

Inconsistent patterns oftPCB concentrations in sediment and tissues The ERA likewise does not discuss the fact that the median tPCB concentrations in sediments and those in tissue are not consistent (eg elevated tPCB concentrations in sediments were not co-located with those in tissue) (compare Figure 33-3 on p 3-18 with Figure 33-6 on p 3-22) These inconsistencies raise questions regarding the reliability of using median sediment concentrations as a measure of exposure for benthic invertebrates They also limit the usefulness of the biota sediment accumulation factors (BSAFs) which range from 08 to 61 (p D-32) in predicting tissue levels from sediment concentrations These inconsistencies should be acknowledged in the discussion of tissue chemistry (Section 335 pp 3-21 and 3-23) and the implications relative to estimating exposure should be addressed in the uncertainty section

Calculation of LC$o and ICso values The toxicity test endpoints presented in Tables D4-1 through D4-3 based on statistical analyses have a number of significant uncertainties Specifically uncertainties are associated with the results in which (a) the chi-square value exceeds the critical value in the derivation of LCjos and LC2os (20 out of 54 endpoints) (b) visual observations rather than the probit analyses were used because the model did not converge (2 out of 54 endpoints) and (c) there was an interrupted dose-response (9 of 54 endpoints) These difficulties with the statistical analyses are indicative of inconsistencies in the dose-response relationships that result in uncertainty surrounding the threshold values These uncertainties should be addressed (Tables D4-1 - D4-3) In addition no explanation is provided for why the highest dose (772 mgkg) for H azteca 48-h survival is excluded from the effects threshold analysis (Table D4-1) Additional information should be included regarding its exclusion or the analyses should be redone using the results of this treatment

Use of single samples to characterize sediment in used in bioassays A discussion of the uncertainty associated with determining exposure values of sediment composites used in toxicity testing based on a single chemistry sample should be provided (p D-17) Alternatively if multiple samples were used to evaluate potential heterogeneity in these composites to confirm that sediment was completely mixed then those data should be provided

315 Need for Additional Clarification and Information This section describes a number of issues for which the next draft of the ERA should provide clarification or additional data or analyses

Tissue effects thresholds from the literature The ERA states that the literature review was focused on Aroclor 1260 and 1254 (p 3-14) It should be revised to state that no effects thresholds were found based on studies with Aroclor 1260 and that only studies of tPCBs Aroclor 1254 and Clophen A50 were used to derive these thresholds The figures summarizing the literature effects thresholds should also be revised to indicate which study is associated with the effects reported (eg in Figure 44-13)

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and to indicate that studies with Clophen A50 are included in the summary In addition congenershyspecific studies should be removed from the literature review (Table D3-5 and Attachment DI) as they are not appropriate surrogates for tPCB toxicity

Multi-dimensional scaling analysis The results of the multi-dimensional scaling (MDS) statistical analyses used to develop Figures D3-15 through D3-17 should be presented This will provide important information regarding the relative contribution of different factors in this multivariate analysis

Derivation of MATCs The ERA does not explain explicitly how the sediment MATC of 3 mgkg tPCB (p 3-72) used to assess the extent of risks downstream from the PSA was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should specifically document the derivation of the MATC value used

32 Amphibians In the assessment of amphibians the ERA derives toxicity thresholds (MATCs) of 1 mgkg in both tissue (based on the literature) and sediments (based on the results of EPAs wood frog study) As discussed below GE believes that neither of these thresholds is supported by the underlying studies and that they should be higher Moreover in evaluating the results of the wood frog study the ERA does not consider certain endpoints (metamorphosis and mortality) that have clear ecological relevance these endpoints should be included in the evaluation In addition as further discussed in these comments we urge EPA to (a) give lower weight to the results of the leopard frog study and explicitly recognize its use of external reference frogs (b) recognize additional specified uncertainties in the amphibian assessment (c) clarify or present additional data or analyses on certain issues (d) modify the extrapolation to reaches downstream of Woods Pond and (e) correct an error in the text1

321 Lack of Literature Support for a Toxicity Threshold of 1 mgkg tPCBs in Tissue The ERA specifies a toxicity threshold of 1 mgkg in tissue based on a review of the literature (pp 4shy75 E-96) The studies and results used in this review are summarized in Figures 44-13 and E3-37 However the two tPCB LOAELs (called LOELs in these figures) below 1 mgkg shown in these figures are not supported by the underlying study (Gutleb et al 2000) One of these effects levels for time to metamorphosis for the African clawed frog is based on exposure to PCB 126 although tissue chemistry was analyzed as tPCBs Comparing tPCB concentrations to effects levels from a study in which larvae were exposed to PCB 126 would substantially overstate tPCB toxicity and hence this effect level should not be used to evaluate potential tPCB effects The second LOAEL for the European common frog is 024 mgkg tPCBs (wet weight2) in tissue (based on exposure to Clophen A50) However at that concentration there was no adverse effect body weight in the exposed frogs was higher not lower than in the control frogs In fact there was no significant effect on body weight at the highest tissue concentration used in this study (112 mgkg tPCBs wet weight) Hence the latter

1 As noted in Section 1 EPA has also agreed to include the frog study sponsored by GE (Resetarits 2002) in the next draft of the ERA In addition GE has recently completed a study of leopard frog egg masses in the PSA and is providing a report on that study to EPA (ARCADIS 2003) That study should likewise be included in the next draft of the ERA

2 As converted from lipid weight in Attachment E2

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value should be reported as an unbounded NOAEL for that endpoint and the value reported as a LOAEL (024 mgkg) should be removed from these figures

Additional concerns associated with the summary of the literature effects are related to the interpretation of the frequency of occurrence of adverse effects (p 4-56 and E-81) First three LOAELs are cited for mortality based on a single experiment (Savage et al 2002) (Figure 4431 p 4shy57 and E3-37 p 60) By definition a LOAEL is the lowest concentration in an experiment for which there is a statistically significant difference relative to the control therefore only the LOAEL at approximately 6 mgkg from this study should be included in this figure When the erroneous LOAEL (Gutleb et al 2000) and the redundant LOAELs (Savage et al 2002) are removed the frequency of adverse effect analysis indicates that 4 out of 12 endpoints (for tPCBs) or 33 demonstrate adverse effects at concentrations greater than 1 mgkg and that in fact no adverse effects are observed below 6 mgkg

In addition the meaning of this frequency of adverse effects is not clear because there are substantive differences between the nature of effects observed For example the endpoints of reduced activity or swimming speed may or may not have the same severity of impact to an individual as increased mortality This distinction is lost in a simple evaluation of frequency of effects between different endpoints in various literature studies

Based on the above discussion the statement that [tjhere were six instances of adverse effects occurring between 1 and 10 mgkg (pp 4-56 and E-81) should be revised For tPCBs there are only three LOAELs (ie incidence of adverse effects) between 1 and 10 mgkg and all them are at or above 6 mgkg The text should be revised accordingly If the interpretation of these studies based on the frequency of adverse effects is retained that text should also be revised and uncertainties associated with direct comparisons of the different kinds of effects included in this analysis should be acknowledged

322 Lack of Support for a Sediment Toxicity Threshold of 1 mgkg Based on Wood Frog Study

The sediment toxicity threshold of 1 mgkg is apparently based primarily on an analysis of the results of EPAs wood frog study However the description of the results of that study states that [e]cologically significant adverse effects in late stage juvenile wood frogs occurred in the sediment tPCB concentration range of 10 to 60 mgkg although responses of lesser magnitude yet statistically significant were observed at 5 mgkg tPCB and lower (p 4-60) The latter statement (which may be the basis for the threshold) is apparently derived from the wood frog NOAELs and LOAELs presented in Table E4-2 However there are several problems or inconsistencies in the derivation of site-specific NOAELs and LOAELs presented in Table E4-2

bull In several instances the NOAELs and LOAELs do not coincide with sediment concentrations that are associated with the effects data For example the spatially weighted mean tPCB value of 136 mgkg is presented as either a NOAEL or LOAEL for all four endpoints in Table E4-2 However it appears that this value is associated with a vernal pool (46-VP-4 Table E2-8) that has no effects data associated with it (see Tables E3-5- E3-6 and E 310 - E3-11)

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bull It appears that the reference WML-1 has been excluded from the calculation of NOAELs and LOAELs for Phase III metamorphs because of zero response at this concentration(Table E4-2) This exclusion is not warranted While the text refers to the tissue tPCB concentration for reference location WML-1 in the Phase III of the wood frog study as anomalous (eg p 4-52) no problems with data quality are reported that would indicate that the organism did not in fact have a tissue burden of 44 mgkg tPCBs As a result responses associated with this exposure level should be considered to represent part of the range of effects and all analyses of exposure and effect should include this reference site Statistical comparisons with a zero value are commonly made using a value marginally greater than zero (eg 000001)

bull Concentration-response relationships for each endpoint were evaluated using both (1) the most synoptic chemistry value paired with each toxicity endpoint (also referred to as vernal pool sediment) and (2) a combined data set used to generate a spatially weighted surface average (pp 4shy16 mdash 4-17) Given the variability in sediment concentrations the samples used in the laboratory toxicity study should not be assumed to be equivalent to the surface weighted average The synoptic (ie vernal pool) data reflect the actual tPCB concentrations measured in sediments used in the laboratory exposures and should thus should be used for analyses of the Phase I wood frog study which was conducted in the laboratory The surface weighted averages should be used for the analysis of Phase II and Phase III studies in which larvae and metamorphs were exposed in the field as they encompass the range of concentrations to which the growing larvae and metamorphs might have been exposed to The NOAELs LOAELs and point estimates for effects concentrations (eg LC50 and LC20) (Table E4-2) should be revised accordingly

bull Table E4-2 states that the reference site had no malformed specimens (Phase II metamorphs percent malformed) In fact Table E3-11 indicates that reference site WML-3 had 29 malformations

Moreover the toxicity threshold for wood frogs was derived based only on endpoints that showed effects The ERA states that if no discern[i]ble differences in effect levels across treatments were observed (ie inadequate range in response variable) the effects endpoint was not considered in the detailed statistical evaluation (p E-90) As a result as discussed in the next section the lack of PCB-related effects for key endpoints (ie mortality and metamorphosis) were not considered in the derivation of the effects threshold Consideration of the results for those omitted endpoints shows further that the sediment MATC of 1 mgkg is too low

We also note that although Appendix E presents tissue-based HQs for leopard frogs and wood frogs (pp E-96 - E-98) Section 12 of the ERA presents only sediment-based HQs (Figures 122-1 and p 12shy7) Tissue concentrations provide a more direct measure of exposure than do sediment concentrations and hence the tissue-based rather than sediment-based HQs should be used in Section 12

323 Need to Consider Additional Relevant Endpoints in Wood Frog Study As noted above in evaluating the results of the wood frog study two endpoints with clear ecological relevance ~ metamorphosis and mortality -- were screened out of the formal concentration-response modeling due to a lack of discern[i]ble differences in effect levels across treatments (p E-90) However these two endpoints integrate other effects (ie the most serious effect of malformations would be reduced metamorphosis and increased mortality) and should be carried through the

concentration-response evaluation If no concentration-response curve can be derived because there were no effects then the highest dose should be treated as a NOAEL for these endpoints the LC50

should be expressed as gt highest dose and both mortality and metamorphosis should be considered subsequently as part of the lines-of-evidence evaluation

324 Evaluation of the Leopard Frog Study EPAs leopard frog study receives the same overall weight (moderatehigh) as its wood frog study in the weight-of evidence-evaluation (Table 45-4 p 4-69) Considering the significant problems with the leopard frog study as detailed in GEs comments on this study (BBL Sciences et al 2003a) it should be accorded a low weight

Moreover the text does not consistently acknowledge that reference frogs for the leopard frog study were obtained from a biological supply company For readers unfamiliar with the underlying study this could lead to misinterpretations of the results presented The text should be modified to clearly represent this aspect of the leopard frog study as well as additional qualifications as follows

bull The first time the study design of the leopard frog study is presented it should be clearly stated that no frogs or eggslarvae were found in the reference areas (p 4-13)

bull The text that describes comparisons between both the toxicity studies and the community evaluations and appropriately matched field references (p 4-27) should be revised to indicate that for the leopard frog study the field reference was limited to sediment not frogs collected from a reference pond

bull Although the text states that reference ponds were surveyed for eggs and larvae it does not indicate that in addition to no eggs or larvae being found at four of nine contaminated sites none were found at the reference sites (p 4-35)

bull Similarly the summary of female leopard frog reproductive fitness identifies all of the Housatonic River sites that were not gravid (did not have eggs mature enough for successful fertilization) (p 4shy30) It should also indicate that R2 (external reference) did not have any successful fertilization

325 Need to Acknowledge Additional Uncertainties While the ERA acknowledges some uncertainties associated with the amphibian studies (pp 4-70 4shy73 E-108-110) other critical uncertainties are not acknowledged For example there are uncertainties associated with the concentration-response analysis (eg ECsos ECaos) based on the poor fit of the data in the probit analysis Contrary to the statement that most endpoints followed a fairly smooth concentration-response (text box p 4-60) Table E4-2 indicates that only one of 11 of the ECsos presented (ie Phase III metamorph percent malformed based on comparisons with the lowest vernal pool sediment tPCB concentration) appears to be appropriately described by the probit analysis The other ECsos were described as (a) outside data range confidence limits increase (111) (b) probit model had poor fit to data confidence limits increase (111) (c) calculated with linear interpolation no confidence limits can be calculated (311) and (d) based on visual inspection of data (511) These uncertainties should be recognized

326 Need for Additional Information There are a number of issues on which we urge EPA to provide additional information in the next draft of the ERA

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Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

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Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

261 Risk Comparisons across Species The ERA qualitatively extrapolates predicted risks for each receptor to other species within the same feeding guild based on factors that influence exposure to COPCs (eg diet foraging range body weight) There are a number of problems with this approach First in the absence of data on the other species these extrapolations are not supported by any actual evidence Second these extrapolations of risk do not recognize that risk is a function not only of exposure but also of toxicological sensitivity By making the extrapolations based on factors that relate solely to exposure the ERA implies that all species within a feeding guild are equally sensitive to the toxicological effects of the COPCs However as demonstrated by Brunstrom and Lund (1988) toxicological sensitivity can vary by orders of magnitude across species even for species in the same feeding guild and taxonomic order (eg chickens and turkeys) Hence these analyses should not be referred to as comparisons of risk

The interspecies extrapolations also do not account for field data that either support or refute qualitative conclusions regarding relative risks For example data collected by the Massachusetts Division of Fisheries and Wildlife since 1980 on the productivity of great blue herons throughout Massachusetts show no differences in the numbers of young per nest for herons breeding within or beyond foraging distance of the PSA (MDFW 1979 1980 1981 1982 1983 1984 1985 1986ab 1987 1989 1991 1996) This finding does not support the ERAs qualitative finding that great blue herons face similar to higher risks than American bitterns which are predicted to have high risks (p 12-36)

GE recommends that extrapolations of risk estimates from receptors of interest to other species be omitted from the ERA because they are too uncertain to provide useful information If they are retained GE recommends that the comparisons be accurately characterized as comparisons of potential exposure rather than as comparisons of risk Regardless of how the extrapolations are presented however uncertainties should be explicitly reported including both the inability of the analysis to account for interspecies differences in toxicological sensitivity and cases where available field data contradict the extrapolated findings

262 Extrapolations to Downstream Reaches The field studies surveys and sampling program conducted for the ERA primarily focus on the PSA In an effort to apply the analyses across the entire study area the ERA extrapolates risks downstream of the PSA for seven receptors (benthic invertebrates amphibians warm water fish trout mink otter and bald eagles) For each of these groups the ERA identifies a maximum acceptable threshold concentration (MATC) for total PCBs (tPCBs) Each MATC is then compared to exposure concentrations for individual river and floodplain reaches downstream of Woods Pond to Long Island Sound Areas where exposure concentrations exceed the MATCs are interpreted as indicating potential risks

GE recommends several improvements in this approach (a) revision of the MATCs (b) improved spatial resolution of the overlap between predictions of risk to each receptor and the availability of suitable habitat for those receptors and (c) an explicit discussion of the uncertainties associated with these extrapolations In addition more complete documentation of the methodologies and assumptions employed would enhance the transparency of the analysis

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First several of the MATCs (eg for benthic invertebrates amphibians fish and bald eagles) are not supported by the site-specific studies or the scientific literature Specific concerns related to the basis for these MATCs are discussed below in Sections 311 (benthic invertebrates) 321 amp 322 (amphibians) 332 amp 333 (fish) and 3822 (bald eagles) GE recommends that these MATCs be revised

Second the applicability of the benchmark comparisons for each of the seven receptors should also be considered relative to the available habitat for such receptors in the downstream reaches For example although the MATC for amphibians was developed based on sediment tPCB concentrations in breeding ponds it was applied downstream of Woods Pond to soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data in the downstream reaches (p 12-15) Although such data may be lacking the ERA should make clear that the extrapolation applies only to sediment in potential floodplain ponds downstream of Woods Pond In addition risks to mink otters and bald eagles are evaluated for all reaches of the river with adequate data on exposure concentrations regardless of habitat Restricting the assessment of risks for these receptors to those reaches with suitable habitat would further improve the accuracy of these extrapolations

Third uncertainties in the extrapolations should be discussed and the results should be subjected to a separate weight-of-evidence evaluation

Finally the ERA does not provide enough information regarding the actual methodologies and assumptions used in the analysis of risks downstream of Woods Pond Transparency in this analysis is of paramount importance given the potential influence and use of these extrapolated risk results In particular the ERA should report the actual exposure concentrations used and whether they are spatially weighted averages arithmetic averages 95 upper confidence limits (UCLs) maxima etc In addition EPA should provide at least general information regarding the suitability of the downstream habitat for these receptors or where such information does not exist acknowledge that habitat has not been evaluated and could have a significant effect on any risks downstream of Woods Pond

27 Characterization of GEs Position In several places (pp 2-60 2-61) the ERA characterizes GEs position GE requests that such descriptions of GEs position be removed from the ERA GE will present its position in its comments during the public comment period andor to the Peer Review Panel

28 Non-PCB Constituents The ERA covers the Rest of River which is defined in the Consent Decree (Paragraph 6) as the Housatonic River and its sediments and floodplain areas downstream of the Confluence of the East and West Branches of the Housatonic River including backwaters except for ActualPotential Lawns to the extent that such areas are areas to which Waste Materials that originated at the GE Plant Area have migrated and which are being investigated or remediated pursuant to this Consent Decree (emphasis added) The Revised RCRA Permit contains a similar definition (Definition 19) limiting the Rest of River areas to areas to which releases of hazardous wastes andor hazardous constituents are migrating or have migrated from the GE Facility

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The ERA recognizes that the Rest of River includes areas of the Housatonic River and its sediments and floodplain (except ActualPotential Lawns) in which contaminants migrating from the GE facility are located (p 1-2) However it includes as COPCs a number of non-PCB constituents that are or may not be related to releases from the GE facility These include for various media numerous polycyclic aromatic hydrocarbons (PAHs) and other semi-volatile organic compounds (SVOCs) dioxins and furans several metals and (for fish) certain pesticides (Tables 24-2 through 24-5) There are multiple potential sources of these constituents in the Rest of River area not just releases from the GE facility

To avoid any confusion the ERA should make clear in its discussions of the COPCs (Sections 231 and 243) that while several COPCs other than PCBs have been selected for the ERA there are multiple potential sources of these constituents and hence there is no evidence demonstrating that the occurrence of these COPCs in the Rest of River area is necessarily derived from releases attributable to GE

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3 Specific Comments

31 Benthic Invertebrates In its assessment of benthic invertebrates the ERA derives toxicity thresholds (MATCs) of 3 mgkg tPCB in both tissue (based on the literature) and sediments (based on the results of toxicity and benthic community studies) GE believes that these thresholds should be reevaluated As discussed in this section GE urges EPA to make the following changes to the ERAs assessment of benthic invertebrates (a) use a different data set to calculate sediment-based toxicity thresholds (b) take adequate account of sediment grain size in interpreting the benthic community and toxicity test results (c) reduce the emphasis on Sediment Quality Values and the Toxicity Identification Evaluation (TIE) results (d) recognize a number of additional specified uncertainties and (e) clarify or provide additional information on certain issues

311 Concentration-Response Analysis to Derive Sediment Toxicity Thresholds The ERA concludes that the toxicity studies showed ecologically significant effects at sediment tPCB concentrations of 3 mgkg or higher (pp 3-71 D-98) the proposed MATC for sediment This proposed toxicity threshold is apparently based on LCso and ICso values from laboratory studies that were calculated based on the median values of multiple grab samples (p D-10) (some of which were collected independently of the laboratory bioassays) rather than based on measured concentrations of PCBs in sediments actually used in these bioassays The use of these unrelated data as a basis for establishing exposure levels in laboratory bioassays is of concern given that PCB concentrations in sediments of the Housatonic River can vary by orders of magnitude over very small spatial and temporal scales (pp D-26 to D-28) The rationale given for this method is that combining data from sampling events that are approximately (but not exactly) synoptic with the effects data more accurately portrays the COC concentrations at each station (p D-27) This approach may provide an indication of PCB concentrations in the vicinity of a station over time but it does not provide a better measure of PCB concentrations in the specific composites used in the bioassays than would a direct measure of PCBs in the sediments used in the bioassays For some stations concentrations measured directly from the composites are in fact substantially different than those derived from other collection efforts (Figures D3-1 through D3-5 Stations 7 and 8A) resulting in variability which likely substantially affects the exposure-response analyses and resulting LCsos and ICsoS Because of this variability it is important that effects levels for bioassay tests be calculated from the data that represent the concentrations to which these organisms were actually exposed

GE recommends that the ERA be revised to calculate the No Observed Adverse Effect Levels (NOAELs) Lowest Observed Adverse Effect Levels (LOAELs) and LCsoICso values for the laboratory bioassays (Tables D4-2 and D4-3) based on the synoptic values derived directly from the composite samples for the laboratory bioassays because these values best represent the exposures to the test organisms The LCao and IC20 values should also be revised in a similar manner as should the linear regression models (Table D4-4 Figure D4-5)

312 Effects of Grain Size on Study Interpretation Grain size is a significant variable that can impact both benthic community structure and the endpoints evaluated in the laboratory toxicity studies However in several instances the ERA does not adequately consider the effects of grain size in interpreting the study results

The ERA states that the benthic community data indicated that five of the six stations with median tPCB concentrations above 5 mgkg had significant benthic community alteration (p D-98) Those same five stations had coarse-grained sediments (see Figures D4-6 and D4-7) The one fine-grained station with median tPCB concentrations greater than 5 mgkg (Station 8) had higher species richness and abundance than the coarse-grained stations and was not significantly different from the reference stations (see Figures D4-6 D4-7 and D4-15) Benthic invertebrates tend to be the least diverse and the least abundant in sand likely due to its instability (Ward 1992 Minshall 1984 Allan 1995) Thus even in the absence of PCBs the diversity and abundance of invertebrates would be expected to be lower at the coarse-grained stations In these circumstances it is at least equally likely that grain size rather than PCB concentration explains the spatial variations in benthic community structure As a result the statements throughout the ERA regarding the high level of confidence in the conclusion that benthic invertebrates in the Housatonic River experience unacceptable risks due to tPCBs (eg p 12-55) are not be supported Those statements should be revised to recognize the confounding impacts and uncertainty associated with grain size effects and to note that as a result the benthic community data do not provide conclusive evidence of tPCB effects on changes in community structure

Similar concerns apply to the bioassay test The reference stations used in the bioassay test (Al and A3) are coarse-grained (Figure D2-2) whereas the treatment stations showing the highest levels of response (Stations 7 8 and 8A) are fine-grained Statistical analyses and the weight of evidence evaluation are based on comparisons made between Housatonic River sediment stations and references regardless of grain size (Table D3-4 and Figure D4-15) The uncertainty associated with comparing the toxicity of fine-grained stations to coarse-grained reference treatments should be acknowledged

313 Use of Sediment Quality Values and Toxicity Identification Evaluation in the Weight-of-Evidence

The ERA also relies on published Sediment Quality Values (SQVs) to support a sediment toxicity threshold value of 3 to 5 mgkg (pp 3-71 D-98) SQVs are generic in nature and therefore are primarily appropriate in screening-level ERAs when no site-specific data are available (see eg Long et al 1995) Given the availability of substantial site-specific data the generic SQVs should not be used at all or at a minimum given very low weight and the references to them should be removed from the conclusions

The ERA also gives moderate weight to the results of the Toxicity Identification Evaluation (TIE) (Table D4-5) The ERA concludes from this Phase I TIE that PCBs may be the main causal agent in the toxicity studies (p D-78) However the TIE was not a definitive study and was not designed to provide an independent evaluation of effects and the results of the TIE are inconclusive showing only that non-polar organic chemicals were likely responsible for the observed toxicity As a result while the results of the TIE provide some evidence as to the degree to which observed effects can be linked to PCBs rather than other COPCs the TIE study should be removed as a separate line of evidence

314 Need to Acknowledge Additional Uncertainties There are a number of uncertainties associated with the benthic invertebrate studies Some of these are acknowledged in the text (pp D-95 through D-98) but other critical uncertainties are not The text should be revised to acknowledge the following uncertainties

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Lack of concordance between benthic community and sediment toxicity study results At the four stations for which there are both sediment toxicity test data and benthic community data those results are contradictory The sediment toxicity tests show a toxic response for most endpoints (especially at Stations 7 and 8) whereas the benthic community analyses do not (see Figure D4-15) GE recommends that the ERA be revised to discuss this point in the uncertainty section and also to carry this through to the conclusions in terms of the ability to extrapolate the potential for adverse effects to downstream locations

Inconsistent patterns oftPCB concentrations in sediment and tissues The ERA likewise does not discuss the fact that the median tPCB concentrations in sediments and those in tissue are not consistent (eg elevated tPCB concentrations in sediments were not co-located with those in tissue) (compare Figure 33-3 on p 3-18 with Figure 33-6 on p 3-22) These inconsistencies raise questions regarding the reliability of using median sediment concentrations as a measure of exposure for benthic invertebrates They also limit the usefulness of the biota sediment accumulation factors (BSAFs) which range from 08 to 61 (p D-32) in predicting tissue levels from sediment concentrations These inconsistencies should be acknowledged in the discussion of tissue chemistry (Section 335 pp 3-21 and 3-23) and the implications relative to estimating exposure should be addressed in the uncertainty section

Calculation of LC$o and ICso values The toxicity test endpoints presented in Tables D4-1 through D4-3 based on statistical analyses have a number of significant uncertainties Specifically uncertainties are associated with the results in which (a) the chi-square value exceeds the critical value in the derivation of LCjos and LC2os (20 out of 54 endpoints) (b) visual observations rather than the probit analyses were used because the model did not converge (2 out of 54 endpoints) and (c) there was an interrupted dose-response (9 of 54 endpoints) These difficulties with the statistical analyses are indicative of inconsistencies in the dose-response relationships that result in uncertainty surrounding the threshold values These uncertainties should be addressed (Tables D4-1 - D4-3) In addition no explanation is provided for why the highest dose (772 mgkg) for H azteca 48-h survival is excluded from the effects threshold analysis (Table D4-1) Additional information should be included regarding its exclusion or the analyses should be redone using the results of this treatment

Use of single samples to characterize sediment in used in bioassays A discussion of the uncertainty associated with determining exposure values of sediment composites used in toxicity testing based on a single chemistry sample should be provided (p D-17) Alternatively if multiple samples were used to evaluate potential heterogeneity in these composites to confirm that sediment was completely mixed then those data should be provided

315 Need for Additional Clarification and Information This section describes a number of issues for which the next draft of the ERA should provide clarification or additional data or analyses

Tissue effects thresholds from the literature The ERA states that the literature review was focused on Aroclor 1260 and 1254 (p 3-14) It should be revised to state that no effects thresholds were found based on studies with Aroclor 1260 and that only studies of tPCBs Aroclor 1254 and Clophen A50 were used to derive these thresholds The figures summarizing the literature effects thresholds should also be revised to indicate which study is associated with the effects reported (eg in Figure 44-13)

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and to indicate that studies with Clophen A50 are included in the summary In addition congenershyspecific studies should be removed from the literature review (Table D3-5 and Attachment DI) as they are not appropriate surrogates for tPCB toxicity

Multi-dimensional scaling analysis The results of the multi-dimensional scaling (MDS) statistical analyses used to develop Figures D3-15 through D3-17 should be presented This will provide important information regarding the relative contribution of different factors in this multivariate analysis

Derivation of MATCs The ERA does not explain explicitly how the sediment MATC of 3 mgkg tPCB (p 3-72) used to assess the extent of risks downstream from the PSA was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should specifically document the derivation of the MATC value used

32 Amphibians In the assessment of amphibians the ERA derives toxicity thresholds (MATCs) of 1 mgkg in both tissue (based on the literature) and sediments (based on the results of EPAs wood frog study) As discussed below GE believes that neither of these thresholds is supported by the underlying studies and that they should be higher Moreover in evaluating the results of the wood frog study the ERA does not consider certain endpoints (metamorphosis and mortality) that have clear ecological relevance these endpoints should be included in the evaluation In addition as further discussed in these comments we urge EPA to (a) give lower weight to the results of the leopard frog study and explicitly recognize its use of external reference frogs (b) recognize additional specified uncertainties in the amphibian assessment (c) clarify or present additional data or analyses on certain issues (d) modify the extrapolation to reaches downstream of Woods Pond and (e) correct an error in the text1

321 Lack of Literature Support for a Toxicity Threshold of 1 mgkg tPCBs in Tissue The ERA specifies a toxicity threshold of 1 mgkg in tissue based on a review of the literature (pp 4shy75 E-96) The studies and results used in this review are summarized in Figures 44-13 and E3-37 However the two tPCB LOAELs (called LOELs in these figures) below 1 mgkg shown in these figures are not supported by the underlying study (Gutleb et al 2000) One of these effects levels for time to metamorphosis for the African clawed frog is based on exposure to PCB 126 although tissue chemistry was analyzed as tPCBs Comparing tPCB concentrations to effects levels from a study in which larvae were exposed to PCB 126 would substantially overstate tPCB toxicity and hence this effect level should not be used to evaluate potential tPCB effects The second LOAEL for the European common frog is 024 mgkg tPCBs (wet weight2) in tissue (based on exposure to Clophen A50) However at that concentration there was no adverse effect body weight in the exposed frogs was higher not lower than in the control frogs In fact there was no significant effect on body weight at the highest tissue concentration used in this study (112 mgkg tPCBs wet weight) Hence the latter

1 As noted in Section 1 EPA has also agreed to include the frog study sponsored by GE (Resetarits 2002) in the next draft of the ERA In addition GE has recently completed a study of leopard frog egg masses in the PSA and is providing a report on that study to EPA (ARCADIS 2003) That study should likewise be included in the next draft of the ERA

2 As converted from lipid weight in Attachment E2

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value should be reported as an unbounded NOAEL for that endpoint and the value reported as a LOAEL (024 mgkg) should be removed from these figures

Additional concerns associated with the summary of the literature effects are related to the interpretation of the frequency of occurrence of adverse effects (p 4-56 and E-81) First three LOAELs are cited for mortality based on a single experiment (Savage et al 2002) (Figure 4431 p 4shy57 and E3-37 p 60) By definition a LOAEL is the lowest concentration in an experiment for which there is a statistically significant difference relative to the control therefore only the LOAEL at approximately 6 mgkg from this study should be included in this figure When the erroneous LOAEL (Gutleb et al 2000) and the redundant LOAELs (Savage et al 2002) are removed the frequency of adverse effect analysis indicates that 4 out of 12 endpoints (for tPCBs) or 33 demonstrate adverse effects at concentrations greater than 1 mgkg and that in fact no adverse effects are observed below 6 mgkg

In addition the meaning of this frequency of adverse effects is not clear because there are substantive differences between the nature of effects observed For example the endpoints of reduced activity or swimming speed may or may not have the same severity of impact to an individual as increased mortality This distinction is lost in a simple evaluation of frequency of effects between different endpoints in various literature studies

Based on the above discussion the statement that [tjhere were six instances of adverse effects occurring between 1 and 10 mgkg (pp 4-56 and E-81) should be revised For tPCBs there are only three LOAELs (ie incidence of adverse effects) between 1 and 10 mgkg and all them are at or above 6 mgkg The text should be revised accordingly If the interpretation of these studies based on the frequency of adverse effects is retained that text should also be revised and uncertainties associated with direct comparisons of the different kinds of effects included in this analysis should be acknowledged

322 Lack of Support for a Sediment Toxicity Threshold of 1 mgkg Based on Wood Frog Study

The sediment toxicity threshold of 1 mgkg is apparently based primarily on an analysis of the results of EPAs wood frog study However the description of the results of that study states that [e]cologically significant adverse effects in late stage juvenile wood frogs occurred in the sediment tPCB concentration range of 10 to 60 mgkg although responses of lesser magnitude yet statistically significant were observed at 5 mgkg tPCB and lower (p 4-60) The latter statement (which may be the basis for the threshold) is apparently derived from the wood frog NOAELs and LOAELs presented in Table E4-2 However there are several problems or inconsistencies in the derivation of site-specific NOAELs and LOAELs presented in Table E4-2

bull In several instances the NOAELs and LOAELs do not coincide with sediment concentrations that are associated with the effects data For example the spatially weighted mean tPCB value of 136 mgkg is presented as either a NOAEL or LOAEL for all four endpoints in Table E4-2 However it appears that this value is associated with a vernal pool (46-VP-4 Table E2-8) that has no effects data associated with it (see Tables E3-5- E3-6 and E 310 - E3-11)

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bull It appears that the reference WML-1 has been excluded from the calculation of NOAELs and LOAELs for Phase III metamorphs because of zero response at this concentration(Table E4-2) This exclusion is not warranted While the text refers to the tissue tPCB concentration for reference location WML-1 in the Phase III of the wood frog study as anomalous (eg p 4-52) no problems with data quality are reported that would indicate that the organism did not in fact have a tissue burden of 44 mgkg tPCBs As a result responses associated with this exposure level should be considered to represent part of the range of effects and all analyses of exposure and effect should include this reference site Statistical comparisons with a zero value are commonly made using a value marginally greater than zero (eg 000001)

bull Concentration-response relationships for each endpoint were evaluated using both (1) the most synoptic chemistry value paired with each toxicity endpoint (also referred to as vernal pool sediment) and (2) a combined data set used to generate a spatially weighted surface average (pp 4shy16 mdash 4-17) Given the variability in sediment concentrations the samples used in the laboratory toxicity study should not be assumed to be equivalent to the surface weighted average The synoptic (ie vernal pool) data reflect the actual tPCB concentrations measured in sediments used in the laboratory exposures and should thus should be used for analyses of the Phase I wood frog study which was conducted in the laboratory The surface weighted averages should be used for the analysis of Phase II and Phase III studies in which larvae and metamorphs were exposed in the field as they encompass the range of concentrations to which the growing larvae and metamorphs might have been exposed to The NOAELs LOAELs and point estimates for effects concentrations (eg LC50 and LC20) (Table E4-2) should be revised accordingly

bull Table E4-2 states that the reference site had no malformed specimens (Phase II metamorphs percent malformed) In fact Table E3-11 indicates that reference site WML-3 had 29 malformations

Moreover the toxicity threshold for wood frogs was derived based only on endpoints that showed effects The ERA states that if no discern[i]ble differences in effect levels across treatments were observed (ie inadequate range in response variable) the effects endpoint was not considered in the detailed statistical evaluation (p E-90) As a result as discussed in the next section the lack of PCB-related effects for key endpoints (ie mortality and metamorphosis) were not considered in the derivation of the effects threshold Consideration of the results for those omitted endpoints shows further that the sediment MATC of 1 mgkg is too low

We also note that although Appendix E presents tissue-based HQs for leopard frogs and wood frogs (pp E-96 - E-98) Section 12 of the ERA presents only sediment-based HQs (Figures 122-1 and p 12shy7) Tissue concentrations provide a more direct measure of exposure than do sediment concentrations and hence the tissue-based rather than sediment-based HQs should be used in Section 12

323 Need to Consider Additional Relevant Endpoints in Wood Frog Study As noted above in evaluating the results of the wood frog study two endpoints with clear ecological relevance ~ metamorphosis and mortality -- were screened out of the formal concentration-response modeling due to a lack of discern[i]ble differences in effect levels across treatments (p E-90) However these two endpoints integrate other effects (ie the most serious effect of malformations would be reduced metamorphosis and increased mortality) and should be carried through the

concentration-response evaluation If no concentration-response curve can be derived because there were no effects then the highest dose should be treated as a NOAEL for these endpoints the LC50

should be expressed as gt highest dose and both mortality and metamorphosis should be considered subsequently as part of the lines-of-evidence evaluation

324 Evaluation of the Leopard Frog Study EPAs leopard frog study receives the same overall weight (moderatehigh) as its wood frog study in the weight-of evidence-evaluation (Table 45-4 p 4-69) Considering the significant problems with the leopard frog study as detailed in GEs comments on this study (BBL Sciences et al 2003a) it should be accorded a low weight

Moreover the text does not consistently acknowledge that reference frogs for the leopard frog study were obtained from a biological supply company For readers unfamiliar with the underlying study this could lead to misinterpretations of the results presented The text should be modified to clearly represent this aspect of the leopard frog study as well as additional qualifications as follows

bull The first time the study design of the leopard frog study is presented it should be clearly stated that no frogs or eggslarvae were found in the reference areas (p 4-13)

bull The text that describes comparisons between both the toxicity studies and the community evaluations and appropriately matched field references (p 4-27) should be revised to indicate that for the leopard frog study the field reference was limited to sediment not frogs collected from a reference pond

bull Although the text states that reference ponds were surveyed for eggs and larvae it does not indicate that in addition to no eggs or larvae being found at four of nine contaminated sites none were found at the reference sites (p 4-35)

bull Similarly the summary of female leopard frog reproductive fitness identifies all of the Housatonic River sites that were not gravid (did not have eggs mature enough for successful fertilization) (p 4shy30) It should also indicate that R2 (external reference) did not have any successful fertilization

325 Need to Acknowledge Additional Uncertainties While the ERA acknowledges some uncertainties associated with the amphibian studies (pp 4-70 4shy73 E-108-110) other critical uncertainties are not acknowledged For example there are uncertainties associated with the concentration-response analysis (eg ECsos ECaos) based on the poor fit of the data in the probit analysis Contrary to the statement that most endpoints followed a fairly smooth concentration-response (text box p 4-60) Table E4-2 indicates that only one of 11 of the ECsos presented (ie Phase III metamorph percent malformed based on comparisons with the lowest vernal pool sediment tPCB concentration) appears to be appropriately described by the probit analysis The other ECsos were described as (a) outside data range confidence limits increase (111) (b) probit model had poor fit to data confidence limits increase (111) (c) calculated with linear interpolation no confidence limits can be calculated (311) and (d) based on visual inspection of data (511) These uncertainties should be recognized

326 Need for Additional Information There are a number of issues on which we urge EPA to provide additional information in the next draft of the ERA

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Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

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Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

First several of the MATCs (eg for benthic invertebrates amphibians fish and bald eagles) are not supported by the site-specific studies or the scientific literature Specific concerns related to the basis for these MATCs are discussed below in Sections 311 (benthic invertebrates) 321 amp 322 (amphibians) 332 amp 333 (fish) and 3822 (bald eagles) GE recommends that these MATCs be revised

Second the applicability of the benchmark comparisons for each of the seven receptors should also be considered relative to the available habitat for such receptors in the downstream reaches For example although the MATC for amphibians was developed based on sediment tPCB concentrations in breeding ponds it was applied downstream of Woods Pond to soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data in the downstream reaches (p 12-15) Although such data may be lacking the ERA should make clear that the extrapolation applies only to sediment in potential floodplain ponds downstream of Woods Pond In addition risks to mink otters and bald eagles are evaluated for all reaches of the river with adequate data on exposure concentrations regardless of habitat Restricting the assessment of risks for these receptors to those reaches with suitable habitat would further improve the accuracy of these extrapolations

Third uncertainties in the extrapolations should be discussed and the results should be subjected to a separate weight-of-evidence evaluation

Finally the ERA does not provide enough information regarding the actual methodologies and assumptions used in the analysis of risks downstream of Woods Pond Transparency in this analysis is of paramount importance given the potential influence and use of these extrapolated risk results In particular the ERA should report the actual exposure concentrations used and whether they are spatially weighted averages arithmetic averages 95 upper confidence limits (UCLs) maxima etc In addition EPA should provide at least general information regarding the suitability of the downstream habitat for these receptors or where such information does not exist acknowledge that habitat has not been evaluated and could have a significant effect on any risks downstream of Woods Pond

27 Characterization of GEs Position In several places (pp 2-60 2-61) the ERA characterizes GEs position GE requests that such descriptions of GEs position be removed from the ERA GE will present its position in its comments during the public comment period andor to the Peer Review Panel

28 Non-PCB Constituents The ERA covers the Rest of River which is defined in the Consent Decree (Paragraph 6) as the Housatonic River and its sediments and floodplain areas downstream of the Confluence of the East and West Branches of the Housatonic River including backwaters except for ActualPotential Lawns to the extent that such areas are areas to which Waste Materials that originated at the GE Plant Area have migrated and which are being investigated or remediated pursuant to this Consent Decree (emphasis added) The Revised RCRA Permit contains a similar definition (Definition 19) limiting the Rest of River areas to areas to which releases of hazardous wastes andor hazardous constituents are migrating or have migrated from the GE Facility

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The ERA recognizes that the Rest of River includes areas of the Housatonic River and its sediments and floodplain (except ActualPotential Lawns) in which contaminants migrating from the GE facility are located (p 1-2) However it includes as COPCs a number of non-PCB constituents that are or may not be related to releases from the GE facility These include for various media numerous polycyclic aromatic hydrocarbons (PAHs) and other semi-volatile organic compounds (SVOCs) dioxins and furans several metals and (for fish) certain pesticides (Tables 24-2 through 24-5) There are multiple potential sources of these constituents in the Rest of River area not just releases from the GE facility

To avoid any confusion the ERA should make clear in its discussions of the COPCs (Sections 231 and 243) that while several COPCs other than PCBs have been selected for the ERA there are multiple potential sources of these constituents and hence there is no evidence demonstrating that the occurrence of these COPCs in the Rest of River area is necessarily derived from releases attributable to GE

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3 Specific Comments

31 Benthic Invertebrates In its assessment of benthic invertebrates the ERA derives toxicity thresholds (MATCs) of 3 mgkg tPCB in both tissue (based on the literature) and sediments (based on the results of toxicity and benthic community studies) GE believes that these thresholds should be reevaluated As discussed in this section GE urges EPA to make the following changes to the ERAs assessment of benthic invertebrates (a) use a different data set to calculate sediment-based toxicity thresholds (b) take adequate account of sediment grain size in interpreting the benthic community and toxicity test results (c) reduce the emphasis on Sediment Quality Values and the Toxicity Identification Evaluation (TIE) results (d) recognize a number of additional specified uncertainties and (e) clarify or provide additional information on certain issues

311 Concentration-Response Analysis to Derive Sediment Toxicity Thresholds The ERA concludes that the toxicity studies showed ecologically significant effects at sediment tPCB concentrations of 3 mgkg or higher (pp 3-71 D-98) the proposed MATC for sediment This proposed toxicity threshold is apparently based on LCso and ICso values from laboratory studies that were calculated based on the median values of multiple grab samples (p D-10) (some of which were collected independently of the laboratory bioassays) rather than based on measured concentrations of PCBs in sediments actually used in these bioassays The use of these unrelated data as a basis for establishing exposure levels in laboratory bioassays is of concern given that PCB concentrations in sediments of the Housatonic River can vary by orders of magnitude over very small spatial and temporal scales (pp D-26 to D-28) The rationale given for this method is that combining data from sampling events that are approximately (but not exactly) synoptic with the effects data more accurately portrays the COC concentrations at each station (p D-27) This approach may provide an indication of PCB concentrations in the vicinity of a station over time but it does not provide a better measure of PCB concentrations in the specific composites used in the bioassays than would a direct measure of PCBs in the sediments used in the bioassays For some stations concentrations measured directly from the composites are in fact substantially different than those derived from other collection efforts (Figures D3-1 through D3-5 Stations 7 and 8A) resulting in variability which likely substantially affects the exposure-response analyses and resulting LCsos and ICsoS Because of this variability it is important that effects levels for bioassay tests be calculated from the data that represent the concentrations to which these organisms were actually exposed

GE recommends that the ERA be revised to calculate the No Observed Adverse Effect Levels (NOAELs) Lowest Observed Adverse Effect Levels (LOAELs) and LCsoICso values for the laboratory bioassays (Tables D4-2 and D4-3) based on the synoptic values derived directly from the composite samples for the laboratory bioassays because these values best represent the exposures to the test organisms The LCao and IC20 values should also be revised in a similar manner as should the linear regression models (Table D4-4 Figure D4-5)

312 Effects of Grain Size on Study Interpretation Grain size is a significant variable that can impact both benthic community structure and the endpoints evaluated in the laboratory toxicity studies However in several instances the ERA does not adequately consider the effects of grain size in interpreting the study results

The ERA states that the benthic community data indicated that five of the six stations with median tPCB concentrations above 5 mgkg had significant benthic community alteration (p D-98) Those same five stations had coarse-grained sediments (see Figures D4-6 and D4-7) The one fine-grained station with median tPCB concentrations greater than 5 mgkg (Station 8) had higher species richness and abundance than the coarse-grained stations and was not significantly different from the reference stations (see Figures D4-6 D4-7 and D4-15) Benthic invertebrates tend to be the least diverse and the least abundant in sand likely due to its instability (Ward 1992 Minshall 1984 Allan 1995) Thus even in the absence of PCBs the diversity and abundance of invertebrates would be expected to be lower at the coarse-grained stations In these circumstances it is at least equally likely that grain size rather than PCB concentration explains the spatial variations in benthic community structure As a result the statements throughout the ERA regarding the high level of confidence in the conclusion that benthic invertebrates in the Housatonic River experience unacceptable risks due to tPCBs (eg p 12-55) are not be supported Those statements should be revised to recognize the confounding impacts and uncertainty associated with grain size effects and to note that as a result the benthic community data do not provide conclusive evidence of tPCB effects on changes in community structure

Similar concerns apply to the bioassay test The reference stations used in the bioassay test (Al and A3) are coarse-grained (Figure D2-2) whereas the treatment stations showing the highest levels of response (Stations 7 8 and 8A) are fine-grained Statistical analyses and the weight of evidence evaluation are based on comparisons made between Housatonic River sediment stations and references regardless of grain size (Table D3-4 and Figure D4-15) The uncertainty associated with comparing the toxicity of fine-grained stations to coarse-grained reference treatments should be acknowledged

313 Use of Sediment Quality Values and Toxicity Identification Evaluation in the Weight-of-Evidence

The ERA also relies on published Sediment Quality Values (SQVs) to support a sediment toxicity threshold value of 3 to 5 mgkg (pp 3-71 D-98) SQVs are generic in nature and therefore are primarily appropriate in screening-level ERAs when no site-specific data are available (see eg Long et al 1995) Given the availability of substantial site-specific data the generic SQVs should not be used at all or at a minimum given very low weight and the references to them should be removed from the conclusions

The ERA also gives moderate weight to the results of the Toxicity Identification Evaluation (TIE) (Table D4-5) The ERA concludes from this Phase I TIE that PCBs may be the main causal agent in the toxicity studies (p D-78) However the TIE was not a definitive study and was not designed to provide an independent evaluation of effects and the results of the TIE are inconclusive showing only that non-polar organic chemicals were likely responsible for the observed toxicity As a result while the results of the TIE provide some evidence as to the degree to which observed effects can be linked to PCBs rather than other COPCs the TIE study should be removed as a separate line of evidence

314 Need to Acknowledge Additional Uncertainties There are a number of uncertainties associated with the benthic invertebrate studies Some of these are acknowledged in the text (pp D-95 through D-98) but other critical uncertainties are not The text should be revised to acknowledge the following uncertainties

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Lack of concordance between benthic community and sediment toxicity study results At the four stations for which there are both sediment toxicity test data and benthic community data those results are contradictory The sediment toxicity tests show a toxic response for most endpoints (especially at Stations 7 and 8) whereas the benthic community analyses do not (see Figure D4-15) GE recommends that the ERA be revised to discuss this point in the uncertainty section and also to carry this through to the conclusions in terms of the ability to extrapolate the potential for adverse effects to downstream locations

Inconsistent patterns oftPCB concentrations in sediment and tissues The ERA likewise does not discuss the fact that the median tPCB concentrations in sediments and those in tissue are not consistent (eg elevated tPCB concentrations in sediments were not co-located with those in tissue) (compare Figure 33-3 on p 3-18 with Figure 33-6 on p 3-22) These inconsistencies raise questions regarding the reliability of using median sediment concentrations as a measure of exposure for benthic invertebrates They also limit the usefulness of the biota sediment accumulation factors (BSAFs) which range from 08 to 61 (p D-32) in predicting tissue levels from sediment concentrations These inconsistencies should be acknowledged in the discussion of tissue chemistry (Section 335 pp 3-21 and 3-23) and the implications relative to estimating exposure should be addressed in the uncertainty section

Calculation of LC$o and ICso values The toxicity test endpoints presented in Tables D4-1 through D4-3 based on statistical analyses have a number of significant uncertainties Specifically uncertainties are associated with the results in which (a) the chi-square value exceeds the critical value in the derivation of LCjos and LC2os (20 out of 54 endpoints) (b) visual observations rather than the probit analyses were used because the model did not converge (2 out of 54 endpoints) and (c) there was an interrupted dose-response (9 of 54 endpoints) These difficulties with the statistical analyses are indicative of inconsistencies in the dose-response relationships that result in uncertainty surrounding the threshold values These uncertainties should be addressed (Tables D4-1 - D4-3) In addition no explanation is provided for why the highest dose (772 mgkg) for H azteca 48-h survival is excluded from the effects threshold analysis (Table D4-1) Additional information should be included regarding its exclusion or the analyses should be redone using the results of this treatment

Use of single samples to characterize sediment in used in bioassays A discussion of the uncertainty associated with determining exposure values of sediment composites used in toxicity testing based on a single chemistry sample should be provided (p D-17) Alternatively if multiple samples were used to evaluate potential heterogeneity in these composites to confirm that sediment was completely mixed then those data should be provided

315 Need for Additional Clarification and Information This section describes a number of issues for which the next draft of the ERA should provide clarification or additional data or analyses

Tissue effects thresholds from the literature The ERA states that the literature review was focused on Aroclor 1260 and 1254 (p 3-14) It should be revised to state that no effects thresholds were found based on studies with Aroclor 1260 and that only studies of tPCBs Aroclor 1254 and Clophen A50 were used to derive these thresholds The figures summarizing the literature effects thresholds should also be revised to indicate which study is associated with the effects reported (eg in Figure 44-13)

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and to indicate that studies with Clophen A50 are included in the summary In addition congenershyspecific studies should be removed from the literature review (Table D3-5 and Attachment DI) as they are not appropriate surrogates for tPCB toxicity

Multi-dimensional scaling analysis The results of the multi-dimensional scaling (MDS) statistical analyses used to develop Figures D3-15 through D3-17 should be presented This will provide important information regarding the relative contribution of different factors in this multivariate analysis

Derivation of MATCs The ERA does not explain explicitly how the sediment MATC of 3 mgkg tPCB (p 3-72) used to assess the extent of risks downstream from the PSA was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should specifically document the derivation of the MATC value used

32 Amphibians In the assessment of amphibians the ERA derives toxicity thresholds (MATCs) of 1 mgkg in both tissue (based on the literature) and sediments (based on the results of EPAs wood frog study) As discussed below GE believes that neither of these thresholds is supported by the underlying studies and that they should be higher Moreover in evaluating the results of the wood frog study the ERA does not consider certain endpoints (metamorphosis and mortality) that have clear ecological relevance these endpoints should be included in the evaluation In addition as further discussed in these comments we urge EPA to (a) give lower weight to the results of the leopard frog study and explicitly recognize its use of external reference frogs (b) recognize additional specified uncertainties in the amphibian assessment (c) clarify or present additional data or analyses on certain issues (d) modify the extrapolation to reaches downstream of Woods Pond and (e) correct an error in the text1

321 Lack of Literature Support for a Toxicity Threshold of 1 mgkg tPCBs in Tissue The ERA specifies a toxicity threshold of 1 mgkg in tissue based on a review of the literature (pp 4shy75 E-96) The studies and results used in this review are summarized in Figures 44-13 and E3-37 However the two tPCB LOAELs (called LOELs in these figures) below 1 mgkg shown in these figures are not supported by the underlying study (Gutleb et al 2000) One of these effects levels for time to metamorphosis for the African clawed frog is based on exposure to PCB 126 although tissue chemistry was analyzed as tPCBs Comparing tPCB concentrations to effects levels from a study in which larvae were exposed to PCB 126 would substantially overstate tPCB toxicity and hence this effect level should not be used to evaluate potential tPCB effects The second LOAEL for the European common frog is 024 mgkg tPCBs (wet weight2) in tissue (based on exposure to Clophen A50) However at that concentration there was no adverse effect body weight in the exposed frogs was higher not lower than in the control frogs In fact there was no significant effect on body weight at the highest tissue concentration used in this study (112 mgkg tPCBs wet weight) Hence the latter

1 As noted in Section 1 EPA has also agreed to include the frog study sponsored by GE (Resetarits 2002) in the next draft of the ERA In addition GE has recently completed a study of leopard frog egg masses in the PSA and is providing a report on that study to EPA (ARCADIS 2003) That study should likewise be included in the next draft of the ERA

2 As converted from lipid weight in Attachment E2

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value should be reported as an unbounded NOAEL for that endpoint and the value reported as a LOAEL (024 mgkg) should be removed from these figures

Additional concerns associated with the summary of the literature effects are related to the interpretation of the frequency of occurrence of adverse effects (p 4-56 and E-81) First three LOAELs are cited for mortality based on a single experiment (Savage et al 2002) (Figure 4431 p 4shy57 and E3-37 p 60) By definition a LOAEL is the lowest concentration in an experiment for which there is a statistically significant difference relative to the control therefore only the LOAEL at approximately 6 mgkg from this study should be included in this figure When the erroneous LOAEL (Gutleb et al 2000) and the redundant LOAELs (Savage et al 2002) are removed the frequency of adverse effect analysis indicates that 4 out of 12 endpoints (for tPCBs) or 33 demonstrate adverse effects at concentrations greater than 1 mgkg and that in fact no adverse effects are observed below 6 mgkg

In addition the meaning of this frequency of adverse effects is not clear because there are substantive differences between the nature of effects observed For example the endpoints of reduced activity or swimming speed may or may not have the same severity of impact to an individual as increased mortality This distinction is lost in a simple evaluation of frequency of effects between different endpoints in various literature studies

Based on the above discussion the statement that [tjhere were six instances of adverse effects occurring between 1 and 10 mgkg (pp 4-56 and E-81) should be revised For tPCBs there are only three LOAELs (ie incidence of adverse effects) between 1 and 10 mgkg and all them are at or above 6 mgkg The text should be revised accordingly If the interpretation of these studies based on the frequency of adverse effects is retained that text should also be revised and uncertainties associated with direct comparisons of the different kinds of effects included in this analysis should be acknowledged

322 Lack of Support for a Sediment Toxicity Threshold of 1 mgkg Based on Wood Frog Study

The sediment toxicity threshold of 1 mgkg is apparently based primarily on an analysis of the results of EPAs wood frog study However the description of the results of that study states that [e]cologically significant adverse effects in late stage juvenile wood frogs occurred in the sediment tPCB concentration range of 10 to 60 mgkg although responses of lesser magnitude yet statistically significant were observed at 5 mgkg tPCB and lower (p 4-60) The latter statement (which may be the basis for the threshold) is apparently derived from the wood frog NOAELs and LOAELs presented in Table E4-2 However there are several problems or inconsistencies in the derivation of site-specific NOAELs and LOAELs presented in Table E4-2

bull In several instances the NOAELs and LOAELs do not coincide with sediment concentrations that are associated with the effects data For example the spatially weighted mean tPCB value of 136 mgkg is presented as either a NOAEL or LOAEL for all four endpoints in Table E4-2 However it appears that this value is associated with a vernal pool (46-VP-4 Table E2-8) that has no effects data associated with it (see Tables E3-5- E3-6 and E 310 - E3-11)

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bull It appears that the reference WML-1 has been excluded from the calculation of NOAELs and LOAELs for Phase III metamorphs because of zero response at this concentration(Table E4-2) This exclusion is not warranted While the text refers to the tissue tPCB concentration for reference location WML-1 in the Phase III of the wood frog study as anomalous (eg p 4-52) no problems with data quality are reported that would indicate that the organism did not in fact have a tissue burden of 44 mgkg tPCBs As a result responses associated with this exposure level should be considered to represent part of the range of effects and all analyses of exposure and effect should include this reference site Statistical comparisons with a zero value are commonly made using a value marginally greater than zero (eg 000001)

bull Concentration-response relationships for each endpoint were evaluated using both (1) the most synoptic chemistry value paired with each toxicity endpoint (also referred to as vernal pool sediment) and (2) a combined data set used to generate a spatially weighted surface average (pp 4shy16 mdash 4-17) Given the variability in sediment concentrations the samples used in the laboratory toxicity study should not be assumed to be equivalent to the surface weighted average The synoptic (ie vernal pool) data reflect the actual tPCB concentrations measured in sediments used in the laboratory exposures and should thus should be used for analyses of the Phase I wood frog study which was conducted in the laboratory The surface weighted averages should be used for the analysis of Phase II and Phase III studies in which larvae and metamorphs were exposed in the field as they encompass the range of concentrations to which the growing larvae and metamorphs might have been exposed to The NOAELs LOAELs and point estimates for effects concentrations (eg LC50 and LC20) (Table E4-2) should be revised accordingly

bull Table E4-2 states that the reference site had no malformed specimens (Phase II metamorphs percent malformed) In fact Table E3-11 indicates that reference site WML-3 had 29 malformations

Moreover the toxicity threshold for wood frogs was derived based only on endpoints that showed effects The ERA states that if no discern[i]ble differences in effect levels across treatments were observed (ie inadequate range in response variable) the effects endpoint was not considered in the detailed statistical evaluation (p E-90) As a result as discussed in the next section the lack of PCB-related effects for key endpoints (ie mortality and metamorphosis) were not considered in the derivation of the effects threshold Consideration of the results for those omitted endpoints shows further that the sediment MATC of 1 mgkg is too low

We also note that although Appendix E presents tissue-based HQs for leopard frogs and wood frogs (pp E-96 - E-98) Section 12 of the ERA presents only sediment-based HQs (Figures 122-1 and p 12shy7) Tissue concentrations provide a more direct measure of exposure than do sediment concentrations and hence the tissue-based rather than sediment-based HQs should be used in Section 12

323 Need to Consider Additional Relevant Endpoints in Wood Frog Study As noted above in evaluating the results of the wood frog study two endpoints with clear ecological relevance ~ metamorphosis and mortality -- were screened out of the formal concentration-response modeling due to a lack of discern[i]ble differences in effect levels across treatments (p E-90) However these two endpoints integrate other effects (ie the most serious effect of malformations would be reduced metamorphosis and increased mortality) and should be carried through the

concentration-response evaluation If no concentration-response curve can be derived because there were no effects then the highest dose should be treated as a NOAEL for these endpoints the LC50

should be expressed as gt highest dose and both mortality and metamorphosis should be considered subsequently as part of the lines-of-evidence evaluation

324 Evaluation of the Leopard Frog Study EPAs leopard frog study receives the same overall weight (moderatehigh) as its wood frog study in the weight-of evidence-evaluation (Table 45-4 p 4-69) Considering the significant problems with the leopard frog study as detailed in GEs comments on this study (BBL Sciences et al 2003a) it should be accorded a low weight

Moreover the text does not consistently acknowledge that reference frogs for the leopard frog study were obtained from a biological supply company For readers unfamiliar with the underlying study this could lead to misinterpretations of the results presented The text should be modified to clearly represent this aspect of the leopard frog study as well as additional qualifications as follows

bull The first time the study design of the leopard frog study is presented it should be clearly stated that no frogs or eggslarvae were found in the reference areas (p 4-13)

bull The text that describes comparisons between both the toxicity studies and the community evaluations and appropriately matched field references (p 4-27) should be revised to indicate that for the leopard frog study the field reference was limited to sediment not frogs collected from a reference pond

bull Although the text states that reference ponds were surveyed for eggs and larvae it does not indicate that in addition to no eggs or larvae being found at four of nine contaminated sites none were found at the reference sites (p 4-35)

bull Similarly the summary of female leopard frog reproductive fitness identifies all of the Housatonic River sites that were not gravid (did not have eggs mature enough for successful fertilization) (p 4shy30) It should also indicate that R2 (external reference) did not have any successful fertilization

325 Need to Acknowledge Additional Uncertainties While the ERA acknowledges some uncertainties associated with the amphibian studies (pp 4-70 4shy73 E-108-110) other critical uncertainties are not acknowledged For example there are uncertainties associated with the concentration-response analysis (eg ECsos ECaos) based on the poor fit of the data in the probit analysis Contrary to the statement that most endpoints followed a fairly smooth concentration-response (text box p 4-60) Table E4-2 indicates that only one of 11 of the ECsos presented (ie Phase III metamorph percent malformed based on comparisons with the lowest vernal pool sediment tPCB concentration) appears to be appropriately described by the probit analysis The other ECsos were described as (a) outside data range confidence limits increase (111) (b) probit model had poor fit to data confidence limits increase (111) (c) calculated with linear interpolation no confidence limits can be calculated (311) and (d) based on visual inspection of data (511) These uncertainties should be recognized

326 Need for Additional Information There are a number of issues on which we urge EPA to provide additional information in the next draft of the ERA

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Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

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Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

The ERA recognizes that the Rest of River includes areas of the Housatonic River and its sediments and floodplain (except ActualPotential Lawns) in which contaminants migrating from the GE facility are located (p 1-2) However it includes as COPCs a number of non-PCB constituents that are or may not be related to releases from the GE facility These include for various media numerous polycyclic aromatic hydrocarbons (PAHs) and other semi-volatile organic compounds (SVOCs) dioxins and furans several metals and (for fish) certain pesticides (Tables 24-2 through 24-5) There are multiple potential sources of these constituents in the Rest of River area not just releases from the GE facility

To avoid any confusion the ERA should make clear in its discussions of the COPCs (Sections 231 and 243) that while several COPCs other than PCBs have been selected for the ERA there are multiple potential sources of these constituents and hence there is no evidence demonstrating that the occurrence of these COPCs in the Rest of River area is necessarily derived from releases attributable to GE

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3 Specific Comments

31 Benthic Invertebrates In its assessment of benthic invertebrates the ERA derives toxicity thresholds (MATCs) of 3 mgkg tPCB in both tissue (based on the literature) and sediments (based on the results of toxicity and benthic community studies) GE believes that these thresholds should be reevaluated As discussed in this section GE urges EPA to make the following changes to the ERAs assessment of benthic invertebrates (a) use a different data set to calculate sediment-based toxicity thresholds (b) take adequate account of sediment grain size in interpreting the benthic community and toxicity test results (c) reduce the emphasis on Sediment Quality Values and the Toxicity Identification Evaluation (TIE) results (d) recognize a number of additional specified uncertainties and (e) clarify or provide additional information on certain issues

311 Concentration-Response Analysis to Derive Sediment Toxicity Thresholds The ERA concludes that the toxicity studies showed ecologically significant effects at sediment tPCB concentrations of 3 mgkg or higher (pp 3-71 D-98) the proposed MATC for sediment This proposed toxicity threshold is apparently based on LCso and ICso values from laboratory studies that were calculated based on the median values of multiple grab samples (p D-10) (some of which were collected independently of the laboratory bioassays) rather than based on measured concentrations of PCBs in sediments actually used in these bioassays The use of these unrelated data as a basis for establishing exposure levels in laboratory bioassays is of concern given that PCB concentrations in sediments of the Housatonic River can vary by orders of magnitude over very small spatial and temporal scales (pp D-26 to D-28) The rationale given for this method is that combining data from sampling events that are approximately (but not exactly) synoptic with the effects data more accurately portrays the COC concentrations at each station (p D-27) This approach may provide an indication of PCB concentrations in the vicinity of a station over time but it does not provide a better measure of PCB concentrations in the specific composites used in the bioassays than would a direct measure of PCBs in the sediments used in the bioassays For some stations concentrations measured directly from the composites are in fact substantially different than those derived from other collection efforts (Figures D3-1 through D3-5 Stations 7 and 8A) resulting in variability which likely substantially affects the exposure-response analyses and resulting LCsos and ICsoS Because of this variability it is important that effects levels for bioassay tests be calculated from the data that represent the concentrations to which these organisms were actually exposed

GE recommends that the ERA be revised to calculate the No Observed Adverse Effect Levels (NOAELs) Lowest Observed Adverse Effect Levels (LOAELs) and LCsoICso values for the laboratory bioassays (Tables D4-2 and D4-3) based on the synoptic values derived directly from the composite samples for the laboratory bioassays because these values best represent the exposures to the test organisms The LCao and IC20 values should also be revised in a similar manner as should the linear regression models (Table D4-4 Figure D4-5)

312 Effects of Grain Size on Study Interpretation Grain size is a significant variable that can impact both benthic community structure and the endpoints evaluated in the laboratory toxicity studies However in several instances the ERA does not adequately consider the effects of grain size in interpreting the study results

The ERA states that the benthic community data indicated that five of the six stations with median tPCB concentrations above 5 mgkg had significant benthic community alteration (p D-98) Those same five stations had coarse-grained sediments (see Figures D4-6 and D4-7) The one fine-grained station with median tPCB concentrations greater than 5 mgkg (Station 8) had higher species richness and abundance than the coarse-grained stations and was not significantly different from the reference stations (see Figures D4-6 D4-7 and D4-15) Benthic invertebrates tend to be the least diverse and the least abundant in sand likely due to its instability (Ward 1992 Minshall 1984 Allan 1995) Thus even in the absence of PCBs the diversity and abundance of invertebrates would be expected to be lower at the coarse-grained stations In these circumstances it is at least equally likely that grain size rather than PCB concentration explains the spatial variations in benthic community structure As a result the statements throughout the ERA regarding the high level of confidence in the conclusion that benthic invertebrates in the Housatonic River experience unacceptable risks due to tPCBs (eg p 12-55) are not be supported Those statements should be revised to recognize the confounding impacts and uncertainty associated with grain size effects and to note that as a result the benthic community data do not provide conclusive evidence of tPCB effects on changes in community structure

Similar concerns apply to the bioassay test The reference stations used in the bioassay test (Al and A3) are coarse-grained (Figure D2-2) whereas the treatment stations showing the highest levels of response (Stations 7 8 and 8A) are fine-grained Statistical analyses and the weight of evidence evaluation are based on comparisons made between Housatonic River sediment stations and references regardless of grain size (Table D3-4 and Figure D4-15) The uncertainty associated with comparing the toxicity of fine-grained stations to coarse-grained reference treatments should be acknowledged

313 Use of Sediment Quality Values and Toxicity Identification Evaluation in the Weight-of-Evidence

The ERA also relies on published Sediment Quality Values (SQVs) to support a sediment toxicity threshold value of 3 to 5 mgkg (pp 3-71 D-98) SQVs are generic in nature and therefore are primarily appropriate in screening-level ERAs when no site-specific data are available (see eg Long et al 1995) Given the availability of substantial site-specific data the generic SQVs should not be used at all or at a minimum given very low weight and the references to them should be removed from the conclusions

The ERA also gives moderate weight to the results of the Toxicity Identification Evaluation (TIE) (Table D4-5) The ERA concludes from this Phase I TIE that PCBs may be the main causal agent in the toxicity studies (p D-78) However the TIE was not a definitive study and was not designed to provide an independent evaluation of effects and the results of the TIE are inconclusive showing only that non-polar organic chemicals were likely responsible for the observed toxicity As a result while the results of the TIE provide some evidence as to the degree to which observed effects can be linked to PCBs rather than other COPCs the TIE study should be removed as a separate line of evidence

314 Need to Acknowledge Additional Uncertainties There are a number of uncertainties associated with the benthic invertebrate studies Some of these are acknowledged in the text (pp D-95 through D-98) but other critical uncertainties are not The text should be revised to acknowledge the following uncertainties

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Lack of concordance between benthic community and sediment toxicity study results At the four stations for which there are both sediment toxicity test data and benthic community data those results are contradictory The sediment toxicity tests show a toxic response for most endpoints (especially at Stations 7 and 8) whereas the benthic community analyses do not (see Figure D4-15) GE recommends that the ERA be revised to discuss this point in the uncertainty section and also to carry this through to the conclusions in terms of the ability to extrapolate the potential for adverse effects to downstream locations

Inconsistent patterns oftPCB concentrations in sediment and tissues The ERA likewise does not discuss the fact that the median tPCB concentrations in sediments and those in tissue are not consistent (eg elevated tPCB concentrations in sediments were not co-located with those in tissue) (compare Figure 33-3 on p 3-18 with Figure 33-6 on p 3-22) These inconsistencies raise questions regarding the reliability of using median sediment concentrations as a measure of exposure for benthic invertebrates They also limit the usefulness of the biota sediment accumulation factors (BSAFs) which range from 08 to 61 (p D-32) in predicting tissue levels from sediment concentrations These inconsistencies should be acknowledged in the discussion of tissue chemistry (Section 335 pp 3-21 and 3-23) and the implications relative to estimating exposure should be addressed in the uncertainty section

Calculation of LC$o and ICso values The toxicity test endpoints presented in Tables D4-1 through D4-3 based on statistical analyses have a number of significant uncertainties Specifically uncertainties are associated with the results in which (a) the chi-square value exceeds the critical value in the derivation of LCjos and LC2os (20 out of 54 endpoints) (b) visual observations rather than the probit analyses were used because the model did not converge (2 out of 54 endpoints) and (c) there was an interrupted dose-response (9 of 54 endpoints) These difficulties with the statistical analyses are indicative of inconsistencies in the dose-response relationships that result in uncertainty surrounding the threshold values These uncertainties should be addressed (Tables D4-1 - D4-3) In addition no explanation is provided for why the highest dose (772 mgkg) for H azteca 48-h survival is excluded from the effects threshold analysis (Table D4-1) Additional information should be included regarding its exclusion or the analyses should be redone using the results of this treatment

Use of single samples to characterize sediment in used in bioassays A discussion of the uncertainty associated with determining exposure values of sediment composites used in toxicity testing based on a single chemistry sample should be provided (p D-17) Alternatively if multiple samples were used to evaluate potential heterogeneity in these composites to confirm that sediment was completely mixed then those data should be provided

315 Need for Additional Clarification and Information This section describes a number of issues for which the next draft of the ERA should provide clarification or additional data or analyses

Tissue effects thresholds from the literature The ERA states that the literature review was focused on Aroclor 1260 and 1254 (p 3-14) It should be revised to state that no effects thresholds were found based on studies with Aroclor 1260 and that only studies of tPCBs Aroclor 1254 and Clophen A50 were used to derive these thresholds The figures summarizing the literature effects thresholds should also be revised to indicate which study is associated with the effects reported (eg in Figure 44-13)

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and to indicate that studies with Clophen A50 are included in the summary In addition congenershyspecific studies should be removed from the literature review (Table D3-5 and Attachment DI) as they are not appropriate surrogates for tPCB toxicity

Multi-dimensional scaling analysis The results of the multi-dimensional scaling (MDS) statistical analyses used to develop Figures D3-15 through D3-17 should be presented This will provide important information regarding the relative contribution of different factors in this multivariate analysis

Derivation of MATCs The ERA does not explain explicitly how the sediment MATC of 3 mgkg tPCB (p 3-72) used to assess the extent of risks downstream from the PSA was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should specifically document the derivation of the MATC value used

32 Amphibians In the assessment of amphibians the ERA derives toxicity thresholds (MATCs) of 1 mgkg in both tissue (based on the literature) and sediments (based on the results of EPAs wood frog study) As discussed below GE believes that neither of these thresholds is supported by the underlying studies and that they should be higher Moreover in evaluating the results of the wood frog study the ERA does not consider certain endpoints (metamorphosis and mortality) that have clear ecological relevance these endpoints should be included in the evaluation In addition as further discussed in these comments we urge EPA to (a) give lower weight to the results of the leopard frog study and explicitly recognize its use of external reference frogs (b) recognize additional specified uncertainties in the amphibian assessment (c) clarify or present additional data or analyses on certain issues (d) modify the extrapolation to reaches downstream of Woods Pond and (e) correct an error in the text1

321 Lack of Literature Support for a Toxicity Threshold of 1 mgkg tPCBs in Tissue The ERA specifies a toxicity threshold of 1 mgkg in tissue based on a review of the literature (pp 4shy75 E-96) The studies and results used in this review are summarized in Figures 44-13 and E3-37 However the two tPCB LOAELs (called LOELs in these figures) below 1 mgkg shown in these figures are not supported by the underlying study (Gutleb et al 2000) One of these effects levels for time to metamorphosis for the African clawed frog is based on exposure to PCB 126 although tissue chemistry was analyzed as tPCBs Comparing tPCB concentrations to effects levels from a study in which larvae were exposed to PCB 126 would substantially overstate tPCB toxicity and hence this effect level should not be used to evaluate potential tPCB effects The second LOAEL for the European common frog is 024 mgkg tPCBs (wet weight2) in tissue (based on exposure to Clophen A50) However at that concentration there was no adverse effect body weight in the exposed frogs was higher not lower than in the control frogs In fact there was no significant effect on body weight at the highest tissue concentration used in this study (112 mgkg tPCBs wet weight) Hence the latter

1 As noted in Section 1 EPA has also agreed to include the frog study sponsored by GE (Resetarits 2002) in the next draft of the ERA In addition GE has recently completed a study of leopard frog egg masses in the PSA and is providing a report on that study to EPA (ARCADIS 2003) That study should likewise be included in the next draft of the ERA

2 As converted from lipid weight in Attachment E2

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value should be reported as an unbounded NOAEL for that endpoint and the value reported as a LOAEL (024 mgkg) should be removed from these figures

Additional concerns associated with the summary of the literature effects are related to the interpretation of the frequency of occurrence of adverse effects (p 4-56 and E-81) First three LOAELs are cited for mortality based on a single experiment (Savage et al 2002) (Figure 4431 p 4shy57 and E3-37 p 60) By definition a LOAEL is the lowest concentration in an experiment for which there is a statistically significant difference relative to the control therefore only the LOAEL at approximately 6 mgkg from this study should be included in this figure When the erroneous LOAEL (Gutleb et al 2000) and the redundant LOAELs (Savage et al 2002) are removed the frequency of adverse effect analysis indicates that 4 out of 12 endpoints (for tPCBs) or 33 demonstrate adverse effects at concentrations greater than 1 mgkg and that in fact no adverse effects are observed below 6 mgkg

In addition the meaning of this frequency of adverse effects is not clear because there are substantive differences between the nature of effects observed For example the endpoints of reduced activity or swimming speed may or may not have the same severity of impact to an individual as increased mortality This distinction is lost in a simple evaluation of frequency of effects between different endpoints in various literature studies

Based on the above discussion the statement that [tjhere were six instances of adverse effects occurring between 1 and 10 mgkg (pp 4-56 and E-81) should be revised For tPCBs there are only three LOAELs (ie incidence of adverse effects) between 1 and 10 mgkg and all them are at or above 6 mgkg The text should be revised accordingly If the interpretation of these studies based on the frequency of adverse effects is retained that text should also be revised and uncertainties associated with direct comparisons of the different kinds of effects included in this analysis should be acknowledged

322 Lack of Support for a Sediment Toxicity Threshold of 1 mgkg Based on Wood Frog Study

The sediment toxicity threshold of 1 mgkg is apparently based primarily on an analysis of the results of EPAs wood frog study However the description of the results of that study states that [e]cologically significant adverse effects in late stage juvenile wood frogs occurred in the sediment tPCB concentration range of 10 to 60 mgkg although responses of lesser magnitude yet statistically significant were observed at 5 mgkg tPCB and lower (p 4-60) The latter statement (which may be the basis for the threshold) is apparently derived from the wood frog NOAELs and LOAELs presented in Table E4-2 However there are several problems or inconsistencies in the derivation of site-specific NOAELs and LOAELs presented in Table E4-2

bull In several instances the NOAELs and LOAELs do not coincide with sediment concentrations that are associated with the effects data For example the spatially weighted mean tPCB value of 136 mgkg is presented as either a NOAEL or LOAEL for all four endpoints in Table E4-2 However it appears that this value is associated with a vernal pool (46-VP-4 Table E2-8) that has no effects data associated with it (see Tables E3-5- E3-6 and E 310 - E3-11)

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bull It appears that the reference WML-1 has been excluded from the calculation of NOAELs and LOAELs for Phase III metamorphs because of zero response at this concentration(Table E4-2) This exclusion is not warranted While the text refers to the tissue tPCB concentration for reference location WML-1 in the Phase III of the wood frog study as anomalous (eg p 4-52) no problems with data quality are reported that would indicate that the organism did not in fact have a tissue burden of 44 mgkg tPCBs As a result responses associated with this exposure level should be considered to represent part of the range of effects and all analyses of exposure and effect should include this reference site Statistical comparisons with a zero value are commonly made using a value marginally greater than zero (eg 000001)

bull Concentration-response relationships for each endpoint were evaluated using both (1) the most synoptic chemistry value paired with each toxicity endpoint (also referred to as vernal pool sediment) and (2) a combined data set used to generate a spatially weighted surface average (pp 4shy16 mdash 4-17) Given the variability in sediment concentrations the samples used in the laboratory toxicity study should not be assumed to be equivalent to the surface weighted average The synoptic (ie vernal pool) data reflect the actual tPCB concentrations measured in sediments used in the laboratory exposures and should thus should be used for analyses of the Phase I wood frog study which was conducted in the laboratory The surface weighted averages should be used for the analysis of Phase II and Phase III studies in which larvae and metamorphs were exposed in the field as they encompass the range of concentrations to which the growing larvae and metamorphs might have been exposed to The NOAELs LOAELs and point estimates for effects concentrations (eg LC50 and LC20) (Table E4-2) should be revised accordingly

bull Table E4-2 states that the reference site had no malformed specimens (Phase II metamorphs percent malformed) In fact Table E3-11 indicates that reference site WML-3 had 29 malformations

Moreover the toxicity threshold for wood frogs was derived based only on endpoints that showed effects The ERA states that if no discern[i]ble differences in effect levels across treatments were observed (ie inadequate range in response variable) the effects endpoint was not considered in the detailed statistical evaluation (p E-90) As a result as discussed in the next section the lack of PCB-related effects for key endpoints (ie mortality and metamorphosis) were not considered in the derivation of the effects threshold Consideration of the results for those omitted endpoints shows further that the sediment MATC of 1 mgkg is too low

We also note that although Appendix E presents tissue-based HQs for leopard frogs and wood frogs (pp E-96 - E-98) Section 12 of the ERA presents only sediment-based HQs (Figures 122-1 and p 12shy7) Tissue concentrations provide a more direct measure of exposure than do sediment concentrations and hence the tissue-based rather than sediment-based HQs should be used in Section 12

323 Need to Consider Additional Relevant Endpoints in Wood Frog Study As noted above in evaluating the results of the wood frog study two endpoints with clear ecological relevance ~ metamorphosis and mortality -- were screened out of the formal concentration-response modeling due to a lack of discern[i]ble differences in effect levels across treatments (p E-90) However these two endpoints integrate other effects (ie the most serious effect of malformations would be reduced metamorphosis and increased mortality) and should be carried through the

concentration-response evaluation If no concentration-response curve can be derived because there were no effects then the highest dose should be treated as a NOAEL for these endpoints the LC50

should be expressed as gt highest dose and both mortality and metamorphosis should be considered subsequently as part of the lines-of-evidence evaluation

324 Evaluation of the Leopard Frog Study EPAs leopard frog study receives the same overall weight (moderatehigh) as its wood frog study in the weight-of evidence-evaluation (Table 45-4 p 4-69) Considering the significant problems with the leopard frog study as detailed in GEs comments on this study (BBL Sciences et al 2003a) it should be accorded a low weight

Moreover the text does not consistently acknowledge that reference frogs for the leopard frog study were obtained from a biological supply company For readers unfamiliar with the underlying study this could lead to misinterpretations of the results presented The text should be modified to clearly represent this aspect of the leopard frog study as well as additional qualifications as follows

bull The first time the study design of the leopard frog study is presented it should be clearly stated that no frogs or eggslarvae were found in the reference areas (p 4-13)

bull The text that describes comparisons between both the toxicity studies and the community evaluations and appropriately matched field references (p 4-27) should be revised to indicate that for the leopard frog study the field reference was limited to sediment not frogs collected from a reference pond

bull Although the text states that reference ponds were surveyed for eggs and larvae it does not indicate that in addition to no eggs or larvae being found at four of nine contaminated sites none were found at the reference sites (p 4-35)

bull Similarly the summary of female leopard frog reproductive fitness identifies all of the Housatonic River sites that were not gravid (did not have eggs mature enough for successful fertilization) (p 4shy30) It should also indicate that R2 (external reference) did not have any successful fertilization

325 Need to Acknowledge Additional Uncertainties While the ERA acknowledges some uncertainties associated with the amphibian studies (pp 4-70 4shy73 E-108-110) other critical uncertainties are not acknowledged For example there are uncertainties associated with the concentration-response analysis (eg ECsos ECaos) based on the poor fit of the data in the probit analysis Contrary to the statement that most endpoints followed a fairly smooth concentration-response (text box p 4-60) Table E4-2 indicates that only one of 11 of the ECsos presented (ie Phase III metamorph percent malformed based on comparisons with the lowest vernal pool sediment tPCB concentration) appears to be appropriately described by the probit analysis The other ECsos were described as (a) outside data range confidence limits increase (111) (b) probit model had poor fit to data confidence limits increase (111) (c) calculated with linear interpolation no confidence limits can be calculated (311) and (d) based on visual inspection of data (511) These uncertainties should be recognized

326 Need for Additional Information There are a number of issues on which we urge EPA to provide additional information in the next draft of the ERA

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Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

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Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

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3 Specific Comments

31 Benthic Invertebrates In its assessment of benthic invertebrates the ERA derives toxicity thresholds (MATCs) of 3 mgkg tPCB in both tissue (based on the literature) and sediments (based on the results of toxicity and benthic community studies) GE believes that these thresholds should be reevaluated As discussed in this section GE urges EPA to make the following changes to the ERAs assessment of benthic invertebrates (a) use a different data set to calculate sediment-based toxicity thresholds (b) take adequate account of sediment grain size in interpreting the benthic community and toxicity test results (c) reduce the emphasis on Sediment Quality Values and the Toxicity Identification Evaluation (TIE) results (d) recognize a number of additional specified uncertainties and (e) clarify or provide additional information on certain issues

311 Concentration-Response Analysis to Derive Sediment Toxicity Thresholds The ERA concludes that the toxicity studies showed ecologically significant effects at sediment tPCB concentrations of 3 mgkg or higher (pp 3-71 D-98) the proposed MATC for sediment This proposed toxicity threshold is apparently based on LCso and ICso values from laboratory studies that were calculated based on the median values of multiple grab samples (p D-10) (some of which were collected independently of the laboratory bioassays) rather than based on measured concentrations of PCBs in sediments actually used in these bioassays The use of these unrelated data as a basis for establishing exposure levels in laboratory bioassays is of concern given that PCB concentrations in sediments of the Housatonic River can vary by orders of magnitude over very small spatial and temporal scales (pp D-26 to D-28) The rationale given for this method is that combining data from sampling events that are approximately (but not exactly) synoptic with the effects data more accurately portrays the COC concentrations at each station (p D-27) This approach may provide an indication of PCB concentrations in the vicinity of a station over time but it does not provide a better measure of PCB concentrations in the specific composites used in the bioassays than would a direct measure of PCBs in the sediments used in the bioassays For some stations concentrations measured directly from the composites are in fact substantially different than those derived from other collection efforts (Figures D3-1 through D3-5 Stations 7 and 8A) resulting in variability which likely substantially affects the exposure-response analyses and resulting LCsos and ICsoS Because of this variability it is important that effects levels for bioassay tests be calculated from the data that represent the concentrations to which these organisms were actually exposed

GE recommends that the ERA be revised to calculate the No Observed Adverse Effect Levels (NOAELs) Lowest Observed Adverse Effect Levels (LOAELs) and LCsoICso values for the laboratory bioassays (Tables D4-2 and D4-3) based on the synoptic values derived directly from the composite samples for the laboratory bioassays because these values best represent the exposures to the test organisms The LCao and IC20 values should also be revised in a similar manner as should the linear regression models (Table D4-4 Figure D4-5)

312 Effects of Grain Size on Study Interpretation Grain size is a significant variable that can impact both benthic community structure and the endpoints evaluated in the laboratory toxicity studies However in several instances the ERA does not adequately consider the effects of grain size in interpreting the study results

The ERA states that the benthic community data indicated that five of the six stations with median tPCB concentrations above 5 mgkg had significant benthic community alteration (p D-98) Those same five stations had coarse-grained sediments (see Figures D4-6 and D4-7) The one fine-grained station with median tPCB concentrations greater than 5 mgkg (Station 8) had higher species richness and abundance than the coarse-grained stations and was not significantly different from the reference stations (see Figures D4-6 D4-7 and D4-15) Benthic invertebrates tend to be the least diverse and the least abundant in sand likely due to its instability (Ward 1992 Minshall 1984 Allan 1995) Thus even in the absence of PCBs the diversity and abundance of invertebrates would be expected to be lower at the coarse-grained stations In these circumstances it is at least equally likely that grain size rather than PCB concentration explains the spatial variations in benthic community structure As a result the statements throughout the ERA regarding the high level of confidence in the conclusion that benthic invertebrates in the Housatonic River experience unacceptable risks due to tPCBs (eg p 12-55) are not be supported Those statements should be revised to recognize the confounding impacts and uncertainty associated with grain size effects and to note that as a result the benthic community data do not provide conclusive evidence of tPCB effects on changes in community structure

Similar concerns apply to the bioassay test The reference stations used in the bioassay test (Al and A3) are coarse-grained (Figure D2-2) whereas the treatment stations showing the highest levels of response (Stations 7 8 and 8A) are fine-grained Statistical analyses and the weight of evidence evaluation are based on comparisons made between Housatonic River sediment stations and references regardless of grain size (Table D3-4 and Figure D4-15) The uncertainty associated with comparing the toxicity of fine-grained stations to coarse-grained reference treatments should be acknowledged

313 Use of Sediment Quality Values and Toxicity Identification Evaluation in the Weight-of-Evidence

The ERA also relies on published Sediment Quality Values (SQVs) to support a sediment toxicity threshold value of 3 to 5 mgkg (pp 3-71 D-98) SQVs are generic in nature and therefore are primarily appropriate in screening-level ERAs when no site-specific data are available (see eg Long et al 1995) Given the availability of substantial site-specific data the generic SQVs should not be used at all or at a minimum given very low weight and the references to them should be removed from the conclusions

The ERA also gives moderate weight to the results of the Toxicity Identification Evaluation (TIE) (Table D4-5) The ERA concludes from this Phase I TIE that PCBs may be the main causal agent in the toxicity studies (p D-78) However the TIE was not a definitive study and was not designed to provide an independent evaluation of effects and the results of the TIE are inconclusive showing only that non-polar organic chemicals were likely responsible for the observed toxicity As a result while the results of the TIE provide some evidence as to the degree to which observed effects can be linked to PCBs rather than other COPCs the TIE study should be removed as a separate line of evidence

314 Need to Acknowledge Additional Uncertainties There are a number of uncertainties associated with the benthic invertebrate studies Some of these are acknowledged in the text (pp D-95 through D-98) but other critical uncertainties are not The text should be revised to acknowledge the following uncertainties

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Lack of concordance between benthic community and sediment toxicity study results At the four stations for which there are both sediment toxicity test data and benthic community data those results are contradictory The sediment toxicity tests show a toxic response for most endpoints (especially at Stations 7 and 8) whereas the benthic community analyses do not (see Figure D4-15) GE recommends that the ERA be revised to discuss this point in the uncertainty section and also to carry this through to the conclusions in terms of the ability to extrapolate the potential for adverse effects to downstream locations

Inconsistent patterns oftPCB concentrations in sediment and tissues The ERA likewise does not discuss the fact that the median tPCB concentrations in sediments and those in tissue are not consistent (eg elevated tPCB concentrations in sediments were not co-located with those in tissue) (compare Figure 33-3 on p 3-18 with Figure 33-6 on p 3-22) These inconsistencies raise questions regarding the reliability of using median sediment concentrations as a measure of exposure for benthic invertebrates They also limit the usefulness of the biota sediment accumulation factors (BSAFs) which range from 08 to 61 (p D-32) in predicting tissue levels from sediment concentrations These inconsistencies should be acknowledged in the discussion of tissue chemistry (Section 335 pp 3-21 and 3-23) and the implications relative to estimating exposure should be addressed in the uncertainty section

Calculation of LC$o and ICso values The toxicity test endpoints presented in Tables D4-1 through D4-3 based on statistical analyses have a number of significant uncertainties Specifically uncertainties are associated with the results in which (a) the chi-square value exceeds the critical value in the derivation of LCjos and LC2os (20 out of 54 endpoints) (b) visual observations rather than the probit analyses were used because the model did not converge (2 out of 54 endpoints) and (c) there was an interrupted dose-response (9 of 54 endpoints) These difficulties with the statistical analyses are indicative of inconsistencies in the dose-response relationships that result in uncertainty surrounding the threshold values These uncertainties should be addressed (Tables D4-1 - D4-3) In addition no explanation is provided for why the highest dose (772 mgkg) for H azteca 48-h survival is excluded from the effects threshold analysis (Table D4-1) Additional information should be included regarding its exclusion or the analyses should be redone using the results of this treatment

Use of single samples to characterize sediment in used in bioassays A discussion of the uncertainty associated with determining exposure values of sediment composites used in toxicity testing based on a single chemistry sample should be provided (p D-17) Alternatively if multiple samples were used to evaluate potential heterogeneity in these composites to confirm that sediment was completely mixed then those data should be provided

315 Need for Additional Clarification and Information This section describes a number of issues for which the next draft of the ERA should provide clarification or additional data or analyses

Tissue effects thresholds from the literature The ERA states that the literature review was focused on Aroclor 1260 and 1254 (p 3-14) It should be revised to state that no effects thresholds were found based on studies with Aroclor 1260 and that only studies of tPCBs Aroclor 1254 and Clophen A50 were used to derive these thresholds The figures summarizing the literature effects thresholds should also be revised to indicate which study is associated with the effects reported (eg in Figure 44-13)

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and to indicate that studies with Clophen A50 are included in the summary In addition congenershyspecific studies should be removed from the literature review (Table D3-5 and Attachment DI) as they are not appropriate surrogates for tPCB toxicity

Multi-dimensional scaling analysis The results of the multi-dimensional scaling (MDS) statistical analyses used to develop Figures D3-15 through D3-17 should be presented This will provide important information regarding the relative contribution of different factors in this multivariate analysis

Derivation of MATCs The ERA does not explain explicitly how the sediment MATC of 3 mgkg tPCB (p 3-72) used to assess the extent of risks downstream from the PSA was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should specifically document the derivation of the MATC value used

32 Amphibians In the assessment of amphibians the ERA derives toxicity thresholds (MATCs) of 1 mgkg in both tissue (based on the literature) and sediments (based on the results of EPAs wood frog study) As discussed below GE believes that neither of these thresholds is supported by the underlying studies and that they should be higher Moreover in evaluating the results of the wood frog study the ERA does not consider certain endpoints (metamorphosis and mortality) that have clear ecological relevance these endpoints should be included in the evaluation In addition as further discussed in these comments we urge EPA to (a) give lower weight to the results of the leopard frog study and explicitly recognize its use of external reference frogs (b) recognize additional specified uncertainties in the amphibian assessment (c) clarify or present additional data or analyses on certain issues (d) modify the extrapolation to reaches downstream of Woods Pond and (e) correct an error in the text1

321 Lack of Literature Support for a Toxicity Threshold of 1 mgkg tPCBs in Tissue The ERA specifies a toxicity threshold of 1 mgkg in tissue based on a review of the literature (pp 4shy75 E-96) The studies and results used in this review are summarized in Figures 44-13 and E3-37 However the two tPCB LOAELs (called LOELs in these figures) below 1 mgkg shown in these figures are not supported by the underlying study (Gutleb et al 2000) One of these effects levels for time to metamorphosis for the African clawed frog is based on exposure to PCB 126 although tissue chemistry was analyzed as tPCBs Comparing tPCB concentrations to effects levels from a study in which larvae were exposed to PCB 126 would substantially overstate tPCB toxicity and hence this effect level should not be used to evaluate potential tPCB effects The second LOAEL for the European common frog is 024 mgkg tPCBs (wet weight2) in tissue (based on exposure to Clophen A50) However at that concentration there was no adverse effect body weight in the exposed frogs was higher not lower than in the control frogs In fact there was no significant effect on body weight at the highest tissue concentration used in this study (112 mgkg tPCBs wet weight) Hence the latter

1 As noted in Section 1 EPA has also agreed to include the frog study sponsored by GE (Resetarits 2002) in the next draft of the ERA In addition GE has recently completed a study of leopard frog egg masses in the PSA and is providing a report on that study to EPA (ARCADIS 2003) That study should likewise be included in the next draft of the ERA

2 As converted from lipid weight in Attachment E2

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value should be reported as an unbounded NOAEL for that endpoint and the value reported as a LOAEL (024 mgkg) should be removed from these figures

Additional concerns associated with the summary of the literature effects are related to the interpretation of the frequency of occurrence of adverse effects (p 4-56 and E-81) First three LOAELs are cited for mortality based on a single experiment (Savage et al 2002) (Figure 4431 p 4shy57 and E3-37 p 60) By definition a LOAEL is the lowest concentration in an experiment for which there is a statistically significant difference relative to the control therefore only the LOAEL at approximately 6 mgkg from this study should be included in this figure When the erroneous LOAEL (Gutleb et al 2000) and the redundant LOAELs (Savage et al 2002) are removed the frequency of adverse effect analysis indicates that 4 out of 12 endpoints (for tPCBs) or 33 demonstrate adverse effects at concentrations greater than 1 mgkg and that in fact no adverse effects are observed below 6 mgkg

In addition the meaning of this frequency of adverse effects is not clear because there are substantive differences between the nature of effects observed For example the endpoints of reduced activity or swimming speed may or may not have the same severity of impact to an individual as increased mortality This distinction is lost in a simple evaluation of frequency of effects between different endpoints in various literature studies

Based on the above discussion the statement that [tjhere were six instances of adverse effects occurring between 1 and 10 mgkg (pp 4-56 and E-81) should be revised For tPCBs there are only three LOAELs (ie incidence of adverse effects) between 1 and 10 mgkg and all them are at or above 6 mgkg The text should be revised accordingly If the interpretation of these studies based on the frequency of adverse effects is retained that text should also be revised and uncertainties associated with direct comparisons of the different kinds of effects included in this analysis should be acknowledged

322 Lack of Support for a Sediment Toxicity Threshold of 1 mgkg Based on Wood Frog Study

The sediment toxicity threshold of 1 mgkg is apparently based primarily on an analysis of the results of EPAs wood frog study However the description of the results of that study states that [e]cologically significant adverse effects in late stage juvenile wood frogs occurred in the sediment tPCB concentration range of 10 to 60 mgkg although responses of lesser magnitude yet statistically significant were observed at 5 mgkg tPCB and lower (p 4-60) The latter statement (which may be the basis for the threshold) is apparently derived from the wood frog NOAELs and LOAELs presented in Table E4-2 However there are several problems or inconsistencies in the derivation of site-specific NOAELs and LOAELs presented in Table E4-2

bull In several instances the NOAELs and LOAELs do not coincide with sediment concentrations that are associated with the effects data For example the spatially weighted mean tPCB value of 136 mgkg is presented as either a NOAEL or LOAEL for all four endpoints in Table E4-2 However it appears that this value is associated with a vernal pool (46-VP-4 Table E2-8) that has no effects data associated with it (see Tables E3-5- E3-6 and E 310 - E3-11)

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bull It appears that the reference WML-1 has been excluded from the calculation of NOAELs and LOAELs for Phase III metamorphs because of zero response at this concentration(Table E4-2) This exclusion is not warranted While the text refers to the tissue tPCB concentration for reference location WML-1 in the Phase III of the wood frog study as anomalous (eg p 4-52) no problems with data quality are reported that would indicate that the organism did not in fact have a tissue burden of 44 mgkg tPCBs As a result responses associated with this exposure level should be considered to represent part of the range of effects and all analyses of exposure and effect should include this reference site Statistical comparisons with a zero value are commonly made using a value marginally greater than zero (eg 000001)

bull Concentration-response relationships for each endpoint were evaluated using both (1) the most synoptic chemistry value paired with each toxicity endpoint (also referred to as vernal pool sediment) and (2) a combined data set used to generate a spatially weighted surface average (pp 4shy16 mdash 4-17) Given the variability in sediment concentrations the samples used in the laboratory toxicity study should not be assumed to be equivalent to the surface weighted average The synoptic (ie vernal pool) data reflect the actual tPCB concentrations measured in sediments used in the laboratory exposures and should thus should be used for analyses of the Phase I wood frog study which was conducted in the laboratory The surface weighted averages should be used for the analysis of Phase II and Phase III studies in which larvae and metamorphs were exposed in the field as they encompass the range of concentrations to which the growing larvae and metamorphs might have been exposed to The NOAELs LOAELs and point estimates for effects concentrations (eg LC50 and LC20) (Table E4-2) should be revised accordingly

bull Table E4-2 states that the reference site had no malformed specimens (Phase II metamorphs percent malformed) In fact Table E3-11 indicates that reference site WML-3 had 29 malformations

Moreover the toxicity threshold for wood frogs was derived based only on endpoints that showed effects The ERA states that if no discern[i]ble differences in effect levels across treatments were observed (ie inadequate range in response variable) the effects endpoint was not considered in the detailed statistical evaluation (p E-90) As a result as discussed in the next section the lack of PCB-related effects for key endpoints (ie mortality and metamorphosis) were not considered in the derivation of the effects threshold Consideration of the results for those omitted endpoints shows further that the sediment MATC of 1 mgkg is too low

We also note that although Appendix E presents tissue-based HQs for leopard frogs and wood frogs (pp E-96 - E-98) Section 12 of the ERA presents only sediment-based HQs (Figures 122-1 and p 12shy7) Tissue concentrations provide a more direct measure of exposure than do sediment concentrations and hence the tissue-based rather than sediment-based HQs should be used in Section 12

323 Need to Consider Additional Relevant Endpoints in Wood Frog Study As noted above in evaluating the results of the wood frog study two endpoints with clear ecological relevance ~ metamorphosis and mortality -- were screened out of the formal concentration-response modeling due to a lack of discern[i]ble differences in effect levels across treatments (p E-90) However these two endpoints integrate other effects (ie the most serious effect of malformations would be reduced metamorphosis and increased mortality) and should be carried through the

concentration-response evaluation If no concentration-response curve can be derived because there were no effects then the highest dose should be treated as a NOAEL for these endpoints the LC50

should be expressed as gt highest dose and both mortality and metamorphosis should be considered subsequently as part of the lines-of-evidence evaluation

324 Evaluation of the Leopard Frog Study EPAs leopard frog study receives the same overall weight (moderatehigh) as its wood frog study in the weight-of evidence-evaluation (Table 45-4 p 4-69) Considering the significant problems with the leopard frog study as detailed in GEs comments on this study (BBL Sciences et al 2003a) it should be accorded a low weight

Moreover the text does not consistently acknowledge that reference frogs for the leopard frog study were obtained from a biological supply company For readers unfamiliar with the underlying study this could lead to misinterpretations of the results presented The text should be modified to clearly represent this aspect of the leopard frog study as well as additional qualifications as follows

bull The first time the study design of the leopard frog study is presented it should be clearly stated that no frogs or eggslarvae were found in the reference areas (p 4-13)

bull The text that describes comparisons between both the toxicity studies and the community evaluations and appropriately matched field references (p 4-27) should be revised to indicate that for the leopard frog study the field reference was limited to sediment not frogs collected from a reference pond

bull Although the text states that reference ponds were surveyed for eggs and larvae it does not indicate that in addition to no eggs or larvae being found at four of nine contaminated sites none were found at the reference sites (p 4-35)

bull Similarly the summary of female leopard frog reproductive fitness identifies all of the Housatonic River sites that were not gravid (did not have eggs mature enough for successful fertilization) (p 4shy30) It should also indicate that R2 (external reference) did not have any successful fertilization

325 Need to Acknowledge Additional Uncertainties While the ERA acknowledges some uncertainties associated with the amphibian studies (pp 4-70 4shy73 E-108-110) other critical uncertainties are not acknowledged For example there are uncertainties associated with the concentration-response analysis (eg ECsos ECaos) based on the poor fit of the data in the probit analysis Contrary to the statement that most endpoints followed a fairly smooth concentration-response (text box p 4-60) Table E4-2 indicates that only one of 11 of the ECsos presented (ie Phase III metamorph percent malformed based on comparisons with the lowest vernal pool sediment tPCB concentration) appears to be appropriately described by the probit analysis The other ECsos were described as (a) outside data range confidence limits increase (111) (b) probit model had poor fit to data confidence limits increase (111) (c) calculated with linear interpolation no confidence limits can be calculated (311) and (d) based on visual inspection of data (511) These uncertainties should be recognized

326 Need for Additional Information There are a number of issues on which we urge EPA to provide additional information in the next draft of the ERA

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Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

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Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

The ERA states that the benthic community data indicated that five of the six stations with median tPCB concentrations above 5 mgkg had significant benthic community alteration (p D-98) Those same five stations had coarse-grained sediments (see Figures D4-6 and D4-7) The one fine-grained station with median tPCB concentrations greater than 5 mgkg (Station 8) had higher species richness and abundance than the coarse-grained stations and was not significantly different from the reference stations (see Figures D4-6 D4-7 and D4-15) Benthic invertebrates tend to be the least diverse and the least abundant in sand likely due to its instability (Ward 1992 Minshall 1984 Allan 1995) Thus even in the absence of PCBs the diversity and abundance of invertebrates would be expected to be lower at the coarse-grained stations In these circumstances it is at least equally likely that grain size rather than PCB concentration explains the spatial variations in benthic community structure As a result the statements throughout the ERA regarding the high level of confidence in the conclusion that benthic invertebrates in the Housatonic River experience unacceptable risks due to tPCBs (eg p 12-55) are not be supported Those statements should be revised to recognize the confounding impacts and uncertainty associated with grain size effects and to note that as a result the benthic community data do not provide conclusive evidence of tPCB effects on changes in community structure

Similar concerns apply to the bioassay test The reference stations used in the bioassay test (Al and A3) are coarse-grained (Figure D2-2) whereas the treatment stations showing the highest levels of response (Stations 7 8 and 8A) are fine-grained Statistical analyses and the weight of evidence evaluation are based on comparisons made between Housatonic River sediment stations and references regardless of grain size (Table D3-4 and Figure D4-15) The uncertainty associated with comparing the toxicity of fine-grained stations to coarse-grained reference treatments should be acknowledged

313 Use of Sediment Quality Values and Toxicity Identification Evaluation in the Weight-of-Evidence

The ERA also relies on published Sediment Quality Values (SQVs) to support a sediment toxicity threshold value of 3 to 5 mgkg (pp 3-71 D-98) SQVs are generic in nature and therefore are primarily appropriate in screening-level ERAs when no site-specific data are available (see eg Long et al 1995) Given the availability of substantial site-specific data the generic SQVs should not be used at all or at a minimum given very low weight and the references to them should be removed from the conclusions

The ERA also gives moderate weight to the results of the Toxicity Identification Evaluation (TIE) (Table D4-5) The ERA concludes from this Phase I TIE that PCBs may be the main causal agent in the toxicity studies (p D-78) However the TIE was not a definitive study and was not designed to provide an independent evaluation of effects and the results of the TIE are inconclusive showing only that non-polar organic chemicals were likely responsible for the observed toxicity As a result while the results of the TIE provide some evidence as to the degree to which observed effects can be linked to PCBs rather than other COPCs the TIE study should be removed as a separate line of evidence

314 Need to Acknowledge Additional Uncertainties There are a number of uncertainties associated with the benthic invertebrate studies Some of these are acknowledged in the text (pp D-95 through D-98) but other critical uncertainties are not The text should be revised to acknowledge the following uncertainties

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Lack of concordance between benthic community and sediment toxicity study results At the four stations for which there are both sediment toxicity test data and benthic community data those results are contradictory The sediment toxicity tests show a toxic response for most endpoints (especially at Stations 7 and 8) whereas the benthic community analyses do not (see Figure D4-15) GE recommends that the ERA be revised to discuss this point in the uncertainty section and also to carry this through to the conclusions in terms of the ability to extrapolate the potential for adverse effects to downstream locations

Inconsistent patterns oftPCB concentrations in sediment and tissues The ERA likewise does not discuss the fact that the median tPCB concentrations in sediments and those in tissue are not consistent (eg elevated tPCB concentrations in sediments were not co-located with those in tissue) (compare Figure 33-3 on p 3-18 with Figure 33-6 on p 3-22) These inconsistencies raise questions regarding the reliability of using median sediment concentrations as a measure of exposure for benthic invertebrates They also limit the usefulness of the biota sediment accumulation factors (BSAFs) which range from 08 to 61 (p D-32) in predicting tissue levels from sediment concentrations These inconsistencies should be acknowledged in the discussion of tissue chemistry (Section 335 pp 3-21 and 3-23) and the implications relative to estimating exposure should be addressed in the uncertainty section

Calculation of LC$o and ICso values The toxicity test endpoints presented in Tables D4-1 through D4-3 based on statistical analyses have a number of significant uncertainties Specifically uncertainties are associated with the results in which (a) the chi-square value exceeds the critical value in the derivation of LCjos and LC2os (20 out of 54 endpoints) (b) visual observations rather than the probit analyses were used because the model did not converge (2 out of 54 endpoints) and (c) there was an interrupted dose-response (9 of 54 endpoints) These difficulties with the statistical analyses are indicative of inconsistencies in the dose-response relationships that result in uncertainty surrounding the threshold values These uncertainties should be addressed (Tables D4-1 - D4-3) In addition no explanation is provided for why the highest dose (772 mgkg) for H azteca 48-h survival is excluded from the effects threshold analysis (Table D4-1) Additional information should be included regarding its exclusion or the analyses should be redone using the results of this treatment

Use of single samples to characterize sediment in used in bioassays A discussion of the uncertainty associated with determining exposure values of sediment composites used in toxicity testing based on a single chemistry sample should be provided (p D-17) Alternatively if multiple samples were used to evaluate potential heterogeneity in these composites to confirm that sediment was completely mixed then those data should be provided

315 Need for Additional Clarification and Information This section describes a number of issues for which the next draft of the ERA should provide clarification or additional data or analyses

Tissue effects thresholds from the literature The ERA states that the literature review was focused on Aroclor 1260 and 1254 (p 3-14) It should be revised to state that no effects thresholds were found based on studies with Aroclor 1260 and that only studies of tPCBs Aroclor 1254 and Clophen A50 were used to derive these thresholds The figures summarizing the literature effects thresholds should also be revised to indicate which study is associated with the effects reported (eg in Figure 44-13)

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and to indicate that studies with Clophen A50 are included in the summary In addition congenershyspecific studies should be removed from the literature review (Table D3-5 and Attachment DI) as they are not appropriate surrogates for tPCB toxicity

Multi-dimensional scaling analysis The results of the multi-dimensional scaling (MDS) statistical analyses used to develop Figures D3-15 through D3-17 should be presented This will provide important information regarding the relative contribution of different factors in this multivariate analysis

Derivation of MATCs The ERA does not explain explicitly how the sediment MATC of 3 mgkg tPCB (p 3-72) used to assess the extent of risks downstream from the PSA was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should specifically document the derivation of the MATC value used

32 Amphibians In the assessment of amphibians the ERA derives toxicity thresholds (MATCs) of 1 mgkg in both tissue (based on the literature) and sediments (based on the results of EPAs wood frog study) As discussed below GE believes that neither of these thresholds is supported by the underlying studies and that they should be higher Moreover in evaluating the results of the wood frog study the ERA does not consider certain endpoints (metamorphosis and mortality) that have clear ecological relevance these endpoints should be included in the evaluation In addition as further discussed in these comments we urge EPA to (a) give lower weight to the results of the leopard frog study and explicitly recognize its use of external reference frogs (b) recognize additional specified uncertainties in the amphibian assessment (c) clarify or present additional data or analyses on certain issues (d) modify the extrapolation to reaches downstream of Woods Pond and (e) correct an error in the text1

321 Lack of Literature Support for a Toxicity Threshold of 1 mgkg tPCBs in Tissue The ERA specifies a toxicity threshold of 1 mgkg in tissue based on a review of the literature (pp 4shy75 E-96) The studies and results used in this review are summarized in Figures 44-13 and E3-37 However the two tPCB LOAELs (called LOELs in these figures) below 1 mgkg shown in these figures are not supported by the underlying study (Gutleb et al 2000) One of these effects levels for time to metamorphosis for the African clawed frog is based on exposure to PCB 126 although tissue chemistry was analyzed as tPCBs Comparing tPCB concentrations to effects levels from a study in which larvae were exposed to PCB 126 would substantially overstate tPCB toxicity and hence this effect level should not be used to evaluate potential tPCB effects The second LOAEL for the European common frog is 024 mgkg tPCBs (wet weight2) in tissue (based on exposure to Clophen A50) However at that concentration there was no adverse effect body weight in the exposed frogs was higher not lower than in the control frogs In fact there was no significant effect on body weight at the highest tissue concentration used in this study (112 mgkg tPCBs wet weight) Hence the latter

1 As noted in Section 1 EPA has also agreed to include the frog study sponsored by GE (Resetarits 2002) in the next draft of the ERA In addition GE has recently completed a study of leopard frog egg masses in the PSA and is providing a report on that study to EPA (ARCADIS 2003) That study should likewise be included in the next draft of the ERA

2 As converted from lipid weight in Attachment E2

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value should be reported as an unbounded NOAEL for that endpoint and the value reported as a LOAEL (024 mgkg) should be removed from these figures

Additional concerns associated with the summary of the literature effects are related to the interpretation of the frequency of occurrence of adverse effects (p 4-56 and E-81) First three LOAELs are cited for mortality based on a single experiment (Savage et al 2002) (Figure 4431 p 4shy57 and E3-37 p 60) By definition a LOAEL is the lowest concentration in an experiment for which there is a statistically significant difference relative to the control therefore only the LOAEL at approximately 6 mgkg from this study should be included in this figure When the erroneous LOAEL (Gutleb et al 2000) and the redundant LOAELs (Savage et al 2002) are removed the frequency of adverse effect analysis indicates that 4 out of 12 endpoints (for tPCBs) or 33 demonstrate adverse effects at concentrations greater than 1 mgkg and that in fact no adverse effects are observed below 6 mgkg

In addition the meaning of this frequency of adverse effects is not clear because there are substantive differences between the nature of effects observed For example the endpoints of reduced activity or swimming speed may or may not have the same severity of impact to an individual as increased mortality This distinction is lost in a simple evaluation of frequency of effects between different endpoints in various literature studies

Based on the above discussion the statement that [tjhere were six instances of adverse effects occurring between 1 and 10 mgkg (pp 4-56 and E-81) should be revised For tPCBs there are only three LOAELs (ie incidence of adverse effects) between 1 and 10 mgkg and all them are at or above 6 mgkg The text should be revised accordingly If the interpretation of these studies based on the frequency of adverse effects is retained that text should also be revised and uncertainties associated with direct comparisons of the different kinds of effects included in this analysis should be acknowledged

322 Lack of Support for a Sediment Toxicity Threshold of 1 mgkg Based on Wood Frog Study

The sediment toxicity threshold of 1 mgkg is apparently based primarily on an analysis of the results of EPAs wood frog study However the description of the results of that study states that [e]cologically significant adverse effects in late stage juvenile wood frogs occurred in the sediment tPCB concentration range of 10 to 60 mgkg although responses of lesser magnitude yet statistically significant were observed at 5 mgkg tPCB and lower (p 4-60) The latter statement (which may be the basis for the threshold) is apparently derived from the wood frog NOAELs and LOAELs presented in Table E4-2 However there are several problems or inconsistencies in the derivation of site-specific NOAELs and LOAELs presented in Table E4-2

bull In several instances the NOAELs and LOAELs do not coincide with sediment concentrations that are associated with the effects data For example the spatially weighted mean tPCB value of 136 mgkg is presented as either a NOAEL or LOAEL for all four endpoints in Table E4-2 However it appears that this value is associated with a vernal pool (46-VP-4 Table E2-8) that has no effects data associated with it (see Tables E3-5- E3-6 and E 310 - E3-11)

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bull It appears that the reference WML-1 has been excluded from the calculation of NOAELs and LOAELs for Phase III metamorphs because of zero response at this concentration(Table E4-2) This exclusion is not warranted While the text refers to the tissue tPCB concentration for reference location WML-1 in the Phase III of the wood frog study as anomalous (eg p 4-52) no problems with data quality are reported that would indicate that the organism did not in fact have a tissue burden of 44 mgkg tPCBs As a result responses associated with this exposure level should be considered to represent part of the range of effects and all analyses of exposure and effect should include this reference site Statistical comparisons with a zero value are commonly made using a value marginally greater than zero (eg 000001)

bull Concentration-response relationships for each endpoint were evaluated using both (1) the most synoptic chemistry value paired with each toxicity endpoint (also referred to as vernal pool sediment) and (2) a combined data set used to generate a spatially weighted surface average (pp 4shy16 mdash 4-17) Given the variability in sediment concentrations the samples used in the laboratory toxicity study should not be assumed to be equivalent to the surface weighted average The synoptic (ie vernal pool) data reflect the actual tPCB concentrations measured in sediments used in the laboratory exposures and should thus should be used for analyses of the Phase I wood frog study which was conducted in the laboratory The surface weighted averages should be used for the analysis of Phase II and Phase III studies in which larvae and metamorphs were exposed in the field as they encompass the range of concentrations to which the growing larvae and metamorphs might have been exposed to The NOAELs LOAELs and point estimates for effects concentrations (eg LC50 and LC20) (Table E4-2) should be revised accordingly

bull Table E4-2 states that the reference site had no malformed specimens (Phase II metamorphs percent malformed) In fact Table E3-11 indicates that reference site WML-3 had 29 malformations

Moreover the toxicity threshold for wood frogs was derived based only on endpoints that showed effects The ERA states that if no discern[i]ble differences in effect levels across treatments were observed (ie inadequate range in response variable) the effects endpoint was not considered in the detailed statistical evaluation (p E-90) As a result as discussed in the next section the lack of PCB-related effects for key endpoints (ie mortality and metamorphosis) were not considered in the derivation of the effects threshold Consideration of the results for those omitted endpoints shows further that the sediment MATC of 1 mgkg is too low

We also note that although Appendix E presents tissue-based HQs for leopard frogs and wood frogs (pp E-96 - E-98) Section 12 of the ERA presents only sediment-based HQs (Figures 122-1 and p 12shy7) Tissue concentrations provide a more direct measure of exposure than do sediment concentrations and hence the tissue-based rather than sediment-based HQs should be used in Section 12

323 Need to Consider Additional Relevant Endpoints in Wood Frog Study As noted above in evaluating the results of the wood frog study two endpoints with clear ecological relevance ~ metamorphosis and mortality -- were screened out of the formal concentration-response modeling due to a lack of discern[i]ble differences in effect levels across treatments (p E-90) However these two endpoints integrate other effects (ie the most serious effect of malformations would be reduced metamorphosis and increased mortality) and should be carried through the

concentration-response evaluation If no concentration-response curve can be derived because there were no effects then the highest dose should be treated as a NOAEL for these endpoints the LC50

should be expressed as gt highest dose and both mortality and metamorphosis should be considered subsequently as part of the lines-of-evidence evaluation

324 Evaluation of the Leopard Frog Study EPAs leopard frog study receives the same overall weight (moderatehigh) as its wood frog study in the weight-of evidence-evaluation (Table 45-4 p 4-69) Considering the significant problems with the leopard frog study as detailed in GEs comments on this study (BBL Sciences et al 2003a) it should be accorded a low weight

Moreover the text does not consistently acknowledge that reference frogs for the leopard frog study were obtained from a biological supply company For readers unfamiliar with the underlying study this could lead to misinterpretations of the results presented The text should be modified to clearly represent this aspect of the leopard frog study as well as additional qualifications as follows

bull The first time the study design of the leopard frog study is presented it should be clearly stated that no frogs or eggslarvae were found in the reference areas (p 4-13)

bull The text that describes comparisons between both the toxicity studies and the community evaluations and appropriately matched field references (p 4-27) should be revised to indicate that for the leopard frog study the field reference was limited to sediment not frogs collected from a reference pond

bull Although the text states that reference ponds were surveyed for eggs and larvae it does not indicate that in addition to no eggs or larvae being found at four of nine contaminated sites none were found at the reference sites (p 4-35)

bull Similarly the summary of female leopard frog reproductive fitness identifies all of the Housatonic River sites that were not gravid (did not have eggs mature enough for successful fertilization) (p 4shy30) It should also indicate that R2 (external reference) did not have any successful fertilization

325 Need to Acknowledge Additional Uncertainties While the ERA acknowledges some uncertainties associated with the amphibian studies (pp 4-70 4shy73 E-108-110) other critical uncertainties are not acknowledged For example there are uncertainties associated with the concentration-response analysis (eg ECsos ECaos) based on the poor fit of the data in the probit analysis Contrary to the statement that most endpoints followed a fairly smooth concentration-response (text box p 4-60) Table E4-2 indicates that only one of 11 of the ECsos presented (ie Phase III metamorph percent malformed based on comparisons with the lowest vernal pool sediment tPCB concentration) appears to be appropriately described by the probit analysis The other ECsos were described as (a) outside data range confidence limits increase (111) (b) probit model had poor fit to data confidence limits increase (111) (c) calculated with linear interpolation no confidence limits can be calculated (311) and (d) based on visual inspection of data (511) These uncertainties should be recognized

326 Need for Additional Information There are a number of issues on which we urge EPA to provide additional information in the next draft of the ERA

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Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

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Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

Lack of concordance between benthic community and sediment toxicity study results At the four stations for which there are both sediment toxicity test data and benthic community data those results are contradictory The sediment toxicity tests show a toxic response for most endpoints (especially at Stations 7 and 8) whereas the benthic community analyses do not (see Figure D4-15) GE recommends that the ERA be revised to discuss this point in the uncertainty section and also to carry this through to the conclusions in terms of the ability to extrapolate the potential for adverse effects to downstream locations

Inconsistent patterns oftPCB concentrations in sediment and tissues The ERA likewise does not discuss the fact that the median tPCB concentrations in sediments and those in tissue are not consistent (eg elevated tPCB concentrations in sediments were not co-located with those in tissue) (compare Figure 33-3 on p 3-18 with Figure 33-6 on p 3-22) These inconsistencies raise questions regarding the reliability of using median sediment concentrations as a measure of exposure for benthic invertebrates They also limit the usefulness of the biota sediment accumulation factors (BSAFs) which range from 08 to 61 (p D-32) in predicting tissue levels from sediment concentrations These inconsistencies should be acknowledged in the discussion of tissue chemistry (Section 335 pp 3-21 and 3-23) and the implications relative to estimating exposure should be addressed in the uncertainty section

Calculation of LC$o and ICso values The toxicity test endpoints presented in Tables D4-1 through D4-3 based on statistical analyses have a number of significant uncertainties Specifically uncertainties are associated with the results in which (a) the chi-square value exceeds the critical value in the derivation of LCjos and LC2os (20 out of 54 endpoints) (b) visual observations rather than the probit analyses were used because the model did not converge (2 out of 54 endpoints) and (c) there was an interrupted dose-response (9 of 54 endpoints) These difficulties with the statistical analyses are indicative of inconsistencies in the dose-response relationships that result in uncertainty surrounding the threshold values These uncertainties should be addressed (Tables D4-1 - D4-3) In addition no explanation is provided for why the highest dose (772 mgkg) for H azteca 48-h survival is excluded from the effects threshold analysis (Table D4-1) Additional information should be included regarding its exclusion or the analyses should be redone using the results of this treatment

Use of single samples to characterize sediment in used in bioassays A discussion of the uncertainty associated with determining exposure values of sediment composites used in toxicity testing based on a single chemistry sample should be provided (p D-17) Alternatively if multiple samples were used to evaluate potential heterogeneity in these composites to confirm that sediment was completely mixed then those data should be provided

315 Need for Additional Clarification and Information This section describes a number of issues for which the next draft of the ERA should provide clarification or additional data or analyses

Tissue effects thresholds from the literature The ERA states that the literature review was focused on Aroclor 1260 and 1254 (p 3-14) It should be revised to state that no effects thresholds were found based on studies with Aroclor 1260 and that only studies of tPCBs Aroclor 1254 and Clophen A50 were used to derive these thresholds The figures summarizing the literature effects thresholds should also be revised to indicate which study is associated with the effects reported (eg in Figure 44-13)

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and to indicate that studies with Clophen A50 are included in the summary In addition congenershyspecific studies should be removed from the literature review (Table D3-5 and Attachment DI) as they are not appropriate surrogates for tPCB toxicity

Multi-dimensional scaling analysis The results of the multi-dimensional scaling (MDS) statistical analyses used to develop Figures D3-15 through D3-17 should be presented This will provide important information regarding the relative contribution of different factors in this multivariate analysis

Derivation of MATCs The ERA does not explain explicitly how the sediment MATC of 3 mgkg tPCB (p 3-72) used to assess the extent of risks downstream from the PSA was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should specifically document the derivation of the MATC value used

32 Amphibians In the assessment of amphibians the ERA derives toxicity thresholds (MATCs) of 1 mgkg in both tissue (based on the literature) and sediments (based on the results of EPAs wood frog study) As discussed below GE believes that neither of these thresholds is supported by the underlying studies and that they should be higher Moreover in evaluating the results of the wood frog study the ERA does not consider certain endpoints (metamorphosis and mortality) that have clear ecological relevance these endpoints should be included in the evaluation In addition as further discussed in these comments we urge EPA to (a) give lower weight to the results of the leopard frog study and explicitly recognize its use of external reference frogs (b) recognize additional specified uncertainties in the amphibian assessment (c) clarify or present additional data or analyses on certain issues (d) modify the extrapolation to reaches downstream of Woods Pond and (e) correct an error in the text1

321 Lack of Literature Support for a Toxicity Threshold of 1 mgkg tPCBs in Tissue The ERA specifies a toxicity threshold of 1 mgkg in tissue based on a review of the literature (pp 4shy75 E-96) The studies and results used in this review are summarized in Figures 44-13 and E3-37 However the two tPCB LOAELs (called LOELs in these figures) below 1 mgkg shown in these figures are not supported by the underlying study (Gutleb et al 2000) One of these effects levels for time to metamorphosis for the African clawed frog is based on exposure to PCB 126 although tissue chemistry was analyzed as tPCBs Comparing tPCB concentrations to effects levels from a study in which larvae were exposed to PCB 126 would substantially overstate tPCB toxicity and hence this effect level should not be used to evaluate potential tPCB effects The second LOAEL for the European common frog is 024 mgkg tPCBs (wet weight2) in tissue (based on exposure to Clophen A50) However at that concentration there was no adverse effect body weight in the exposed frogs was higher not lower than in the control frogs In fact there was no significant effect on body weight at the highest tissue concentration used in this study (112 mgkg tPCBs wet weight) Hence the latter

1 As noted in Section 1 EPA has also agreed to include the frog study sponsored by GE (Resetarits 2002) in the next draft of the ERA In addition GE has recently completed a study of leopard frog egg masses in the PSA and is providing a report on that study to EPA (ARCADIS 2003) That study should likewise be included in the next draft of the ERA

2 As converted from lipid weight in Attachment E2

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value should be reported as an unbounded NOAEL for that endpoint and the value reported as a LOAEL (024 mgkg) should be removed from these figures

Additional concerns associated with the summary of the literature effects are related to the interpretation of the frequency of occurrence of adverse effects (p 4-56 and E-81) First three LOAELs are cited for mortality based on a single experiment (Savage et al 2002) (Figure 4431 p 4shy57 and E3-37 p 60) By definition a LOAEL is the lowest concentration in an experiment for which there is a statistically significant difference relative to the control therefore only the LOAEL at approximately 6 mgkg from this study should be included in this figure When the erroneous LOAEL (Gutleb et al 2000) and the redundant LOAELs (Savage et al 2002) are removed the frequency of adverse effect analysis indicates that 4 out of 12 endpoints (for tPCBs) or 33 demonstrate adverse effects at concentrations greater than 1 mgkg and that in fact no adverse effects are observed below 6 mgkg

In addition the meaning of this frequency of adverse effects is not clear because there are substantive differences between the nature of effects observed For example the endpoints of reduced activity or swimming speed may or may not have the same severity of impact to an individual as increased mortality This distinction is lost in a simple evaluation of frequency of effects between different endpoints in various literature studies

Based on the above discussion the statement that [tjhere were six instances of adverse effects occurring between 1 and 10 mgkg (pp 4-56 and E-81) should be revised For tPCBs there are only three LOAELs (ie incidence of adverse effects) between 1 and 10 mgkg and all them are at or above 6 mgkg The text should be revised accordingly If the interpretation of these studies based on the frequency of adverse effects is retained that text should also be revised and uncertainties associated with direct comparisons of the different kinds of effects included in this analysis should be acknowledged

322 Lack of Support for a Sediment Toxicity Threshold of 1 mgkg Based on Wood Frog Study

The sediment toxicity threshold of 1 mgkg is apparently based primarily on an analysis of the results of EPAs wood frog study However the description of the results of that study states that [e]cologically significant adverse effects in late stage juvenile wood frogs occurred in the sediment tPCB concentration range of 10 to 60 mgkg although responses of lesser magnitude yet statistically significant were observed at 5 mgkg tPCB and lower (p 4-60) The latter statement (which may be the basis for the threshold) is apparently derived from the wood frog NOAELs and LOAELs presented in Table E4-2 However there are several problems or inconsistencies in the derivation of site-specific NOAELs and LOAELs presented in Table E4-2

bull In several instances the NOAELs and LOAELs do not coincide with sediment concentrations that are associated with the effects data For example the spatially weighted mean tPCB value of 136 mgkg is presented as either a NOAEL or LOAEL for all four endpoints in Table E4-2 However it appears that this value is associated with a vernal pool (46-VP-4 Table E2-8) that has no effects data associated with it (see Tables E3-5- E3-6 and E 310 - E3-11)

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bull It appears that the reference WML-1 has been excluded from the calculation of NOAELs and LOAELs for Phase III metamorphs because of zero response at this concentration(Table E4-2) This exclusion is not warranted While the text refers to the tissue tPCB concentration for reference location WML-1 in the Phase III of the wood frog study as anomalous (eg p 4-52) no problems with data quality are reported that would indicate that the organism did not in fact have a tissue burden of 44 mgkg tPCBs As a result responses associated with this exposure level should be considered to represent part of the range of effects and all analyses of exposure and effect should include this reference site Statistical comparisons with a zero value are commonly made using a value marginally greater than zero (eg 000001)

bull Concentration-response relationships for each endpoint were evaluated using both (1) the most synoptic chemistry value paired with each toxicity endpoint (also referred to as vernal pool sediment) and (2) a combined data set used to generate a spatially weighted surface average (pp 4shy16 mdash 4-17) Given the variability in sediment concentrations the samples used in the laboratory toxicity study should not be assumed to be equivalent to the surface weighted average The synoptic (ie vernal pool) data reflect the actual tPCB concentrations measured in sediments used in the laboratory exposures and should thus should be used for analyses of the Phase I wood frog study which was conducted in the laboratory The surface weighted averages should be used for the analysis of Phase II and Phase III studies in which larvae and metamorphs were exposed in the field as they encompass the range of concentrations to which the growing larvae and metamorphs might have been exposed to The NOAELs LOAELs and point estimates for effects concentrations (eg LC50 and LC20) (Table E4-2) should be revised accordingly

bull Table E4-2 states that the reference site had no malformed specimens (Phase II metamorphs percent malformed) In fact Table E3-11 indicates that reference site WML-3 had 29 malformations

Moreover the toxicity threshold for wood frogs was derived based only on endpoints that showed effects The ERA states that if no discern[i]ble differences in effect levels across treatments were observed (ie inadequate range in response variable) the effects endpoint was not considered in the detailed statistical evaluation (p E-90) As a result as discussed in the next section the lack of PCB-related effects for key endpoints (ie mortality and metamorphosis) were not considered in the derivation of the effects threshold Consideration of the results for those omitted endpoints shows further that the sediment MATC of 1 mgkg is too low

We also note that although Appendix E presents tissue-based HQs for leopard frogs and wood frogs (pp E-96 - E-98) Section 12 of the ERA presents only sediment-based HQs (Figures 122-1 and p 12shy7) Tissue concentrations provide a more direct measure of exposure than do sediment concentrations and hence the tissue-based rather than sediment-based HQs should be used in Section 12

323 Need to Consider Additional Relevant Endpoints in Wood Frog Study As noted above in evaluating the results of the wood frog study two endpoints with clear ecological relevance ~ metamorphosis and mortality -- were screened out of the formal concentration-response modeling due to a lack of discern[i]ble differences in effect levels across treatments (p E-90) However these two endpoints integrate other effects (ie the most serious effect of malformations would be reduced metamorphosis and increased mortality) and should be carried through the

concentration-response evaluation If no concentration-response curve can be derived because there were no effects then the highest dose should be treated as a NOAEL for these endpoints the LC50

should be expressed as gt highest dose and both mortality and metamorphosis should be considered subsequently as part of the lines-of-evidence evaluation

324 Evaluation of the Leopard Frog Study EPAs leopard frog study receives the same overall weight (moderatehigh) as its wood frog study in the weight-of evidence-evaluation (Table 45-4 p 4-69) Considering the significant problems with the leopard frog study as detailed in GEs comments on this study (BBL Sciences et al 2003a) it should be accorded a low weight

Moreover the text does not consistently acknowledge that reference frogs for the leopard frog study were obtained from a biological supply company For readers unfamiliar with the underlying study this could lead to misinterpretations of the results presented The text should be modified to clearly represent this aspect of the leopard frog study as well as additional qualifications as follows

bull The first time the study design of the leopard frog study is presented it should be clearly stated that no frogs or eggslarvae were found in the reference areas (p 4-13)

bull The text that describes comparisons between both the toxicity studies and the community evaluations and appropriately matched field references (p 4-27) should be revised to indicate that for the leopard frog study the field reference was limited to sediment not frogs collected from a reference pond

bull Although the text states that reference ponds were surveyed for eggs and larvae it does not indicate that in addition to no eggs or larvae being found at four of nine contaminated sites none were found at the reference sites (p 4-35)

bull Similarly the summary of female leopard frog reproductive fitness identifies all of the Housatonic River sites that were not gravid (did not have eggs mature enough for successful fertilization) (p 4shy30) It should also indicate that R2 (external reference) did not have any successful fertilization

325 Need to Acknowledge Additional Uncertainties While the ERA acknowledges some uncertainties associated with the amphibian studies (pp 4-70 4shy73 E-108-110) other critical uncertainties are not acknowledged For example there are uncertainties associated with the concentration-response analysis (eg ECsos ECaos) based on the poor fit of the data in the probit analysis Contrary to the statement that most endpoints followed a fairly smooth concentration-response (text box p 4-60) Table E4-2 indicates that only one of 11 of the ECsos presented (ie Phase III metamorph percent malformed based on comparisons with the lowest vernal pool sediment tPCB concentration) appears to be appropriately described by the probit analysis The other ECsos were described as (a) outside data range confidence limits increase (111) (b) probit model had poor fit to data confidence limits increase (111) (c) calculated with linear interpolation no confidence limits can be calculated (311) and (d) based on visual inspection of data (511) These uncertainties should be recognized

326 Need for Additional Information There are a number of issues on which we urge EPA to provide additional information in the next draft of the ERA

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Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

__

Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

and to indicate that studies with Clophen A50 are included in the summary In addition congenershyspecific studies should be removed from the literature review (Table D3-5 and Attachment DI) as they are not appropriate surrogates for tPCB toxicity

Multi-dimensional scaling analysis The results of the multi-dimensional scaling (MDS) statistical analyses used to develop Figures D3-15 through D3-17 should be presented This will provide important information regarding the relative contribution of different factors in this multivariate analysis

Derivation of MATCs The ERA does not explain explicitly how the sediment MATC of 3 mgkg tPCB (p 3-72) used to assess the extent of risks downstream from the PSA was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should specifically document the derivation of the MATC value used

32 Amphibians In the assessment of amphibians the ERA derives toxicity thresholds (MATCs) of 1 mgkg in both tissue (based on the literature) and sediments (based on the results of EPAs wood frog study) As discussed below GE believes that neither of these thresholds is supported by the underlying studies and that they should be higher Moreover in evaluating the results of the wood frog study the ERA does not consider certain endpoints (metamorphosis and mortality) that have clear ecological relevance these endpoints should be included in the evaluation In addition as further discussed in these comments we urge EPA to (a) give lower weight to the results of the leopard frog study and explicitly recognize its use of external reference frogs (b) recognize additional specified uncertainties in the amphibian assessment (c) clarify or present additional data or analyses on certain issues (d) modify the extrapolation to reaches downstream of Woods Pond and (e) correct an error in the text1

321 Lack of Literature Support for a Toxicity Threshold of 1 mgkg tPCBs in Tissue The ERA specifies a toxicity threshold of 1 mgkg in tissue based on a review of the literature (pp 4shy75 E-96) The studies and results used in this review are summarized in Figures 44-13 and E3-37 However the two tPCB LOAELs (called LOELs in these figures) below 1 mgkg shown in these figures are not supported by the underlying study (Gutleb et al 2000) One of these effects levels for time to metamorphosis for the African clawed frog is based on exposure to PCB 126 although tissue chemistry was analyzed as tPCBs Comparing tPCB concentrations to effects levels from a study in which larvae were exposed to PCB 126 would substantially overstate tPCB toxicity and hence this effect level should not be used to evaluate potential tPCB effects The second LOAEL for the European common frog is 024 mgkg tPCBs (wet weight2) in tissue (based on exposure to Clophen A50) However at that concentration there was no adverse effect body weight in the exposed frogs was higher not lower than in the control frogs In fact there was no significant effect on body weight at the highest tissue concentration used in this study (112 mgkg tPCBs wet weight) Hence the latter

1 As noted in Section 1 EPA has also agreed to include the frog study sponsored by GE (Resetarits 2002) in the next draft of the ERA In addition GE has recently completed a study of leopard frog egg masses in the PSA and is providing a report on that study to EPA (ARCADIS 2003) That study should likewise be included in the next draft of the ERA

2 As converted from lipid weight in Attachment E2

_

value should be reported as an unbounded NOAEL for that endpoint and the value reported as a LOAEL (024 mgkg) should be removed from these figures

Additional concerns associated with the summary of the literature effects are related to the interpretation of the frequency of occurrence of adverse effects (p 4-56 and E-81) First three LOAELs are cited for mortality based on a single experiment (Savage et al 2002) (Figure 4431 p 4shy57 and E3-37 p 60) By definition a LOAEL is the lowest concentration in an experiment for which there is a statistically significant difference relative to the control therefore only the LOAEL at approximately 6 mgkg from this study should be included in this figure When the erroneous LOAEL (Gutleb et al 2000) and the redundant LOAELs (Savage et al 2002) are removed the frequency of adverse effect analysis indicates that 4 out of 12 endpoints (for tPCBs) or 33 demonstrate adverse effects at concentrations greater than 1 mgkg and that in fact no adverse effects are observed below 6 mgkg

In addition the meaning of this frequency of adverse effects is not clear because there are substantive differences between the nature of effects observed For example the endpoints of reduced activity or swimming speed may or may not have the same severity of impact to an individual as increased mortality This distinction is lost in a simple evaluation of frequency of effects between different endpoints in various literature studies

Based on the above discussion the statement that [tjhere were six instances of adverse effects occurring between 1 and 10 mgkg (pp 4-56 and E-81) should be revised For tPCBs there are only three LOAELs (ie incidence of adverse effects) between 1 and 10 mgkg and all them are at or above 6 mgkg The text should be revised accordingly If the interpretation of these studies based on the frequency of adverse effects is retained that text should also be revised and uncertainties associated with direct comparisons of the different kinds of effects included in this analysis should be acknowledged

322 Lack of Support for a Sediment Toxicity Threshold of 1 mgkg Based on Wood Frog Study

The sediment toxicity threshold of 1 mgkg is apparently based primarily on an analysis of the results of EPAs wood frog study However the description of the results of that study states that [e]cologically significant adverse effects in late stage juvenile wood frogs occurred in the sediment tPCB concentration range of 10 to 60 mgkg although responses of lesser magnitude yet statistically significant were observed at 5 mgkg tPCB and lower (p 4-60) The latter statement (which may be the basis for the threshold) is apparently derived from the wood frog NOAELs and LOAELs presented in Table E4-2 However there are several problems or inconsistencies in the derivation of site-specific NOAELs and LOAELs presented in Table E4-2

bull In several instances the NOAELs and LOAELs do not coincide with sediment concentrations that are associated with the effects data For example the spatially weighted mean tPCB value of 136 mgkg is presented as either a NOAEL or LOAEL for all four endpoints in Table E4-2 However it appears that this value is associated with a vernal pool (46-VP-4 Table E2-8) that has no effects data associated with it (see Tables E3-5- E3-6 and E 310 - E3-11)

3-5

__

bull It appears that the reference WML-1 has been excluded from the calculation of NOAELs and LOAELs for Phase III metamorphs because of zero response at this concentration(Table E4-2) This exclusion is not warranted While the text refers to the tissue tPCB concentration for reference location WML-1 in the Phase III of the wood frog study as anomalous (eg p 4-52) no problems with data quality are reported that would indicate that the organism did not in fact have a tissue burden of 44 mgkg tPCBs As a result responses associated with this exposure level should be considered to represent part of the range of effects and all analyses of exposure and effect should include this reference site Statistical comparisons with a zero value are commonly made using a value marginally greater than zero (eg 000001)

bull Concentration-response relationships for each endpoint were evaluated using both (1) the most synoptic chemistry value paired with each toxicity endpoint (also referred to as vernal pool sediment) and (2) a combined data set used to generate a spatially weighted surface average (pp 4shy16 mdash 4-17) Given the variability in sediment concentrations the samples used in the laboratory toxicity study should not be assumed to be equivalent to the surface weighted average The synoptic (ie vernal pool) data reflect the actual tPCB concentrations measured in sediments used in the laboratory exposures and should thus should be used for analyses of the Phase I wood frog study which was conducted in the laboratory The surface weighted averages should be used for the analysis of Phase II and Phase III studies in which larvae and metamorphs were exposed in the field as they encompass the range of concentrations to which the growing larvae and metamorphs might have been exposed to The NOAELs LOAELs and point estimates for effects concentrations (eg LC50 and LC20) (Table E4-2) should be revised accordingly

bull Table E4-2 states that the reference site had no malformed specimens (Phase II metamorphs percent malformed) In fact Table E3-11 indicates that reference site WML-3 had 29 malformations

Moreover the toxicity threshold for wood frogs was derived based only on endpoints that showed effects The ERA states that if no discern[i]ble differences in effect levels across treatments were observed (ie inadequate range in response variable) the effects endpoint was not considered in the detailed statistical evaluation (p E-90) As a result as discussed in the next section the lack of PCB-related effects for key endpoints (ie mortality and metamorphosis) were not considered in the derivation of the effects threshold Consideration of the results for those omitted endpoints shows further that the sediment MATC of 1 mgkg is too low

We also note that although Appendix E presents tissue-based HQs for leopard frogs and wood frogs (pp E-96 - E-98) Section 12 of the ERA presents only sediment-based HQs (Figures 122-1 and p 12shy7) Tissue concentrations provide a more direct measure of exposure than do sediment concentrations and hence the tissue-based rather than sediment-based HQs should be used in Section 12

323 Need to Consider Additional Relevant Endpoints in Wood Frog Study As noted above in evaluating the results of the wood frog study two endpoints with clear ecological relevance ~ metamorphosis and mortality -- were screened out of the formal concentration-response modeling due to a lack of discern[i]ble differences in effect levels across treatments (p E-90) However these two endpoints integrate other effects (ie the most serious effect of malformations would be reduced metamorphosis and increased mortality) and should be carried through the

concentration-response evaluation If no concentration-response curve can be derived because there were no effects then the highest dose should be treated as a NOAEL for these endpoints the LC50

should be expressed as gt highest dose and both mortality and metamorphosis should be considered subsequently as part of the lines-of-evidence evaluation

324 Evaluation of the Leopard Frog Study EPAs leopard frog study receives the same overall weight (moderatehigh) as its wood frog study in the weight-of evidence-evaluation (Table 45-4 p 4-69) Considering the significant problems with the leopard frog study as detailed in GEs comments on this study (BBL Sciences et al 2003a) it should be accorded a low weight

Moreover the text does not consistently acknowledge that reference frogs for the leopard frog study were obtained from a biological supply company For readers unfamiliar with the underlying study this could lead to misinterpretations of the results presented The text should be modified to clearly represent this aspect of the leopard frog study as well as additional qualifications as follows

bull The first time the study design of the leopard frog study is presented it should be clearly stated that no frogs or eggslarvae were found in the reference areas (p 4-13)

bull The text that describes comparisons between both the toxicity studies and the community evaluations and appropriately matched field references (p 4-27) should be revised to indicate that for the leopard frog study the field reference was limited to sediment not frogs collected from a reference pond

bull Although the text states that reference ponds were surveyed for eggs and larvae it does not indicate that in addition to no eggs or larvae being found at four of nine contaminated sites none were found at the reference sites (p 4-35)

bull Similarly the summary of female leopard frog reproductive fitness identifies all of the Housatonic River sites that were not gravid (did not have eggs mature enough for successful fertilization) (p 4shy30) It should also indicate that R2 (external reference) did not have any successful fertilization

325 Need to Acknowledge Additional Uncertainties While the ERA acknowledges some uncertainties associated with the amphibian studies (pp 4-70 4shy73 E-108-110) other critical uncertainties are not acknowledged For example there are uncertainties associated with the concentration-response analysis (eg ECsos ECaos) based on the poor fit of the data in the probit analysis Contrary to the statement that most endpoints followed a fairly smooth concentration-response (text box p 4-60) Table E4-2 indicates that only one of 11 of the ECsos presented (ie Phase III metamorph percent malformed based on comparisons with the lowest vernal pool sediment tPCB concentration) appears to be appropriately described by the probit analysis The other ECsos were described as (a) outside data range confidence limits increase (111) (b) probit model had poor fit to data confidence limits increase (111) (c) calculated with linear interpolation no confidence limits can be calculated (311) and (d) based on visual inspection of data (511) These uncertainties should be recognized

326 Need for Additional Information There are a number of issues on which we urge EPA to provide additional information in the next draft of the ERA

3-7

__

Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

__

Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

value should be reported as an unbounded NOAEL for that endpoint and the value reported as a LOAEL (024 mgkg) should be removed from these figures

Additional concerns associated with the summary of the literature effects are related to the interpretation of the frequency of occurrence of adverse effects (p 4-56 and E-81) First three LOAELs are cited for mortality based on a single experiment (Savage et al 2002) (Figure 4431 p 4shy57 and E3-37 p 60) By definition a LOAEL is the lowest concentration in an experiment for which there is a statistically significant difference relative to the control therefore only the LOAEL at approximately 6 mgkg from this study should be included in this figure When the erroneous LOAEL (Gutleb et al 2000) and the redundant LOAELs (Savage et al 2002) are removed the frequency of adverse effect analysis indicates that 4 out of 12 endpoints (for tPCBs) or 33 demonstrate adverse effects at concentrations greater than 1 mgkg and that in fact no adverse effects are observed below 6 mgkg

In addition the meaning of this frequency of adverse effects is not clear because there are substantive differences between the nature of effects observed For example the endpoints of reduced activity or swimming speed may or may not have the same severity of impact to an individual as increased mortality This distinction is lost in a simple evaluation of frequency of effects between different endpoints in various literature studies

Based on the above discussion the statement that [tjhere were six instances of adverse effects occurring between 1 and 10 mgkg (pp 4-56 and E-81) should be revised For tPCBs there are only three LOAELs (ie incidence of adverse effects) between 1 and 10 mgkg and all them are at or above 6 mgkg The text should be revised accordingly If the interpretation of these studies based on the frequency of adverse effects is retained that text should also be revised and uncertainties associated with direct comparisons of the different kinds of effects included in this analysis should be acknowledged

322 Lack of Support for a Sediment Toxicity Threshold of 1 mgkg Based on Wood Frog Study

The sediment toxicity threshold of 1 mgkg is apparently based primarily on an analysis of the results of EPAs wood frog study However the description of the results of that study states that [e]cologically significant adverse effects in late stage juvenile wood frogs occurred in the sediment tPCB concentration range of 10 to 60 mgkg although responses of lesser magnitude yet statistically significant were observed at 5 mgkg tPCB and lower (p 4-60) The latter statement (which may be the basis for the threshold) is apparently derived from the wood frog NOAELs and LOAELs presented in Table E4-2 However there are several problems or inconsistencies in the derivation of site-specific NOAELs and LOAELs presented in Table E4-2

bull In several instances the NOAELs and LOAELs do not coincide with sediment concentrations that are associated with the effects data For example the spatially weighted mean tPCB value of 136 mgkg is presented as either a NOAEL or LOAEL for all four endpoints in Table E4-2 However it appears that this value is associated with a vernal pool (46-VP-4 Table E2-8) that has no effects data associated with it (see Tables E3-5- E3-6 and E 310 - E3-11)

3-5

__

bull It appears that the reference WML-1 has been excluded from the calculation of NOAELs and LOAELs for Phase III metamorphs because of zero response at this concentration(Table E4-2) This exclusion is not warranted While the text refers to the tissue tPCB concentration for reference location WML-1 in the Phase III of the wood frog study as anomalous (eg p 4-52) no problems with data quality are reported that would indicate that the organism did not in fact have a tissue burden of 44 mgkg tPCBs As a result responses associated with this exposure level should be considered to represent part of the range of effects and all analyses of exposure and effect should include this reference site Statistical comparisons with a zero value are commonly made using a value marginally greater than zero (eg 000001)

bull Concentration-response relationships for each endpoint were evaluated using both (1) the most synoptic chemistry value paired with each toxicity endpoint (also referred to as vernal pool sediment) and (2) a combined data set used to generate a spatially weighted surface average (pp 4shy16 mdash 4-17) Given the variability in sediment concentrations the samples used in the laboratory toxicity study should not be assumed to be equivalent to the surface weighted average The synoptic (ie vernal pool) data reflect the actual tPCB concentrations measured in sediments used in the laboratory exposures and should thus should be used for analyses of the Phase I wood frog study which was conducted in the laboratory The surface weighted averages should be used for the analysis of Phase II and Phase III studies in which larvae and metamorphs were exposed in the field as they encompass the range of concentrations to which the growing larvae and metamorphs might have been exposed to The NOAELs LOAELs and point estimates for effects concentrations (eg LC50 and LC20) (Table E4-2) should be revised accordingly

bull Table E4-2 states that the reference site had no malformed specimens (Phase II metamorphs percent malformed) In fact Table E3-11 indicates that reference site WML-3 had 29 malformations

Moreover the toxicity threshold for wood frogs was derived based only on endpoints that showed effects The ERA states that if no discern[i]ble differences in effect levels across treatments were observed (ie inadequate range in response variable) the effects endpoint was not considered in the detailed statistical evaluation (p E-90) As a result as discussed in the next section the lack of PCB-related effects for key endpoints (ie mortality and metamorphosis) were not considered in the derivation of the effects threshold Consideration of the results for those omitted endpoints shows further that the sediment MATC of 1 mgkg is too low

We also note that although Appendix E presents tissue-based HQs for leopard frogs and wood frogs (pp E-96 - E-98) Section 12 of the ERA presents only sediment-based HQs (Figures 122-1 and p 12shy7) Tissue concentrations provide a more direct measure of exposure than do sediment concentrations and hence the tissue-based rather than sediment-based HQs should be used in Section 12

323 Need to Consider Additional Relevant Endpoints in Wood Frog Study As noted above in evaluating the results of the wood frog study two endpoints with clear ecological relevance ~ metamorphosis and mortality -- were screened out of the formal concentration-response modeling due to a lack of discern[i]ble differences in effect levels across treatments (p E-90) However these two endpoints integrate other effects (ie the most serious effect of malformations would be reduced metamorphosis and increased mortality) and should be carried through the

concentration-response evaluation If no concentration-response curve can be derived because there were no effects then the highest dose should be treated as a NOAEL for these endpoints the LC50

should be expressed as gt highest dose and both mortality and metamorphosis should be considered subsequently as part of the lines-of-evidence evaluation

324 Evaluation of the Leopard Frog Study EPAs leopard frog study receives the same overall weight (moderatehigh) as its wood frog study in the weight-of evidence-evaluation (Table 45-4 p 4-69) Considering the significant problems with the leopard frog study as detailed in GEs comments on this study (BBL Sciences et al 2003a) it should be accorded a low weight

Moreover the text does not consistently acknowledge that reference frogs for the leopard frog study were obtained from a biological supply company For readers unfamiliar with the underlying study this could lead to misinterpretations of the results presented The text should be modified to clearly represent this aspect of the leopard frog study as well as additional qualifications as follows

bull The first time the study design of the leopard frog study is presented it should be clearly stated that no frogs or eggslarvae were found in the reference areas (p 4-13)

bull The text that describes comparisons between both the toxicity studies and the community evaluations and appropriately matched field references (p 4-27) should be revised to indicate that for the leopard frog study the field reference was limited to sediment not frogs collected from a reference pond

bull Although the text states that reference ponds were surveyed for eggs and larvae it does not indicate that in addition to no eggs or larvae being found at four of nine contaminated sites none were found at the reference sites (p 4-35)

bull Similarly the summary of female leopard frog reproductive fitness identifies all of the Housatonic River sites that were not gravid (did not have eggs mature enough for successful fertilization) (p 4shy30) It should also indicate that R2 (external reference) did not have any successful fertilization

325 Need to Acknowledge Additional Uncertainties While the ERA acknowledges some uncertainties associated with the amphibian studies (pp 4-70 4shy73 E-108-110) other critical uncertainties are not acknowledged For example there are uncertainties associated with the concentration-response analysis (eg ECsos ECaos) based on the poor fit of the data in the probit analysis Contrary to the statement that most endpoints followed a fairly smooth concentration-response (text box p 4-60) Table E4-2 indicates that only one of 11 of the ECsos presented (ie Phase III metamorph percent malformed based on comparisons with the lowest vernal pool sediment tPCB concentration) appears to be appropriately described by the probit analysis The other ECsos were described as (a) outside data range confidence limits increase (111) (b) probit model had poor fit to data confidence limits increase (111) (c) calculated with linear interpolation no confidence limits can be calculated (311) and (d) based on visual inspection of data (511) These uncertainties should be recognized

326 Need for Additional Information There are a number of issues on which we urge EPA to provide additional information in the next draft of the ERA

3-7

__

Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

__

Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

__

bull It appears that the reference WML-1 has been excluded from the calculation of NOAELs and LOAELs for Phase III metamorphs because of zero response at this concentration(Table E4-2) This exclusion is not warranted While the text refers to the tissue tPCB concentration for reference location WML-1 in the Phase III of the wood frog study as anomalous (eg p 4-52) no problems with data quality are reported that would indicate that the organism did not in fact have a tissue burden of 44 mgkg tPCBs As a result responses associated with this exposure level should be considered to represent part of the range of effects and all analyses of exposure and effect should include this reference site Statistical comparisons with a zero value are commonly made using a value marginally greater than zero (eg 000001)

bull Concentration-response relationships for each endpoint were evaluated using both (1) the most synoptic chemistry value paired with each toxicity endpoint (also referred to as vernal pool sediment) and (2) a combined data set used to generate a spatially weighted surface average (pp 4shy16 mdash 4-17) Given the variability in sediment concentrations the samples used in the laboratory toxicity study should not be assumed to be equivalent to the surface weighted average The synoptic (ie vernal pool) data reflect the actual tPCB concentrations measured in sediments used in the laboratory exposures and should thus should be used for analyses of the Phase I wood frog study which was conducted in the laboratory The surface weighted averages should be used for the analysis of Phase II and Phase III studies in which larvae and metamorphs were exposed in the field as they encompass the range of concentrations to which the growing larvae and metamorphs might have been exposed to The NOAELs LOAELs and point estimates for effects concentrations (eg LC50 and LC20) (Table E4-2) should be revised accordingly

bull Table E4-2 states that the reference site had no malformed specimens (Phase II metamorphs percent malformed) In fact Table E3-11 indicates that reference site WML-3 had 29 malformations

Moreover the toxicity threshold for wood frogs was derived based only on endpoints that showed effects The ERA states that if no discern[i]ble differences in effect levels across treatments were observed (ie inadequate range in response variable) the effects endpoint was not considered in the detailed statistical evaluation (p E-90) As a result as discussed in the next section the lack of PCB-related effects for key endpoints (ie mortality and metamorphosis) were not considered in the derivation of the effects threshold Consideration of the results for those omitted endpoints shows further that the sediment MATC of 1 mgkg is too low

We also note that although Appendix E presents tissue-based HQs for leopard frogs and wood frogs (pp E-96 - E-98) Section 12 of the ERA presents only sediment-based HQs (Figures 122-1 and p 12shy7) Tissue concentrations provide a more direct measure of exposure than do sediment concentrations and hence the tissue-based rather than sediment-based HQs should be used in Section 12

323 Need to Consider Additional Relevant Endpoints in Wood Frog Study As noted above in evaluating the results of the wood frog study two endpoints with clear ecological relevance ~ metamorphosis and mortality -- were screened out of the formal concentration-response modeling due to a lack of discern[i]ble differences in effect levels across treatments (p E-90) However these two endpoints integrate other effects (ie the most serious effect of malformations would be reduced metamorphosis and increased mortality) and should be carried through the

concentration-response evaluation If no concentration-response curve can be derived because there were no effects then the highest dose should be treated as a NOAEL for these endpoints the LC50

should be expressed as gt highest dose and both mortality and metamorphosis should be considered subsequently as part of the lines-of-evidence evaluation

324 Evaluation of the Leopard Frog Study EPAs leopard frog study receives the same overall weight (moderatehigh) as its wood frog study in the weight-of evidence-evaluation (Table 45-4 p 4-69) Considering the significant problems with the leopard frog study as detailed in GEs comments on this study (BBL Sciences et al 2003a) it should be accorded a low weight

Moreover the text does not consistently acknowledge that reference frogs for the leopard frog study were obtained from a biological supply company For readers unfamiliar with the underlying study this could lead to misinterpretations of the results presented The text should be modified to clearly represent this aspect of the leopard frog study as well as additional qualifications as follows

bull The first time the study design of the leopard frog study is presented it should be clearly stated that no frogs or eggslarvae were found in the reference areas (p 4-13)

bull The text that describes comparisons between both the toxicity studies and the community evaluations and appropriately matched field references (p 4-27) should be revised to indicate that for the leopard frog study the field reference was limited to sediment not frogs collected from a reference pond

bull Although the text states that reference ponds were surveyed for eggs and larvae it does not indicate that in addition to no eggs or larvae being found at four of nine contaminated sites none were found at the reference sites (p 4-35)

bull Similarly the summary of female leopard frog reproductive fitness identifies all of the Housatonic River sites that were not gravid (did not have eggs mature enough for successful fertilization) (p 4shy30) It should also indicate that R2 (external reference) did not have any successful fertilization

325 Need to Acknowledge Additional Uncertainties While the ERA acknowledges some uncertainties associated with the amphibian studies (pp 4-70 4shy73 E-108-110) other critical uncertainties are not acknowledged For example there are uncertainties associated with the concentration-response analysis (eg ECsos ECaos) based on the poor fit of the data in the probit analysis Contrary to the statement that most endpoints followed a fairly smooth concentration-response (text box p 4-60) Table E4-2 indicates that only one of 11 of the ECsos presented (ie Phase III metamorph percent malformed based on comparisons with the lowest vernal pool sediment tPCB concentration) appears to be appropriately described by the probit analysis The other ECsos were described as (a) outside data range confidence limits increase (111) (b) probit model had poor fit to data confidence limits increase (111) (c) calculated with linear interpolation no confidence limits can be calculated (311) and (d) based on visual inspection of data (511) These uncertainties should be recognized

326 Need for Additional Information There are a number of issues on which we urge EPA to provide additional information in the next draft of the ERA

3-7

__

Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

__

Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

concentration-response evaluation If no concentration-response curve can be derived because there were no effects then the highest dose should be treated as a NOAEL for these endpoints the LC50

should be expressed as gt highest dose and both mortality and metamorphosis should be considered subsequently as part of the lines-of-evidence evaluation

324 Evaluation of the Leopard Frog Study EPAs leopard frog study receives the same overall weight (moderatehigh) as its wood frog study in the weight-of evidence-evaluation (Table 45-4 p 4-69) Considering the significant problems with the leopard frog study as detailed in GEs comments on this study (BBL Sciences et al 2003a) it should be accorded a low weight

Moreover the text does not consistently acknowledge that reference frogs for the leopard frog study were obtained from a biological supply company For readers unfamiliar with the underlying study this could lead to misinterpretations of the results presented The text should be modified to clearly represent this aspect of the leopard frog study as well as additional qualifications as follows

bull The first time the study design of the leopard frog study is presented it should be clearly stated that no frogs or eggslarvae were found in the reference areas (p 4-13)

bull The text that describes comparisons between both the toxicity studies and the community evaluations and appropriately matched field references (p 4-27) should be revised to indicate that for the leopard frog study the field reference was limited to sediment not frogs collected from a reference pond

bull Although the text states that reference ponds were surveyed for eggs and larvae it does not indicate that in addition to no eggs or larvae being found at four of nine contaminated sites none were found at the reference sites (p 4-35)

bull Similarly the summary of female leopard frog reproductive fitness identifies all of the Housatonic River sites that were not gravid (did not have eggs mature enough for successful fertilization) (p 4shy30) It should also indicate that R2 (external reference) did not have any successful fertilization

325 Need to Acknowledge Additional Uncertainties While the ERA acknowledges some uncertainties associated with the amphibian studies (pp 4-70 4shy73 E-108-110) other critical uncertainties are not acknowledged For example there are uncertainties associated with the concentration-response analysis (eg ECsos ECaos) based on the poor fit of the data in the probit analysis Contrary to the statement that most endpoints followed a fairly smooth concentration-response (text box p 4-60) Table E4-2 indicates that only one of 11 of the ECsos presented (ie Phase III metamorph percent malformed based on comparisons with the lowest vernal pool sediment tPCB concentration) appears to be appropriately described by the probit analysis The other ECsos were described as (a) outside data range confidence limits increase (111) (b) probit model had poor fit to data confidence limits increase (111) (c) calculated with linear interpolation no confidence limits can be calculated (311) and (d) based on visual inspection of data (511) These uncertainties should be recognized

326 Need for Additional Information There are a number of issues on which we urge EPA to provide additional information in the next draft of the ERA

3-7

__

Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

__

Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

__

Derivation of the sediment MATC There is no documentation explaining how the sediment MATC of 1 mgkg tPCB (p 4-75) was calculated As discussed above we urge EPA to revise that MATC In addition the ERA should document the derivation of that value

Presentation of evidence of harm and magnitude of effects Within each developmental stage there are some measurement endpoints that show adverse effects and others that do not The table summarizing evidence of harm and magnitude of effects (Table 45-5 pp 4-71 - 4-72) does not have sufficient detail to accurately represent this variability which is important for the evaluation of the lines of evidence This problem could be remedied if the actual measurement endpoints used in the study (ie survival growth) are explicitly reported under each developmental stage rather than simply categorizing effects by developmental stage (eg hatchlinglate embryo life stages)

Presentation of methods and results of statistical tests The discussion of statistical analyses appears to be incomplete The main text (Section 44112 p 4-29) does not describe all of the statistical methods that were used in this study (eg magnitude of effects probit analysis) the results of which are discussed in Appendix E (Section E433) The main text should provide a discussion of all statistical analyses conducted that provide the basis for conclusions reached in this study Moreover descriptions of statistical analyses that were conducted are presented in two places in Appendix E (Sections E273 and E432) Appendix E should combine these two separate methods sections In addition the results of the statistical tests described in Sections E432 and E433 of the ERA are not presented in the statistical appendix (EI) as stated in the text (p E-92) As a result conclusions based on these tests cannot be verified Appendix EI should be modified to include the results of all statistical analyses

327 Extrapolation of Risks Downstream of the PSA The MATC for amphibians is based on tPCB concentrations in floodplain pool sediment This MATC is derived based on evaluations of early-life toxicity to wood frogs exposed to sediment with a range of tPCB concentrations either in the laboratory or in situ However as discussed in Section 262 extrapolations downstream of the PSA are not based on tPCB concentrations in sediments from floodplain pools but on spatially weighted soil tPCB concentrations throughout the 100-year floodplain due to a lack of vernal pool data downstream of Woods Pond (pp 12-15 E-107) GE believes that in addition to revising the MATC the ERA should either limit its assessment of risks downstream of the PSA to potential floodplain pools or acknowledge that there are insufficient data available to assess risks to amphibians downstream of the PSA

328 Error in the Text The text states that treatments with the highest sediment or tissue tPCB concentrations also had the highest percentages of malformed metamorphs (p E-80) In fact 8-VP1 had the highest rate of malformations but it did not have the highest sediment concentrations on either a mean or spatially weighted basis (Figure E3-35 p 59) The text should be adjusted accordingly

33 Fish The ERAs risk assessment for fish derives a variety of effects thresholds some based on the literature and some based on Phase I or Phase II of EPAs fish toxicity studies conducted by the US Geological

__

Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed

__

Survey (USGS) The lowest effect thresholds applied to the PSA are 14 mgkg for tPCBs (based on a literature review) and 21 ngkg for TEQs (based on the Phase II study)3 Lower thresholds are derived for trout (based on the Phase II study) and are applied downstream of Woods Pond However as discussed in this section GE has substantial concerns about the derivation of the literature-based toxicity thresholds and about the ERAs evaluation of the fish toxicity studies to establish effect levels In addition we urge EPA to provide additional information on the derivation of those thresholds to consider available fish population studies and to address certain additional uncertainties

331 No Basis for Assertion of Concordance Among Tissue Effects Thresholds The ERA states that there is good concordance in both the magnitude and types of effects among the various literature and site-specific-derived tissue effects thresholds (pp 5-20 5-44) In fact effect levels reported in the literature range by more than an order of magnitude and the associated endpoints are often very different GE recommends that these statements be removed from the report and a discussion regarding the substantial variability in the tissue effects concentrations both reported in the literature and derived from the USGS studies should be provided in its place This discussion should be developed as supporting text for use in a probabilistic analysis (see Section 3323 below) and should be carried through to the uncertainties assessment

332 Derivation of Literature-Based Toxicity Effects Thresholds Based upon a review of the literature effects thresholds were determined for warm water and cold water fish on both a tPCB and a TEQ basis We have a number of concerns with these thresholds based on the interpretation of the literature and the selection of studies that were used in this analysis Moreover given the range of reported effects thresholds and the variability in tPCB and TEQ concentrations in fish in the PSA a probabilistic analysis rather than the use of a single toxicity value would provide a more meaningful risk characterization for fish

3321 Lack of basis for tPCB threshold of 14 mgkg A range of effect levels from 153 to 125 mgkg was reported in the studies that were accepted for this ERA (Table F3-2) A single threshold value (14 mgkg) was then derived for use in the risk characterization from the lines-of-evidence assessment presented in Attachment F4 to Appendix F It was not possible to reproduce this value based on the calculation guidelines described on pages 4 and 5 of Attachment F4 The derivation of this value appears to be in error for several reasons as discussed below

First a fathead minnow reproduction study conducted by the USAGE (1988) was cited as a key reason for the selection of the threshold value of 14 mgkg Upon examination of this study it is clear that it does not meet the screening criteria in Table F3-1 for acceptance in this ERA One of the criteria for rejection of a study is that co-occurring contaminants are present (p 2 Attachment F4) The USAGE (1988) study is based on fish exposure to field-collected sediments from the Sheboygan Harbor Wisconsin As stated on the USEPAs Sheboygan River Area of Concern website (httpwwwepagovglnpoaocshebovganhtml) the sediments are contaminated with high concentrations of PCBs PAHs and heavy metals Based on the rejection criteria in Table F3-1 the USAGE study should be rejected for use in this ERA because of co-contamination

3 The ERA erroneously states on p 5-52 that the latter is based on a literature review and that the TEQ threshold for warm water fish based on the Phase II study is 43 ngkg These are reversed