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Benzene Structural Formula
Benzene Structural Formula
CAS Number: 71-43-2
Synonyms: Benzol, Coal naphtha, Phene, Polystream, Pyrobenzol
Contaminant Type: Chemical

Benzene is a colorless, highly flammable, volatile organic chemical. It is used extensively as a solvent in the chemical and drug industries, as a starting material and intermediate in the production of numerous chemicals, including plastics, rubber, elastomers, phenol, acetone, and nylon, and as a gasoline additive. [687] Benzene’s trade names and synonyms are Polystream, benzol, pyrobenzol, coal naphtha, and phene. [686] More than 98% of the over 3 billion gallons of benzene produced in the United States annually is derived from the petrochemical and petroleum refining industries. [687]

Benzene is introduced to the environment primarily through industrial processes. Air emissions from burning coal and oil, motor vehicle exhaust, evaporation from gasoline service stations, and benzene storage and waste operations lead to increased levels of benzene in the atmosphere. Benzene is released into water and soil from sources such as industrial discharge, spills, gasoline leaks from underground storage tanks, and disposal of benzene and products containing benzene. [687]

Benzene's high volatility is the controlling physical property in the environmental transport of the chemical. Degradation reactions with other chemicals in the atmosphere (primarily hydroxyl radicals) limit the atmospheric residence time of benzene to only a few days. [687] Benzene is moderately soluble in water, and partitions readily to the atmosphere from surface water. The soil organic carbon sorption coefficient (Koc) for benzene has been measured with a range of 60-83, indicating that benzene is highly mobile in soil and readily leaches into groundwater. [687] In water and soil, benzene is subject to volatilization, photooxidation, and biodegradation. There is no evidence of the biomagnification of benzene in the aquatic food chain. [687]

Benzene is designated as a hazardous substance by USEPA in accordance with the Clean Water Act. In drinking water, the maximum contaminant level (MCL) set by USEPA is 5 ppb, while a maximum contaminant level goal (MCLG) is set at 0 ppb. [686, 687] USEPA has identified packed tower aeration and granular activated carbon as best available technologies capable of removing volatile organic compounds from water to their respective MCLs. [704] USEPA has determined that benzene is a known human carcinogen, classifying it as a Group A chemical. [687] Long-term exposure to benzene has been found to cause cancer, specifically leukemia, which is cancer of the blood-forming organs. Exposure is also likely to be harmful to the reproductive organs, immune system, formation of bone marrow, and can lead to anemia. [687]

Date of Literature Search: July 2009

686 USEPA; 2009; Consumer Factsheet on: Benzene; http://www.epa.gov/OGWDW/contaminants/dw_contamfs/benzene.html; As posten on July 7, 2009. USEPA Office of Ground Water and Drinking Water, Washington, DC.
687 Wilbur, S., Keith, S., Faroon, O., Wohlers, D., Stickney, J., Paikoff, S., Diamond, G. and Quinones-Rivera, A.; 2007; Toxicological Profile for Benzene; Toxicological Profile for Benzene; U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry. pp. 2-9, 243-310.
704 Dyksen, J., Cline, G., Blanck, C., Budd, G., DeMarco, J., Hess, A., Lykins, B., Marino, D., O'Brien, R., Raczko, R., Rogers, P., Schorr, P., Snyder, E., Sorg, T. and Brittan, J.; 1991; Existing VOC Treatment Installations: Design, Operation, and Cost; Existing VOC Treatment Installations: Design, Operation, and Cost; Committee Report. Table A-1. American Water Works Association, Water Quality Division, Organic Contaminants Control Committee, Denver, CO.