Update: March 1989
Current Massachusetts Regulatory Limit
MMCL = 0.007 mg/L. ORS has adopted the MCL published by U.S. EPA.
Federal Regulatory Limit
The MCLG for 1,1-dichloroethylene is zero based on the evidence for carcinogenic potential. This value was promulgated as part of the National Primary Drinking Water Regulations: Synthetic Organic Chemicals; Monitoring for Unregulated Contaminants; Final Rule on July 8, 1987 (52 FR 25690).
Basis for Criteria
An MCLG of zero is assigned for 1,1-dichloroethylene based on carcinogenic effects. The MCL is based on the 1,1-dichloroethylene PQL.
Acute exposure to 1,1-dichloroethylene for relatively short periods of time at levels above the MCL may cause liver toxicity. Chronic exposure to 1,1-dichloroethylene may cause liver and kidney damage, fetal toxicity and cancer. A 2-year chronic study in which rats were exposed to 0, 50, 100 and 200 ppm of 1,1-dichloroethylene produced mid-zonal fatty accumulation in liver although no liver degeneration. A LOAEL of 100 mg/kg/day was identified from this study (Fed. Reg., 1985).
U.S. EPA has classified 1,1-dichloroethylene as a C (possible) human carcinogen under the 1986 Carcinogen Risk Assessment Guidelines.
PQL: 0.007 mg/L
U.S. EPA Methods 502.2; 524.2
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. July 8, 1987. Part II. Environmental Protection Agency. 40 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 8, 1987. National Primary Drinking Water Regulations - Synthetic Organic Chemicals; Monitoring for Unregulated Contaminants; Final Rule. (52 FR 25690).