Update: March 1996
Current Massachusetts Regulatory Limit
MMCL = 0.005 mg/L. ORS has adopted the MCL published by the U.S. EPA as part of the Phase V rule (57 FR 31776).
Federal Regulatory Limit
The MCL for 1,1,2-trichloroethane is based on its detection limit of 0.005 mg/L. The MCLG is equal to 0.003 mg/L.
Basis for Criteria
The MCLG of 0.003 mg/L for 1,1,2-trichloroethene has been set based on noncancer effects. The MCL has been set at the PQL for 1,1,2-trichloroethane of 0.005 mg/L because the U.S. EPA believes that the PQL is as close to the MCLG as is feasible. The MCLG of 0.003 mg/L is based on the RfD presented below and assumes that a 70 kg adult ingests 2 L/day of water. The MCLG incorporates a relative source contribution factor of 0.2 and an uncertainty factor of 10 to account for potential carcinogenicity.
The derivation of the MCLG for 1,1,2-trichloroethane is consistent with U.S. EPA's process for deriving an MCLG for a Group C carcinogen (as described on page 46949 of 50 FR 46936). If available, the primary option is to set the MCLG based on noncarcinogenic endpoints and to account for potential carcinogenicity by applying an additional uncertainty factor of up to 10 to the final value. If adequate noncancer data are not available to permit the derivation of an RfD, the second option is to set the MCLG to fall within an excess lifetime cancer risk (ELCR) range of 10-5 - 10-6. Since adequate noncancer data are available for 1,1,2-trichloroethane, the MCLG for this chemical is based on noncancer effects. U.S. EPA also determined that the MCLG of 0.003 mg/L corresponds to a theoretical cancer risk limit of 1 x 10-5.
RfD: 4 x 10-3 mg/kg/day
UF: 1000 (10 intraspecies; 10 intraspecies; 10 subchronic to chronic)
MF: 1 Confidence: Medium
1,1,2-trichloroethane has been shown to target the liver and kidney in laboratory animals. Subchronic studies in mice (White et al. 1985; Sanders et al., 1985), in which 1,1,2-trichloroethane was administered in the diet at concentrations of 0, 20, 200 or 1,000 ppm of 1,1,2-tricloroethane in water, indicated adverse effects in livers of mid- and high-dose males and high-dose females. A NOAEL of 20 ppm (corresponding to dose levels of 4.4 and 3.9 mg/kg/day for males and females, respectively) was identified from this study.
Cancer Assessment: C
Oral Cancer Slope Factor: 5.7 x 10-2 (mg/kg/day)-1
Hepatocellular carcinomas and pheochromocytomas in one strain of mice form the basis of the C classification. Carcinogenicity was not shown in rats.
PQL: 0.005 mg/L
U.S. EPA 502.1; gas chromatography
U.S. EPA 503.1; gas chromatography
U.S. EPA 524.2; gas chromatography-mass spectrometry
PQLs and analytical methods may have been updated since this guidance value was last revised. Updated analytical methods for drinking water and their associated PQLs may be found at http://www.epa.gov/safewater/methods/methods.html
Other Regulatory Data
Any Health Advisories, Reference Doses (RfDs), cancer assessments or Cancer Potency Factors (CPFs) referenced in this document pertain to the derivation of the current guidance value. Updated information may be obtained from the following sources:
Health Advisories - The U.S. EPA provides guidance for shorter-term exposures for chemicals based on their non-cancer effects. Current health advisories may be more current than those used to derive MCLs and may be found at http://www.epa.gov/waterscience/drinking/standards/dwstandards.pdf
RfDs, cancer assessments and CPFs - For specific information pertaining to derivation of drinking water criteria, consult the Federal Register notice that announces the availability of the most current guidance for that chemical. In addition, information on other current RfDs and CPFs as well as cancer assessments for specific chemicals may be found in the U.S. EPA Integrated Risk Information System (IRIS) at http://www.epa.gov/iris/. Please note that the information in IRIS may differ from that used in the derivation process as published in the Federal Register notice.
Federal Register. November 13, 1985. Part IV. Environmental Protection Agency. 40 CFR Part 141. National Primary Drinking Water Regulations: Synthetic Organic Chemicals, Inorganic Chemicals and Microorganisms; Proposed Rule. (50 FR 46936).
Federal Register. July 25, 1990. Part II. Environmental Protection Agency. 40 CFR Part 141 et al.. National Primary and Secondary Drinking Water Regulations; Synthetic Organic Chemicals and Inorganic Chemicals; Proposed Rule.
Federal Register. July 17, 1992. Part III. Environmental Protection Agency. 40 CFR Parts 141 and 142. National Primary Drinking Water Regulations; Synthetic organic Chemicals and Inorganic Chemicals; Final Rule. (57 FR 31776).
Sanders, V.M., K.L. White, et al. 1985. Humoral and cell-mediated immune status of mice exposed to 1,1,2-trichloroethane. Drug Chem. Toxicol. 8 (5): 357-372.
White, K.L, V.M. Sanders et al. 1985. Toxicology of 1,1,2-trichloroethane in the mouse. Drug Chem Toxicol. 8(5): 333-355.
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