Excretion and tissue distribution of 2,3,7,8-tetrachlorodibenzo-p-dioxin in the rat.

The compound, 2,3,7,8-tetrachlorodibenzop-dioxin (TCDD), is highly toxic. The LD50 for male and female rats given a single oral dose is 23 and 45 jug/kg, respectively (1). Adverse effects have been observed in a teratology study in which pregnant rats were given oral doses of 0.125-2.0 jug/kg-day TCDD from day 6 through day 15 of gestation (2). The adverse effects were increased fetal mortality, early and late resorptions and intestinal hemorrhage in the fetuses. No adverse effects were noted at the 0.03 ptg/kgday level. In humans and rabbits, contamination of the skin with TCDD produces chloracnelike lesions (3, 4). This disease is characterized by the appearance of hyperkeratosis, papules, comedones and cysts. There is no available information on the absorption, excretion or tissue distribution of TCDD in animals. Therefore, this study was done to determine the excretion and tissue distribution of radioactivity derived from TCDD-14C following a single oral dose of the labeled compound.