Reduction of thyroxine levels in the circulation and in the brain of hexachlorobenzene-exposed rats

From studies described in literature, it has become clear that many industrial aromatic halogenated hydrocarbons (AHHs) may pose a threat to the health of humans, particularly of those in the occupational environment. These compounds have found a broad environmental distribution and are contaminating food at low levels. The AHHs share the property of a high fat and low water solubility, a high persistancy to biodegradation and a low turnover rate. Hence, they are deposited in the body in adipose (fatty) tissue, and accumulate in the food chain (plants, fish, mammalian species). The group of AHHs (Table 1), consist of the halogenated benzenes, halogenated biphenyls, halogenated dibenzo-p-dioxins and halogenated dibenzofurans (Fig. 1).