Genetic and molecular aspects of 2,3,7,8-tetrachlorodibenzo-p-dioxin action.

Some halogenated aromatic hydrocarbons· (HAHs) such as the polychlori­ nated biphenyls have been used extensively for commercial purposes. Related compounds, such as the halogenated dibenzo-p-dioxins and dibenzofurans, have no commercial value themselves but are generated during the man­ ufacture or combustion of other HAHs. In general, HAHs are lipophilic and stable; halogenation renders them relatively resistant to enzymatic conversion to water-soluble derivatives. Therefore, HAHs tend to persist in the environ­ ment and to accumulate in the food chain, posing a potential risk to human health (l, 2). Toxicologic evaluations reveal that the various HAHs evoke similar responses, although they differ by orders of magnitude in potency; therefore, they are believed to share a common mechanism of action.