POLYCHLORINATED BIPHENYLS (PCBs) 
Update: March 1996
Current Massachusetts Regulatory Limit
MMCL = 0.0005 mg/L. ORS has adopted the MCL published by the U.S. EPA (56 FR 3256: 1/30/91).
Federal Regulatory Limit
Final. The MCL for polychlorinated biphenyls (PCBs) is set at the PQL of 0.0005 mg/L. The MCLG is set at zero based on carcinogenic effects.
Basis for Criteria
An MCLG of zero is assigned for PCBs based on the evidence for carcinogenic potential. The MCL is based on the PCB PQL.
The U.S. EPA currently classifies PCBs as a group B2 carcinogen. There are 209 PCB isomers but they are regulated as a group. As a group B2 carcinogen, the MCLG for PCBs is set at zero. The MCL for group B2 carcinogens is set at a level as close to zero or at an extra risk level of 1 x 10-6 as is feasible. The MCL is based on the PQL for PCBs.
Cancer Assessment: B2
Rats and mice fed PCBs (Aroclor 1260) in their diets for two years developed neoplastic nodules and hepatocellular carcinomas. Based on positive results in rats and mice, U.S. EPA has classified PCBs as Group B2 carcinogen (i.e., sufficient animal evidence and inadequate human evidence).
The MCL of 0.0005 mg/L is associated with an individual excess lifetime cancer risk of one in ten thousand (1 x 10-4).
Synthetic Organic Chemicals
PQL: 0.0005 mg/L
U.S. EPA 505 microextraction/GC
U.S. EPA 508 electron capture/GC
U.S. EPA 508A perchlorination/GC
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. 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).
 The MCL for PCBs applies to the decachlorobiphenyl species.