Toxicology of chlorinated dibenzo-p-dioxins.

Severe toxicological responses have been associated with certain chlorodibenzodioxins. One of these responses is chloracne, a folliculosis first associated with skin contamination by chlorohydrocarbons in 1899 (1)). Serious outbreaks of chloracne-like lesions associated with runaway reactions in the production of 2,4,5-trichlorophenol occurred in Germany in the early 1950's (2). 2,4,5Trichlorophenol itself does not cause acne (3), but the contaminants which may be formed in the uncontrolled production of 2,4,5-trichlorophenol are extremely potent acnegens (2). 2,3,7,8-Tetrachlorodibenzo-pdioxin and triand tetrachlorodibenzofuran were isolated from the contaminants formed in 2,4,5-trichlorophenol production and were demonstrated to be strongly positive acnegens when applied to rabbit ears (3). By using the rabbit ear test, the acnegenic potency of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) was confirmed in 1962 (4). In addition, 2,3,7,8-TCDD is extremely toxic in the chick embryo assay (5) and is highly embryotoxic in rats (6). Another chlorodibenzodioxin, hexachlorodibenzo-pdioxin (HCDD), is known to be positive for the chick edema factor, a condition characterized by hydropericardium, ascites, and anasarca (5, 7).