Health Assessment Document for Chlorinated Benzenes. Final Report
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The chlorinated benzenes are a group of 12 compounds (monochlorobenzene; 1,2-, 1,3-, 1,4-dichlorobenzene; 1,2,3-, 1,2,4-, 1,3,5-trichlorobenzene; 1,2,3,4-, 1,2,3,5-, 1,2,4,5-tetrachlorobenzene; pentachlorobenzene; and hexachlorobenzene). Environmental contamination results from emissions to air and water during the manufacture and use of the chlorinated benzenes and from the disposal of wastes from a number of processes. These compounds are resistant to chemical and biological degradation and tend to accumulate in lipid-containing tissues of animals and humans. The ubiquitous environmental distribution of the chlorinated benzenes and their bioconcentration in humans are a basis for concern over the consequences of chronic exposure to human health. The first portion of the health assessment document is devoted to the chlorinated benzenes in the environment: physical and chemical properties, the monitoring of the chlorinated benzenes in various media, natural and human-made sources, the transport and distribution of the chlorinated benzenes within environmental media, and the levels of exposure. The second part is devoted to biological responses in laboratory animals and humans including metabolism, pharmacokinetics, as well as the toxicological effects of the chlorinated benzenes. This document forms the scientific basis for a proposed decision by EPA concerning the regulation of the Chlorinated Benzenes under the Clean Air Act.