EFFECTS OF THE SUBCHRONIC ADMINISTRATION OF ZINC ETHYLENE-BIS-DITHIOCARBAMATE (ZINEB) TO RABBITS

The effects of subchronic administration (90 d) of zineb were studied in male New Zealand. Rabbits were allotted to 3 groups of 8 animals ea ch and offered diets containing 0, 0.3 or 0.6% zineb. A marked decline in weight gain, hemoglobin concentration, hematocrit, and erythrocyte and leucocyte counts occurred at the highest zineb dosage. There was a dose-related depression in circulating thyroid hormones, whereas ser um lipid concentration, particularly that of cholesterol and triglycer ides, increased. Hepatic lipid concentration was considerably reduced in rabbits exposed to 0.6% zineb. Neither serum testosterone nor the a ctivities of selected testicular enzymes showed changes suggestive of testicular involvement. Pathological changes were in agreement with bi ochemical findings; there was a marked dose-related enlargement of the thyroid showing histological colloid struma. An increase in relative weight and moderate glycogenosis were detected in liver, whereas no le sions occurred in testes. It was concluded that thyroid and liver are the main targets for zineb toxicity in the rabbit. Unlike the results from previous studies conducted on other food-producing species, repea ted exposure of rabbits to zineb failed to cause testicular damage. Th is might be related to the inability of zineb to significantly accumul ate in the testes.