risk assessment and management of drinking water pollutants in korea
TRANSCRIPT
~ Pergamon
PH: S0273-1223(97)00734-8
Waf. Sci. Tech. Vol. 36, No. 12, pp. 309-323, 1997.© 1997 IAWQ. Published by Elsevier Science Ltd
Printed in Great Britain.0273-1223/97 $17'00 + 0'00
RISK ASSESSMENT AND MANAGEMENTOF DRINKING WATER POLLUTANTS INKOREA
Yong Chung, Dongchun Shin, Seongeun Park,Yeongwook Lim, Yoonho Choi, Seongjoon Cho,Jeeyeon Yang, Mansik Hwang, Yeosin Park and Hyun Lee
Department ofPreventive Medicine and Public Health College ofMedicine, Institutefor Environmental Research, Yonsei University, c.p.a. Box, Seoul 120-752, Korea
Abstract
The contamination of drinking water supply is becoming an increasingly seriousproblem in Korea. In order to protect public health, there is a need to regulate drinkingwater pollutants. The purpose of this project, a national project for three years startingfrom 1992 to 1995, is to assess the health risk of pollutants in drinking water andrecommend guidelines and management plans for maintaining good quality of drinkingwater. This study was conducted to monitor 80 species of chemicals including volatileorganic compounds(VOCs), polycyclic aromatic hydrocarbons(PAHs), pesticides and metalsin six major rivers and their distribution system for drinking water in Korea, andevaluate health risk due to exposure to these chemicals through four main steps of riskassessment in drinking water. In hazard identification, 80 species of chemicals wereidentified by the US EPA classification system. In their steps of exposure assessment,sampling of raw, treated and drinking water from the public water supply system havebeen conducted from 1993 to 1995, and 80 chemicals were analyzed. In dose-responseassessment, cancer potencies, unit risk estimates and virtual safety doses of carcinogenswere obtained by TOX-RISK, and reference doses and lifetime health advisories ofnoncarcinogens were calculated. Finally, in the risk characterization of detected chemicals,health risk due to exposure to carcinogens(weight of evidence, A or B) such as vinylchloride, carbon tetrachloride, l,2-dichloroethane, benzen, l,l,l,2-tetrachloroethane,trihalomethanes(THMs), lead and arsenic of tap water in several cities exceeded 10.
5level.
We suggest that non-regulated chemicals such as vinyl chloride, carbon tetrachloride andl,2-dichloroethane should be monitored periodically and be regulated by the DrinkingWater Management Act. © 1997 IAWQ. Published by Elsevier Science Ltd
Key words: drinking water, risk assessment, risk management, volatile organiccompounds(VOCs), polycyclic aromatic hydrocarbons(PAHs), pesticides
309
310 Y. CHUNG et al.
1. Introduction
The evaluation and methodology in appropriate control of hazard for thousands of
chemicals holds its importance in preventive aspects. Health risk assessment is a process
of scientific estimation on the qualitative and quantitative effects that may occur when a
person is exposed to environmental hazards. The ultimate objective of risk assessment is
to provide scientific information for risk management, especially in policy drafting and in
presenting regulation polices with reliable communications among policy decision makers,
industry and publics(NRC, 1983; US EPA, 1990).
Interest in the risk assessment for environmental pollutants has been raised especially
for the drinking water safety since 1980 in Korea. While there has been insufficient
recognition of the concepts and their utility currently the situation calls for the safety
assessment and the urgent institutionalization of the mythodology.
This study has been carried out from 1993 to 1995, in order to develop risk
assessment and management for environmental pollutants in drinking water for the
purpose of preserving a safe environment and protecting human health in Korea.
This task is especially being planned for the development of risk-based management
in order to ensure water safety and provide technology in controlling the quality of
drinking water. This includes developing the methodology of health risk assessment for
controlling environmental pollutants and hazardous chemicals as well(IERY, 1993-1995).
2. Methods
2.1 Hazard identification
Volatile organic compounds(VOCs), polycyclic aromatic hydrocarbons(PAHs), pesticides
and metals were selected to be assessed in consideration of the drinking water quality
standards in Korea and Japan, the guidelines of the US Environmental Protection
Agency(US EPA, 1989) and World Health Organization(WHO, 1993).
The data for deleterious chemicals has been collected from the sources: they are
IRIS(Integrated Risk Information System, 1993), IRPTC(International Register of Potentially
Toxic Chemicals, 1994), TOMES plus(Toxicology Occupational Medicine & Environmental
Series, 1992), TOXLINE(1993), and Health Advisories(US EPA, 1990).
Eighty items were classified by weight of evidences of US EPA classification system
based on toxicological information for animal and human studies, in vivo or in vitro assay.
Drinking water pollutnats in Korea
2.2 Exposure assessment
The samples of raw and treated water at water treatment plants and tap water from
individual households were collected and analyzed for the concentration of chemicals in 6
cities(Seoul, Pusan, Taegu, Taejon, Kwangju and Inchon) in March and June 1993-1995.
VOCs, PAHs and pesticides were analyzed by GC/MSD(US EPA, 1990) and metals
were analyzed AA or ICP instruments.
Also, we surveyed patterns of drinking water intake, water use rates and exposure
parameters related to water use in Korea by health questionnaire and diary.
Lifetime average daily exposure(LADE) of contaminant concentration in drinking
water was calculated by assuming the healthy adult conditions such as 60kg of body
weight, 70 years of lifetime expectancy and 2L of daily drinking water intake as
representative value of Koreans.
LADE(mg/kg/day) = Concentration(mg!L)*2L!day(90percentile)60kg
2.3 Dose-response assessment
Dose-response assessment for carcinogens was proceeded through two steps: dose
scaling from animal to human and extrapolation from high-dose to low-dose, which were
used by Multistage, Weibull, log-normal and Mantel-Bryan model in TaX-RISK package.
Consequently, carcinogenic potency(ql*), unit risk(UR) and virtual safety dose(VSD) were
estimated(Anderson et al., 1983).
The lifetime health advisory(LHAs) of noncarcinogens was calculated from the
Reference-Dose(RfD) based on the oral chronic No-Observed-Adverse-Effect-Level(NOAEL)
or Lowest-Observed-Adverse-Effect-Level(LOAEL).
2.4 Risk characterization
The excess cancer risks of carcinogens were calculated from the exposure
concentration and the unit risks estimated by dose-response assessment. The excess cancer
risk, less than 10.5 was regarded as the acceptable level.
For noncarcinogens, hazard quotient was estimated by LADE/RID or contaminant
concentration/lifetime health advisory. The hazard quotient, less than 1 was regarded as
the acceptable level of noncarcinogens.For the multi-route exposure of trihalomethanes(THMs) including chloroform, bromo-
311
312 Y. CHUNG et al.
dichloromethane, dibromochloromethane and bromoform, the excess cancer risks were
calculated for multipathway through oral intake, inhalation and dermal contact using
Monte-Carlo simulation in Crystal Ball package(Jo et al., 1990, Mckone and Bogen, 1992)
3. Results
3.1 Weight of evidence of drinking water pollutants
The selected substances in this study was assigned on the carcinogen classification by
the US EPA shown in Table 1. The selected substances were categorized in 45%
carcinogens and 55% noncarcinogens.
For the 80 species of assigned chemicals, toxicological profile and exposure database
have been compiled in Korean version. The toxicological profile includes structure,
pharmacokinetics, animal and human data, and the exposure database involves physical
and chemical properties, utility, environmental fate, exposure parameters, analytic method,
water quality and standard or guideline of individual chemical.
Table 1. Hazard classification of selected chemicals
Classifica Human Probable human Possible human Not c1assihable Evidence of Nolion carcinogen carcinogen carcinogen as to human noncarcino~en for
(A) (B) (C) carcinogen (0) human E) information
B~W~r-Benzo a anthracene Anthracene
PAHs Benzo fluoranthene Benzo(g,h,i)perylene
(13) Benzo k fluoranthene Fluorene AcenaphtheneChrysene PhenanthreneOibenzo(a,h)anthracene PyreneIndeno(1,2,3-cd)pyrene1,2-dlchloroethane 1,l-dichloroethyleneCarbontetrachlonde DibromochloromethaneTnchloroethylene l,l,l-trichloroethane
VOCs & Benzene l,l-dichloroethane Chlorobenzenesolvents Vint
Tetrachloroethylene 1,1,2-trichloroethane EthylbenzeneChloroform(22) c loride Bromodichloromethane 1,1,1,2-tetrachloroethane 1,2-dichlorobenzene
Bromoform 1,1,2,2-tetrachloroethane TolueneOichloromethane m,p-Xylene
AluminiumBariumCadmium
Metals Beryllium Chromium Iron(13) Arsenic Lead Copper Nickel SodIum,Manganese
MercurySeleniumZinc
ChIoro- 2,4,6-trichlorophenol 2-ehlororohenolphenols(4) Pentachloroplienol 2,4-dich orophenol
Carbofuran Chlorfen-CattafolAldnn Aldicarb eh orpyrifos vinphos
Pesticide Dieldrin 2,4-D Diazinon Endosulfans Heptachlor Parathion Endrine Disulfoton Fenitrothion
(19) Methoxychlor EPN FenthionHeptachlor epoxide
2,4,5-T Lindane Omethoate
Malathion PhenthoatePropachlor Sllvex
Drinking water pollutnats in Korea
3.2 Exposure assessment
VOCs and metals were detected from most samples while pesticides and PAHs were
not detected in all samples(Table 2 & Table 3).
The concentration of VOCs showed variation by water type. Individual THMs were the
highest in treated water, while most of industrial solvents such as benzen were rather less
in treatment plants and tap water at home.
PAHs and Pesticides were not detected because the sensitives of analytical detection
limit were too low to be detected.
Table 4 shows VSD of carcinogen corresponding to de minimis risk(lOl of detected
chemicals and proportion of detected number and exceeding VSD to all samples. Benzene,
carbon tetrachloride, individual THMs and l,2-dichloroethylene were detected in drinking
water higher than 30% of VSD.
Table 2. Mean concentrations of VOCs by water type (unit: fJ.g/L)
~Raw water Treated water Orinking water Oetection
VOCs Mean (Min, Max) Mean (Min, Max) Mean (Min, Max) limit
Vinyl chloride NO (NO, NO) 0.040 (NO, 0.48) 0.014 (NO, 0.25) 0.013
I,l-dichloroethylene 0.012 (NO, 0.15) 0.022 (NO, 0.12) 0.019 (NO, 0.38) 0.012
Dichloromethane 0.048 (NO, 0.58) 0.039 (NO, 0.47) 0.008 (NO, 0.23) 0.03
l,l-dichloroethane NO (NO, NO) NO (NO, NO) NO (NO, NO) 0.04
Chloroform 0.788 (NO, 4.31) 17.50 (NO, 61.15) 10.512 (NO, 57.50) 0.10
1,2-dichloroethane 0.006 (NO, 0.03) 0.004 (NO, 0.02) 0.019 (NO, 0.53) 0.01
Benzene 2.961 (NO, 10.52) 2.680 (NO, 13.51) 2.116 (NO, 25.77) 0.04
Carbon tetrachloride 0.641 (NO, 1.71) 0.584 (NO,2.08) 0.438 (NO, 2.24) 0.21
Trichloroethylene 0.015 (NO, 0.18) 0.047 (NO, 0.48) 0.009 (NO, 0.16) 0.01
Bromodichloromethane NO (NO, NO) 6.164 (NO, 28.41) 3.960 (NO, 20.78) 0.08
Toluene 9.410 (1.09, 33.35) 8.845 (0.18, 35.54) 5.156 (NO, 28.22) 0.11
1,1,2-trichloroethane 0.010 (NO, 0.06) 0.012 (NO, 0.06) 0.011 (NO, 0.10) 0.01
Dibromochloromethane NO (NO, NO) 1674 (NO, 5.81) 1.184 (NO, 6.63) 0.03
Tetrachloroethane NO (NO, NO) NO (NO, NO) NO (NO, NO) 0.14
Chlorobenzene NO (NO, NO) NO (NO, NO) NO (NO, NO) 0.04
Ethylbenzene 1.881 (NO, 10.60) 2.047 (NO, 11.52) 0.634 (NO,7.79) 0.01
m,p-xylene 4.815 (NO, 25.38) 4.757 (NO, 24.68) 1.843 (NO, 16.47) 0.05
Bromoform 0.173 (NO,2.06) 0.188 (NO, 0.65) 0.120 (NO, 0.69) 0.12
1,1,2,2-tetrachloroethane NO (NO, 0.01) NO (NO, NO) 0.001 (NO, 0.01) 0.01
1,2-dichlorobenzene NO (NO, NO) NO (NO, NO) NO (NO, 0.01) 0.01
313
314 Y. CHUNG et al.
Table 3. Mean concentrations of metals by water type (unit: fjg!L)
~Raw water Treated water Drinking water Oetection
Metals Mean (Min, Max) Mean (Min, Max) Mean (Min, Max) limit
Aluminium 0.Q7 (NO, 0.57) 0.05 (NO, 0.31) 0.061 (NO, 0.47) 0.001
Arsenic 0.002 (NO, 0.02) 0.01 (NO,0.20) 0.001 (NO,O.Ol1) 0.001
Bariwn 0.012 (NO, 0.03) 0.012 (0.005, 0.026) 0.010 (0.002, 0.039) 0.001
Beryllium NO (NO, NO) NO (NO, NO) NO (NO, NO) 0.004
Cadmiwn NO (NO, 0.(02) NO (NO, NO) NO (NO, 0.(02) 0.001
Chromiwn 0.003 (NO, 0.048) 0.001 (NO, 0.007) NO (NO, 0.(07) 0.001
Copper 0.02 (NO, 0.25) 0.005 (NO, 0.04) 0.010 (NO, 0.025) 0.001
Iron 0.31 (NO, 2.10) 0.05 (0.01, 0.25) 0.083 (0.001, 1.000) 0.001
Lead 0.003 (NO, 0.035) 0.001 (NO, 0.012) 0.001 (NO, 0.015) 0.001
Managanese 0.093 (NO, 1.30) 0.01 (NO, 0.07) 0.012 (NO, 0.130) 0.001
Mercury 0.01 (NO, 0.14) 0.02 (NO, 0.26) 0.007 (NO, 0.836) 0.001
Nickel 0.002 (NO, 0.009) 0.001 (NO, 0.001) 0.002 (NO, 0.009) 0.002
Selenium NO (NO, NO) NO (NO, NO) NO (NO, NO) 0.001
Sodiwn 10.06 (NO, 34.00) 18.65 (2.40, 159.0) 8.584 (0.005, 35.(0) 0.001
Zinc 0.04 (NO, 0.48) 0.02 (NO, 0.15) 0.046 (0.001, 0.58) 0.001
Table 4. The Virtual Safety Dose(VSD) of carcinogen and proportion of exceeding VSD
Exposure assessment (n=102)Carcinogens VSD(JLg/L)* Proportion of Prodiortion of
detected number(%) excee ing VSD (%)Vinyl cWoride 0.014 35 35Arsenic 0.017 48 0Benzene 1.035 76 63HeptacWor epoxide 0.002 0 0Aldrin 0.002 0 0Beryllium 0.002 0 0HeptacWor 0.003 0 0Carbon tetracWoride 0.065 59 59Benzo(a)pyrene 0.166 6 0PentacWorophenol 0.229 0 0BromodicWoromethane 0.241 79 75Lead 0.766 60 0CWoroform 1.041 77 71Tetrachloroethylene 1.236 14 12TricWoroethylene 3.111 32 1OicWoromethane 2.392 51 48Bromoform 2.408 37 82,4,6-tricWorophenol 2.738 0 0Dieldrin 0.002 0 0l,2-dicWoroethane 0.779 59 251,l-dicWoroethylene 0.039 44 401,I,I,2-tetracWoroethane 1.048 13 7DibromocWoromethane 0.357 62 34I, 1,2-tricWoroethane 0.445 18 61,1,2,2-tetracWoroethane 0.098 8 0l,l-dicWoroethane 19.998 50 0Parathion - 0 -
*VSD(Vrrtual safety dose): Concentration corresponding to de minimis risk(10~) calculated
Drinking water pollutnats in Korea
3.3 Dose-response and Risk characterization
3.3.1 Risk estimation of carcinogens
Carcinogenic potencies (ql*) and unit risks were estimated by Multistage, Weibull,
log-normal and Mantel-Bryan model in TOX-RISK(Ver 3.1) package. Virtual safety dose
(VSD) and unit risks(UR) estimated by multistage model are shown in Table 4 and Table
5.In general, every model for animal data was very linear in applicability. Especially,
multistage and Weibull models were more reliable for the low doses. Since Mantel-Bryan
and log-normal models have a tendency to draw sublinear curves at low doses, it seems
that they show the relatively lower unit risks for low doses than other models.
Accordingly, the unit risk calculated from by multistage model is appropriate for most
substances(Cotruvo, 1988, Hanes and Wedel, 1985).
Unit risk and VSD of the chemicals which could not obtain raw data for
dose-response were adopted from IRIS(Integrated Risk Information System, 1993) and
those of PAHs were estimated by TEFs(Toxic Equivalent Factors) method(Ian et al., 1992).
For carcinogens, excess cancer risks were calculated by contaminant average
concentration and unit risk of 95% upperbound estimated by Multistage model.
In risk characterization of detected chemicals, health risk due to carcinogens such as
vinyl chloride, carbon tetrachloride and 1,2-dichloromethane, chloroform, benzene and
arsenic of drinking water in several cities exceeds lO-slevel(Table 5).
3.3.2 Risk estimation of noncarcinogens
Table 6 shows reference dose(RfD) and lifetime health advisories(LHAs) for
noncarcinogens.The values of RID and lifetime health advisories depend upon the selection of
NOAEL or LOAEL at the endpoint of adverse effects. The NOAEL or LOAEL was
selected from the sensitive and specific effects(Michael and Jerry, 1983, Michael et al.,
1992).For noncarcinogens hazard quotient was estimated by LADE/RfD or contaminant
concentration/lifetime advisory. The hazard quotient being less than one regarded as
acceptable level.Hazard quotients of organic and inorganic noncarcinogen did not exceed 1.
315
316 Y. CHUNG et (//
Table 5. The Risk estimates and guidelines of carcinogenic pollutants
Upper bound· Excess cancer risk
Chemical Unit risk Arithmetic Detection(/Lg/L),l Median
Limit-mean
Vinyl chloride 7.36 x 10" - 6.84 x 10" -
Arsenic 5.83 x 10" - 5.83 x 10" -
Benzene 9.67x 10'1 1.48 x 10'" 3.74 x 10'" -
Heptachlor epoxide 6.43 x 10'" - - 1.29XI0'"
Aldrin 4.49 x 10'" - - 1.80 X10-1
Beryllium 4.28 x 10'" - - 1.71 x 10'"
Heptachlor 3.94 x 10'" - - 5.00 x 10'"
Carbon tetrachloride 1.52 x 10" 8.19 x 10'" 1.99 x 10" -Benzo(a)pyrene 6.02 x 10'" - 6.02 x 10'Y -
Pentachlorophenol 4.38 x 10'" - - 2.19x 10"
Bromodichloromethane 4.15 x 10'" 7.22 x 10'" 2.80X 10" -Lead 1.30 x 10'" - 1.30 x 10'" -Chloroform 9.60 x 10'1 6.45 x 10'" 1.92 x 10" -Tetrachloroethylene 8.09 X 10'1 - 8.90XI0"" -Trichloroethylene 6.15 X 10.1 - 2.09x 10'1 -Dichloromethane 4.18 x 10'1 7.94 x 10"" 1.62 x 10'" -
Bromoform 4.15 X 10'1 - 3.61 X10'1 -
2,4,6-trichlorophenol 3.65 x 10'1 - - 1.83 x 10'"
Dieldrin 5.33 x 10'" - - 2.67 x 10'"
1,2-dichloroethane 1.28 x 10'" 8.99 x 10"" 2.80xl0'" -l,l-dichloroethylene 2.57 x 10" - 1.06 x 10" -1,1,1,2-tetrachloroethane 9.54 X 10'1 - 1.81 X10" -Dibromochloromethane 2.80 x 10'" 1.40 X 10'1 9.04 X10'" -1,1,2-trichloroethane 2.25 x 10'" - 3.15 x 10'1 -1,1,2,2-tetrachloroethane 1.03 x 10" - 2.06 x 10'" -l,l-dichloroethane 5.00x 10'" 5.00 x 10'IV 7.85 X10'" -Parathion - - - -• 95% upper bound urut fisk obtamed by TOX-RISK package (Multistage model)
** excess cancer risk was calculated by substitution with analytical detection limit
Drinking water polIutnats in Korea 317
Table 6. Health advisories of noncarcinogens
NOAEL orUncertainty
Reference dose LifetimeNoncarcinogen LOAEL ; RID
OWELfactor; UF (mg/L)
RSC HAs(mg/kg/ day) (mg/ kg/day) (mg/L)
2-Chlorophenol 5(N) 1000 0.005 0.175 20 0.03550(L)
1,2-0ichlorobenzene 85.7(N) 1000 0.086 3.01 20 0.602Chlorobebzene 27.25(N) 1000 0.02 0.7 20 0.14Ethylbenzene 54.5(L) 1000 0.097 3.395 20 0.679
97.1(N)Monochlorobenzene 40(N) 1000 0.040 1.4 20 0.28Toluene 1130mg/m3(N)1 100 0.346 12.11 20 2.4221,1-0ichloroethylene 9(L) 1000 0.009 0.315 20 0.0631,1,1-Trichloroethane 1365mg/m\N)2 1000 0.035 1.225 20 0.245Xylene 337mg/m3(N)3 1000 0.06162 2.1567 20 0.43134Aldicarb 0.02(L) 100 0.0002 0.007 20 0.0014Carbofuran 0.5(N) 100 0.005 0.175 20 0.035Oisulfoton 0.04(N) 1000 0.00004 0.0014 20 0.00028Endrin 0.0045(N) 1000 0.0000045 0.0002 20 0.00004EPN O.Ol(N) 1000 0.00001 0.00035 20 0.00007Methoxychlor 5.0(N) 100 0.05 1.75 20 0.352,4,5-T 3(N) 300 0.01 0.35 20 0.07
10(L)2,4-dichlorophenol 0.3 100 0.003 0.105 20 0.0212,4-0 1.0(N) 100 0.01 0.35 20 0.07Captafol 2(L) 1000 0.002 0.07 20 0.014Chloropyrifos 0.03 10 0.003 0.105 20 0.021Oiazinon 0.009 100 0.00009 0.00315 20 0.00063Lindane 0.33 1000 0.00033 0.01155 20 0.00231Malathion 0.23 10 0.0230.805 20 0.161Propachlor 13.3 1000 0.0132 0.462 20 0.0924Cadmium 0.005(L) 10 0.00050.0175 25 0.004375ChromiumVI 2.41(N) 100(5) 0.00482 0.168 71 0.11928Mercury 0.05mg/ kg/ inj 1000 0.0001580.00553 20 0.001106Barium 0.21 3 0.07 2.45 10 0.245Manganese 0.005 1 0.005 0.175 10 0.0175Selenium 0.015 3 0.0050.175 10 0.0175Zinc 1.0(L) 3 0.33 11.55 10 1.155Nickel 5 300 0.0167 0.5845 10 0.05845Anthracene 1,000 3,000 0.3 10.5 20 2Fluorene 125 3,000 0.04 1.4 20 0.28Acenaphthene 175 3,000 0.06 2.1 20 0.42
uncertainty factor x daily drinking water intake
NOAEL or LOAEL
NOAEL or LOAEL x body weightHealth Advisories ; HAs
Reference Dose ; RIDuncertainty factor ( or x additional factor )
RID x 60kgDWEL ( Drinking Water Equivalent Level) = ---------
2L 1 day
Lifetime Health Advisories = DWEL x Relative Source Contribution(RSC)
Total Absorbed Dose' TAD = NOAEL or LOAEL (inhalation animal data) x exposure time x daily breathing, rate per day x 5/7 x absorption fration 1 70kg
1 inhalation animal data NOAEL 1130 mg/rl\3 -> TAD 346 mg/kg/day2 inhalation animal data LOAEL 1365 mg/m -> TAD 35 mg/kglday3 inhalation animal data NOAEL 337 mg/m3
••> TAD 61.62 mg/kg/day
318 Y. CHUNG et al.
3.3.3 Characterization of health risk by multi-route exposure analysis of THMsusing Monte-Carlo simulation
This study was examined on the range of plausible health risks associated with daily
exposure to contaminant concentration of chloroform, bromodichloromethane,
dibromochloromethane and bromoform of drinking water using Monte-Carlo simulation,
the available data for each exposure parameter were evaluated with respect to distribution
types, and mean, standard deviation, maximum and minimum value were identified and
probablity distributions of risk were obtained(Andelman, 1985; Brown, 1984).
The cancer risks of trichloroethylene and perchloroethylene by inhalation route were
higher than those of ingestion and dermal contact route(Fig. 1). Cancer risk at 95
percentile of bromoform was over 10-5 level and those of chloroform,
dibromochloromethane, dichlorobromomethane were over 10-4 level. Total cancer risks of
three VOCs at 95 percentile were higher than those calculated by the formal risk
assessment of US EPA which was applied only for oral ingestion, considering the
designated water intake amount of 2L/day/person and the body weight.
Inhalation
•
3.7%
Ingestion Inhalation96.3% 86.3%
Ingestion13.7%
Inhalation88.5%
Ingestion11.5%
Vinyl chloride Trichloroethylene Perchloroethylene
Figure 1. Lifetime-average-daily-exposure-dose(95th value) with Monte-Carlo
simulation of three VOCs in drinking water
3.5 Risk management
According to the weight of evidence and estimated excess cancer risk of pollutants,
risk based priority groups were recommended to each of the five levels for the
management of drinking water safety(Table 7).
Drinking water pollutnats in Korea
Non-regulated carcinogenic pollutants such as carbon tetrachloride, vinyl chloride,
1,2-dichloroethane should be monitored periodically and be regulated in the drinking
water guidelines.
Based on the above results and MeL of carcinogen by EPA and WHO, the guidelines
of carcinogenic pollutants to be recommended by prioritization and changecl their
permissible concentration ranges by in the Drinking Water Management Act are suggested
in Table 7, 8.
Table 7. Prioritization of selected pollutants
Group Chemicals Classification
ArsenicBenzene
Class 1 Bromodichloromethane Weight of evidence 6f B andCarbon tetrachloride Excess cancer risk 10'ChloroformVinyl chloride
Dichloromethane Weight of evidence BandClass 2 1,2-dichloroethane Excess cancer risk 10-6Lead
Benzo(a)pyreneBromoform Weight of evidence Band1,1-dichloroethylene Excess cancer risk < 10.7 or
Class 3 Dibromochloromethane W$ight of evidence C andl,l,1,2-tetrachloroethaneTetrachloroethylene
10' < Excess cancer risk
Trichloroethylene
AldrinBe~lliumDie drin W$ight of evidence Band
Class 4 Heptachlor 10' < Excess cancer riskHeptachlor el:0xidePentachlorop enol2,4,6-trichlorophenol
1,1-dichloroethane Weight of evidence C ~d
Class 51,1,2,2-tetrachloroethane Excess cancer risk < 10 or1,1,2-trichloroethane Weight of evidence DMercury
319
320 Y. CHUNG et al.
Table 8. The guidelines of carcinogenic pollutants to be recommended and their permissible
concentration ranges
PriorityCarcinogenic Pollutant
MCL(proposed) Guideline(flg/L)
group 10-j 10-1 10"' 10ol> US EPA WHO
Carbon tetracWoride 6 0.6 0.06 5 2Class 1
5Vinyl cWoride 1 0.1 0.01 2
Class 2 1,2-dicWoroethane 70 7 0.7 5 30
Benzo(a)pyrene 10 1 0.1 0.2 0.7
Class 3 1,1,1,2-tetracWoroethane 100 10 1 - -1,1-dicWoroethylene 3 0.3 0.03 7 30
Aldrin 0.2 0.02 0.002 - 0.03
Beryllium 2 0.2 0.02 0.002 4 -Dieldrin 0.2 0.02 0.002 - 0.03
Class 4 HeptacWor 0.3 0.03 0.003 0.4 0.03
HeptacWor epoxide 0.2 0.02 0.002 0.2 -PentacWorophenol 20 2 0.2 1 92,4,6-tricWorophenol 270 27 2 - 0.03
Table 9. The guidelines of carcinogenic pollutants to 1:Je changed their permissible concentration
range
Priority MCL GuidelinesCarcinogenic Pollutant US
Group 10-j 10-1 10"' 10ol> Korea WHOEPA
Arsenic 10 1 0.1 0.01 5050 10Benzene 100 10 1 10 5 10
Class 1BromodicWoromethane 20 2 0.2 100(T) 100(T) 60CWoroform 100 10 1 100(T) 100(T) 200
Class 2DicWoromethane 230 23 2 20 5 20Lead 70 7 0.7 50 15 10Bromoform 240 24 2 100(T) 100(T) 100
Class 3DibromocWoromethane 35 3 0.3 100(T) 100(T) 100TetracWoroethylene 120 12 1 10 5 40TricWoroethylene 310 31 3 30 5 70
T: THMs(current standard level: lOOugjL)
Drinking water pollutnats in Korea
Table 10. The non-earcinogenic pollutants to be changed their guidelines and their pennissibleranges of concentration
Noncarcinogenic Acceptable levelGuideline(mg/L)
pollutant (Proposed) KoreaUS
EPAWHO
Aldicab below 1 p.g/L - 7 10
Carbofuran below 30 p.g/L - 40 52,4-D below 60 p.g/L - 70 30
Methoxychlor below 30 p.g/L - 40 20
Barium below 0.2 p.g/L - 2 0.7
Nickel below 0.05 p.g/L - 0.1 0.02
Ethylbenzene 0.8 mg/L 0.3 0.7 0.3
Toluene 2 mg/L 0.7 1 0.7
1,1, I-trichloroethane 8 mg/L 0.1 0.2 2
m,p-xylene 0.8 mg/L 0.5 10 0.5
Diazinon below 0.5 mg/L 0.02 - -Malathion below 0.1 mg/L 0.25 - -Cadmium below O.OOlmg/L 0.01 0.005 0.003
Chromium below 0.01 mg/L 0.05 0.1 0.05
Manganese below 0.01 mg/L 0.3 - 0.5
Mercury below O.OOlmg/L N.D.* 0.002 0.001
4. Conclusion
This study evaluated human health risk of 80 species of drinking water pollutants in
Korea by appling four main steps of risk assessment and suggested the guidelines.
In risk characterization of detected chemicals, the cancer risk of pollutants such as
vinyl chloride, carbon tetrachloride, chloroform, benzene, 1,1-dichloroethylene, bromo
dichloromethane, 1,1,1,2-tetrachloroethane, and arsenic of drinking water in several cities
exceed 10-5 level. For 31 noncarcinogen species, reference doses(RfD) and health
advisories(HAs) of lifetime acceptable levels were calculated and hazardous
quotients(contamination concentration/Lifetime HAs) of them were less than one, which
meant "acceptable".According to the weight of evidence and estimated excess cancer risk of pollutants,
risk-based priority groups were recommended to each of five levels for the management
of drinking water safety. Non-regulated carcinogenic pollutants such as carbon
tetrachloride, vinyl chloride, 1,2-dichloroethane should be monitored periodically and be
321
322 Y. CHUNG t't al.
regulated in the drinking water guidelines. Especially, through the exposure analysis of
new hazardous substances, risk assessment should be undertaken, and risk management
be considered.
Further researches should be continued in order to improve the process of risk
assessment and risk management of drinking water quality in Korea.
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