Update: August 1993
Current Massachusetts Regulatory Limit
MMCL = 0.005 mg/L. ORS has adopted the MCL issued by the U.S. EPA as part of the Phase II rule. (56 FR 3526; 1-30-91).
Federal Regulatory Limit
The MCL of 0.005 mg/L is based on the PQL for 1,2-dichloropropane. The MCLG is set to zero based on the evidence for carcinogenic potential.
Basis for Criteria
An MCLG of zero is assigned for 1,2-dichloropropane based on carcinogenic effects. The MCL is based on the 1,2-dichloropropane PQL.
Liver toxicity (centrilobular necrosis, liver congestion and hepatic fatty changes reported in animals); kidney effects; lung effects; liver cancer (statistically significant increased incidence of hepatocelleular neoplasms and primary adenomas in male and female B6C3F1 mice); and mammary tumors (dose-related trend in mammary adenocarcinoma in female F344 rats, considered significant since these tumors have a low background rate).
Cancer Assessment B2
The U.S. EPA has revised the cancer classification for 1,2-dichloropropane from a group C to a group B2 based on the results of a 1986 NTP report. The report cited increases in liver carcinomas and also a dose-related trend in mammary carcinomas in female rats. Other considerations include: positive mutagenic activity in short-term assays, and the metabolism of the compound to suspected carcinogenic compounds.
The MCL of 0.005 mg/L is associated with a maximum individual excess lifetime cancer risk* of 1 x 10-5 (56 FR 3526).
PQL: 0.005 mg/L
U.S. EPA Methods 503.1 P/T
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. May 22, 1989. Part II. Environmental Protection Agency. 40 CFR Parts 141, 142 and 143. National Primary and Secondary Drinking Water Regulations; Proposed Rule.
Federal Register. January 30, 1991. Part II. Environmental Protection Agency. 40 CFR Parts 141, 142, and 143. National Primary Drinking Water Regulations; Final Rule. (56 FR 3526).