The effect of
zinc ethylenebisdithiocarbamate (
zineb) and
manganese ethylenebisdithiocarbamate (
maneb) has been studied in a chronic experiment (4.5 months) on albino rat thyroid gland and gonads. A complex of biochemical, morphological (histological, histochemical and electronmicroscopic), radiological, functional and
biological methods has been employed. Different groups of rats were subjected to inhalatory
poisoning with
zineb in concentrations 110, 50, 10 and 2 mg.m-3 and
maneb in concentrations 135, 12 and 2 mg.m-3. It was established that both compounds provoke toxic irritative changes in the lung and the trachea, more strongly expressed with
maneb. A correlation of the dose and the effect was determined. At a
zineb dose 0.1 LD50 and 0.01 LD50 applied twice weekly an increased 131l uptake (rebound phenomenon) was found and signs of increased activity of the thyroid gland. At doses 0.1, 0.02 and 0.01 LD50 both for
zineb and
maneb and an additional dose 0.002 LD50 for
maneb, a decrease in the fertile capacity resulting from the damage of the germinative was determined (atrophic changes in Sertoli cells, deserted tubuli seminiferi because of disturbed maturation of the spermatozoa; small number or lack of differentiated forms of spermatogenesis; suppressed ovopoiesis, increased number of atretic follicles, with the domination of the relative part of the growing follicles) and endocrinoactive structures (destruction to disappearing of Leydig's cells; injured cells of Theca interna, granulosa and interstitium). These data as well as the data for teratogenicity give us grounds to recommend a higher security coefficient in hygiene standardization.