Benzene carcinogenic classification

The number of clear human epidemiologic studies is small. A total of approximately 50 compounds (c.g., benzene, vinyl chloride) and complex e.xposures (e.g., aluminum production, tobacco smoke) have sufficient data available to permit their classification as human carcinogens. The most potent human carcinogens known, the aflatoxins. are of natural origin. Their presence in food products through infestation by toxin-producing fungi constitute a serious problem in several tropical and subtropical countries. 

One TPH compound (benzene) has been shown to cause cancer (leukemia) in people. The International Agency for Research on Cancer (IARC) has determined that benzene is carcinogenic to humans (Group 1 classification). Some other TPH compounds or petroleum products, such as benzo(a)pyrene and gasoline, are considered to be probably and possibly carcinogenic to humans (IARC Groups 2A and 2B, respectively) based on cancer studies in people and animals. Most of the other TPH compounds and products are considered not classifiable (Group 3) by IARC. See Chapter 6 for more information on how TPH can affect your body. 

In this classification benzene is included in the first group, which is that of the highly hazardous compounds. Consequently in most countries the use of benzene is restricted to those processes where it is essential as a reactant or originates from natural products, such as petroleum derivatives and gasoline. Other aromatic compounds, such as toluene and xylene, also present a relatively high toxicity, but not as much as that of benzene and they do not exhibit strong carcinogenic properties. 

Occnpational Safety and Health Administration, Identification, Classification and Regnlation of Potential Occupational Carcinogens, 45 Fed. Reg. 5001 (1980) American Petroleum Institute v. Industrial Union, AFL-CIO, 448 U.S. 607 (1980) Thomas O. McGarity, The Story of the Benzene Case Judicially Imposed Regulatory Reform through Risk Assessment, in Environmental Law Stories 141 (Richard Lazarus Oliver Houck, eds. 2005). 

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