Mirex kinetics in the rhesus monkey. I. Disposition and excretion.

Three female rhesus monkeys were given 14C-Mirex (5.23 mCi/mmol) iv (two animals) or po (one animal) in a dose of about 1 mg/kg for the purpose of determining the distribution and excretion of this polycyclic perchlorinated insecticide. Blood, plasma, urine, feces, and tissue samples were analyzed for 14C content. Monkeys were autopsied 23, 106, and 388 days after receiving 14C-Mirex. Following iv administration, plasma 14C showed a rapid decrease over the first few hours from the initial high levels. In the monkey given the compound orally, 14C first appeared in the plasma at 2 hr and reached a maximum at 5 hr. Thereafter, the decline in plasma radioactivity paralleled that found in the animals dosed i.v. After 2 weeks, the rate of decline in all animals was very slow. Excretion and tissue distribution of Mirex were essentially the same whether the compound was given po or iv. Less than 0.6% of the dose was found in the urine. 14C was excreted in the feces for the duration of the experiment with a maximum cumulative excretion of 7% after 388 days. At autopsy all tissues analyzed contained 14C. The highest concentration of 14C was found in the fat (estimated to contain at least 80% of the dose), followed by adrenal, peripheral nerve, thyroid, and skin. Chemical analysis of the nature of the radioactivity in fat and feces showed that at least 95% and was present as unchanged Mirex. There was a small amount of a compound more polar than Mirex in the feces, containing less than 3% of the fecal radioactivity.