Chlorinated hydrocarbon residues in perianal fat of desert bighorn sheep.

Use of chlorinated hydrocarbon pesticides for more than 30 years and polychlorinated biphenyls (PCB) for more than 40 years has resulted in the accumulation of these compounds in various ecosystems. Their accumulation in different ecosystems both near and well removed from their source of application is enhanced principally by their persistence and subsequent magnification between trophic levels. Particularly noted for their residual properties are DDT and dieldrin as they can remain in their original state in the soil or be converted to various breakdown products. Photodecomposition of dieldrin results in products more toxic than the parent compound (SOTO and DIEC~V~N 1967:307).