title: Health risk assessment on residents exposed to chlorinated hydrocarbons contaminated in groundwater of a hazardous waste site.
abstract: We conducted this study to estimate residents' chronic hazard and carcinogenic risk in a groundwater-contaminated community after on-site remediation in Taiwan during 1999-2000. We followed guidelines for assessing hazardous waste sites of the U.S. Environmental Protection Agency (EPA) and used empirically measured contaminant levels and exposure parameters to perform health risk assessment on seven chlorinated hydrocarbons. We measured groundwater concentrations of vinyl chloride, tetrachloroethylene, trichloroethylene, 1,1-dichloroethylene, 1,1,1-trichloroethane, cis-1,2-dichloroethylene, and 1,1-dichloroethane in 49 off-site residential wells by gas chromatography/mass spectrometry. Exposure parameters were mainly derived from our field survey of 382 residents, and partially from U.S. EPA default values. Total exposure dose estimation included routes of inhalation during showering and dermal absorption of showers and other activities involved with hand-water contacts. The ingestion route of water was not included because most residents drank boiled water with negligible contaminants. We calculated a hazard index (HI) for all seven chlorinated hydrocarbons and carcinogenic risks for known human carcinogen of vinyl chloride and probable human carcinogens of tetrachloroethylene and trichloroethylene, which had the same target organ, the liver. The HI values for reasonable maximal exposure (RME) and average exposure were 14.3 and 0.2, respectively. The cancer risks based on RME and average exposure (in parentheses) for vinyl chloride, tetrachloroethylene, and trichloroethylene were 8.4 x 10(-6) (7.3 x 10(-9)), 1.9 x 10(-4) (1.3 x 10(-7)), and 1.4 x 10(-4) (1.2 x 10(-6)), respectively. We applied Monte Carlo simulations to the sensitivity analysis, which showed that the contaminant levels, exposure duration, and time for showers were major determinants of health risks. We concluded that the contaminated groundwater was still unsafe for use even after the contaminated site underwent remediation by extraction and treatment in 1997.
authors.affiliation: Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei.
authors.forename: Lukas Jyuhn-hsiarn
authors.initials: LJ
authors.lastname: Lee
authors.forename: Chang-Chuan
authors.initials: CC
authors.lastname: Chan
authors.forename: Chih-Wen
authors.initials: CW
authors.lastname: Chung
authors.forename: Yee-Chung
authors.initials: YC
authors.lastname: Ma
authors.forename: Gan-Shuh
authors.initials: GS
authors.lastname: Wang
authors.forename: Jung-Der
authors.initials: JD
authors.lastname: Wang
mesh_terms: D001494:Baths; D002273:Carcinogens / Q000009:adverse effects* / Q000032:analysis; D004781:Environmental Exposure; D004784:Environmental Monitoring; D008401:Gas Chromatography-Mass Spectrometry; D006256:Hazardous Waste; D006801:Humans; D006843:Hydrocarbons, Chlorinated / Q000009:adverse effects* / Q000032:analysis; D009369:Neoplasms / Q000209:etiology; D011634:Public Health; D018570:Risk Assessment; D012989:Soil Pollutants / Q000009:adverse effects* / Q000032:analysis; D013624:Taiwan; D014874:Water Pollutants, Chemical / Q000009:adverse effects* / Q000032:analysis; D014881:Water Supply
chemical_list: D002273:Carcinogens; D006256:Hazardous Waste; D006843:Hydrocarbons, Chlorinated; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical