The effect of a single dose of DDT on thyroid function in male rats.

A single dose of 100 mg/kg of commercially available 1, 1, 1,-trichloro-2, 2, bis (p-chlorophenyl), ethane, (DDT), dissolved in corn oil, was administrated to adult male Sprague-Dawley rats by stomach tube and two indices of thyroid function were examined. The iodide transport function of the thyroid gland determined by the thyroid: serum radioiodide concentration ration, (T:S) was depressed, and complete inhibition in thyroidal radioiodine release occurred 8 to 10 hr following administration of DDT and continued for 24 to 30 hr. Subsequently the block in thyroidal 131I release was followed by a return to a rate not significantly different from that of control rats. Whether the acute effects of a single large dose of DDT on thyroid function are a consequence of a local action on the thyroid gland or on pituitary thyrotropin release, or of some action elsewhere is not clear.