[Effects of DDT and lindane on thyroid function in the rat]

Using the previously described test method, the authors studied with the aid of iodine-131 labelled NaI the effects of daily doses of 30 and 75 mg DDT/kg of body weight, and of 12 and 36 mg of lindane/kg of body weight on the iodine and hormone metabolism in the rat. With DDT, the authors observed a marked increase of the thyroid mass and of the thyroid tri-iodothyronine and thyroxin levels and a simultaneous decrease of the thyroid iodine level. The values for serum iodine and protein-bound iodine were reduced. Serum thyroxin was slightly increased. Serum tri-iodothyronine was markedly increased, which was also true of the iodine fractions in the liver. Lindane was considerably less effective. Only the decrease of thyroid tri-iodothyronine and the simultaneous increase of thyroid thyroxin were striking. In the serum, both hormones remained unchanged. The values for the urine fractions of both the active principles were indicative of a hypofunction. The causes of the changes observed were discussed with regard to the findings of other authors. The present results permit the conclusion that the effects of the pesticides tested are obviously complex by nature.