Document omJ8oejex43dMK5x9Lz0ODMVR

27 PCDDs are in progress. The carcinogenic potentials of PCDFs have not been studied. 2,3,7,8-TCDD is teratogenic in mice and hamsters. The threshold teratogenic dose in mice was estimated to be 0.1 meg per day (Smith et al, 1976). 2,3,7,8-TCDD has been shown to be etotoxic in a wide variety of species, including primates. HCDD was teratogenic in rats at a dose of 100 meg/kg per day (IARC* 1977) There is as yet no data on the fetotoxic potentials of PCDFs in animals. The toxic effects of 2,3,7,8-TCDD in man are summarized in Table7. The toxic effects most consistently observed in occupational studies are chloracne liver dysfunction, neuropsychiatric disturbances, and abnormalities in porphyrin metabolism. Table 8 summarizes the findings of the morbidity studies of workers exposed to 2,3,7,8-TCDD to date. The few follow-up studies which have been done show resolution of gross liver dysfunction and porphyrin abnormalities following removal from exposure. (Pazderova-Vijlupkova et al, 1981; Suskind, 1984). Several of the occupational exposures occurred as the result of uncontrolled exothermic reactions during the production of trichlorophenol. A similar process accident at Seveso, Italy in 1976 resulted in widespread community exposure to 2,3,7,8-TCDD. Health effects included chloracne, primarily in children, and peripheral neuropathy in a small percent of those exposed (Pocchiari et al, 1979). The epidemiologic studies on the carcinoger.ecicv of TCDD are summarized in Table 9- While individual occupational mortality studies reveal no excess of cancer, the pooled data suggest an excess of soft tissue sarcoma (Honchar and Halperin, 1981).