Update: August 1993
Current Massachusetts Regulatory Limit
MMCL = 0.001 mg/L. ORS has adopted the MCL published by the U.S. EPA as part of the Phase V rule (57 FR 31776: 7-17-92).
Federal Regulatory Limit
The MCL for hexachlorobenzene is based on its detection limit of 0.001 mg/L. The MCLG is equal to zero.
Basis for Criteria
The MCL of 0.001 mg/L is set at the PQL for hexachlorobenzene of 0.001 mg/L. The MCLG is set to zero based on the evidence for carcinogenic potential.
Acute exposure to hexachlorobenzene for relatively short periods of time at levels above the MCL could result in skin lesions and nerve and liver damage. Chronic lifetime exposure to concentrations above the MCL may produce damage to the liver and kidneys, reproductive effects, benign tumors of the endocrine glands and cancer.
Hepatocellular carcinomas were produced in Sprague-Dawley female rats exposed to hexachlorobenzene in the diet.
U.S. EPA has classified hexachlorobenzene as a B2 probable human carcinogen. The MCL of 0.001 mg/L is associated with a maximum individual risk* of 5 x 10-5 (57 FR 31776).
* This information on risk is extrapolated from information provided in the July 17, 1992 Federal Register that a 1 x 10-4 Excess Lifetime Cancer Risk (ELCR) is associated with a concentration of 0.002 mg/L.
PQL: 0.001 mg/L
U.S. EPA Methods 505; 508; 508.1; 525.2.
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 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. (55 FR 30370)
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).