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CASRN: 71432

Update: August 1993

Current Massachusetts Regulatory Limit
MMCL = 0.005 mg/L. ORS has adopted the MCL published by U.S. EPA in the Phase I rule. (52 FR 25690; 7/8/87) 

Federal Regulatory Limit
 The MCL for benzene is based on its detection limit of 0.005 mg/L. The MCLG is equal to zero.

Basis for Criteria
An MCLG of zero is assigned for benzene based on the evidence for carcinogenic potential. The MCL is based on the benzene PQL.

Critical Effects
In humans, exposure to benzene is associated with myelocytic anemia, thrombocytopenia and leukemia. In animals, an increase in tumors and leukemia have been reported. 

Cancer Assessment
Benzene is currently classified as a group A, human carcinogen. Slope factor = 2.9 x 10-2 (mg/kg/day)-1 from the one-hit model. 


Analytical Information
: The PQL used as the basis for the MCL is 0.005 mg/l

Analytical Methods

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

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

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 Please note that the information in IRIS may differ from that used in the derivation process as published in the Federal Register notice.

Aksoy, M., S. Erdem and E.G. Dincol. 1974. Leukemia in shoeworkers exposed to benzene. Mood. 44(6): 837-841.

Federal Register. July 8, 1987. Part II. Environmental Protection Agency. 40 CFR Parts 141 and 142. National Primary Drinking Water Regulations-Synthetic Organic Chemicals; Monitoring for Unregulated Contaminants; Final Rule. (52 FR 25690). IARC (International Agency for Research on Cancer). 1982. Benzene. In: Some industrial chemicals and dye stuffs.

IARC Monographs on the evaluation of carcinogenic risk of chemicals to humans. IARC. WHO. Lyn Frand. 29:93-148.