Environmental Risk Assessment and Management from a Landscape Perspective (Kapustka/Environmental Risk) || Ecological Risk Assessment toward a Landscape Perspective

Download Environmental Risk Assessment and Management from a Landscape Perspective (Kapustka/Environmental Risk) || Ecological Risk Assessment toward a Landscape Perspective

Post on 06-Jun-2016

217 views

Category:

Documents

0 download

Embed Size (px)

TRANSCRIPT

  • 2ECOLOGICAL RISK

    ASSESSMENT TOWARD ALANDSCAPE PERSPECTIVE

    Lawrence A. Kapustka

    The fundamental concepts of risk assessment are imbedded in our cultural prehistory.Then of course the considerations were intimately linked to daily survival: Was itsafe to cross a river, attack a woolly mammoth, eat the camas bulbs, or enter theterritory of hostile neighbors in search food, shelter, and treasure? Scientific inquiryenabled improved understanding of connections between events and consequences.For example, efforts by Pasteur and Koch established a basis for managing bacterialcontaminants and thereby develop safeguards against diseases.

    The application of risk assessment and risk management to biological situationslikely grew out of the science of epidemiology. Epidemiology, the study of diseasesin populations (Schwabe et al. 1977), emerged as a formal discipline in the late1800s following a severe cholera epidemic in London. The cause of the epidemicwas traced to contaminated drinking water, and the solution was simple: Remove thepump handles from the contaminated wells. The process that was used to make thediagnosis and find the solution represented a new way of thinking, one that searchedfor patterns and traced linkages that could explain the observed phenomenon.

    But formal constructs of risk assessment as we know them today are relativelynew. Though at one level, the procedures appear to be simple and the math is generallyelementary, the execution of the procedures quickly becomes complicated. The manydecisions that must be made in setting up an assessment, though none individually mayseem very challenging, can become daunting with the interconnectedness of the suite

    Environmental Risk and Management from a Landscape Perspective, edited by Kapustka and LandisCopyright 2010 John Wiley & Sons, Inc.

  • 12 ECOLOGICAL RISK ASSESSMENT TOWARD A LANDSCAPE PERSPECTIVE

    of decisions. Perhaps as illustrated in the popular expose on the human psyche, Blink(Gladwell 2005), we are ill-equipped to address such complexities. Experts are easily,often unwittingly, diverted by their prejudices and can make monumental errors injudgment. The strong focus on chemical stressors, along with simplistic and outdatedexplanations of how ecological systems work, may indeed lead us to develop highlyprecise descriptions of risks that are precisely wrong. In the collection of chaptersin this book, we proffer the landscape and systems perspectives as improvements tothe risk approaches, especially when integrated into tools from the field of decisionscience. Mistakes will still be made, but hopefully fewer and with better chance forcorrections. To set the stage, I first examine the basic features of contemporary riskassessment.

    RATIONALE FOR RISK ASSESSMENT

    The origin of formal risk assessment can be traced to the insurance industry (Suter,2008). Actuarial tables aided the search for patterns of mortality in specific age groupsand provided clues to link behaviors and lifestyles to the patternsthe foundation ofinsurance premiums. The art of describing the occurrence of death or morbidity linkedto putative causal factors (epidemiology) could be used to forecast events (a form ofquantitative risk assessment) and design remedial actions. With the dawn of the age ofchemicals following World War II, efforts were made to link chemical contaminationin food and adverse health consequences. Approaches established by the early 1980sform the core of risk assessment as it is currently practiced (NRC 1983, US EPA1992, 1998).

    Our basic aversion to external risk, those occurring beyond our control, led author-ities in search of a number that represented zero risk, or at least a probability so lowthat statistical sampling would be unable to distinguish the value from zero. Theetiology of this number representing essentially zero risk was traced in a delightfulpaper (Kelly 1991) that details how the arbitrary value of one in a millionthat is,106 became a de facto safe threshold in human health risk assessments.

    Formal constructs for dealing with human health risk assessment were in placebefore ecological risk assessment (EcoRA) was developed, and they had great influ-ence on the procedures used to evaluate ecological risks. In many ways this wasunfortunate, because throughout the development of ecological approaches, there werepressures to establish a structure that paralleled the human health risk assessment pro-cess. There are many fundamental similarities, but also many differences. Perhapsthe greatest shortcoming arises from considering the target receptors (human or oth-erwise) at the organism level, which often divorces the subjects from the dynamicinteractions they really experience in their ecological setting. Separation of humanand ecological risk procedures, in addition to creating unnecessary compartmentation,led to two lexiconsoften having identical terms, but with different definitions orusage. This leads to communication challenges that become especially difficult for theend users of the risk information. When compartmentalized, separate risk assessmentsfor humans and for all ecological receptors can cause much frustration. Against this

  • ASSESSMENT TIERS 13

    backdrop, there is a challenge to develop a holistic approach that merges these twoparallel approaches into one integrated realm that could improve the usefulness ofthe entire effort (Kapustka et al. 2008; also see Chapter 8). A holistic assessment,by extension of the multiple interactions, demands an assessment with a landscapeperspective.

    Near-term and long-term environmental and socioeconomic effects of environ-mental planning options must be characterized and evaluated to understand both thebenefits and consequences of each option. A formal Environmental Risk Assessment(EnRA) can minimize unwanted or unexpected consequences by identifying thoseactions most likely to be harmful to humans or ecological resources and ranking theacceptable and unacceptable effects of the various options. Consideration of only short-term profits or benefits from the use of environmental resources will likely produceharmful long-term environmental consequences. Proper use of the risk assessmentprocess will identify threats to environmental resources and allow decision-makers toselect management options that have the least negative impact.

    A formal risk assessment process has several advantages as applied to environ-mental planning and management of hazards (Suter 1993):

    It can provide the quantitative basis for comparing and prioritizing risks. It can provide informed, science-based input for benefitcost analyses. By expressing results as probabilities, it acknowledges the inherent uncertainty

    in predicting future environmental states, thereby making the assessment morecredible.

    It separates the scientific process of estimating the magnitude and probabilityof effects from the process of choosing among alternatives and determining theacceptability of risks.

    The last point is clearly the most important argument in favor of the risk assess-ment process. Values, biases, and societal influences define the questions asked inthe risk assessment process and influence the management decisions. However, theprocesses for determining the threat from a proposed action and magnitude of theexposure to stressors are grounded in the sciences. Characterization of the probabil-ity that an adverse outcome will occur as a result of the exposure to the stressor inquestion also is based on interpretation of science-based facts. The results of a riskcharacterization should be stated as a probability that an event will occur, because theoccurrence of future effects in ecological systems cannot be predicted with certainty.This is not merely a limitation of the science. Rather, it is an acknowledgment of thevariable and chaotic patterns of ecological systems. A risk assessment can also providea series of probabilities that an adverse effect will occur under different scenarios.

    ASSESSMENT TIERS

    The assessment process generally is staged with the initial stages (i.e., scoping andscreening) designed to be quick and relatively inexpensive. The early assessment stages

  • 14 ECOLOGICAL RISK ASSESSMENT TOWARD A LANDSCAPE PERSPECTIVE

    Scoping

    Screening

    Definitive

    Possible

    PlausibleDe

    fault t

    o Emp

    irical

    Probable

    Exposure Assumptions

    Figure 2.1. Progression from default assumptions toward empirical evidence in risk assess-ment.

    use broad-brush assumptions that skew the outcome in a manner that minimizes thechances of making Type II errorsthat is, declaring a situation to be safe when itis not. These early stages are intended to narrow the focus of definitive assessments,if needed, onto the important questions. Basically, these different stages move fromhighly protective assumptions (e.g., ones that assume toxicity responses at the lowestconcentrations and realization of maximum exposures) to ones that more closely alignwith the real-world setting for the situations in question (Fig. 2.1, Table 2.1).

    A most important aspect of these scoping/screening efforts is that the triggers orbright lines relating to environmental concentration (or equivalent measurement ofmagnitude for other stressors) are to be used in a one-way test. That is, if the con-centration of a chemical of interest is below the threshold, then the risks are deemedto be in the de minimis zone and are dropped from further consideration (Fig. 2.2).However, if concentrations are above the threshold, then further evaluation may bewarrantedthat is, site-specific factors affecting bioavailability or other moderating

    Table 2.1. Degree of Rigor and Content in Risk Assessment Tiers

    Tiers Content

    Scoping (Tier 1) CoarseMinimum dat