Evaluation of pesticide effects on parameters of male reproduction in the mouse

The purpose of this study was to determine the effects of the insecticides Kepone and carbaryl (Sevin^R) and the nematocide 1,2-dibromo, 3-chloropropane (DBCP) on parameters of male reproduction in the mouse. Mice were given 10 mg/kg kepone every 3 days for up to 44 days, 150 mg/kg carbaryl every 2 days for up to 68 days, or 10 mg/kg DBCP every 3 days for up to 44 days. Pesticides were dissolved in corn oil and administered by gavage. Controls received a dose of corn oil alone to match the volume used as a solvent.

The effects of these three pesticides were evaluated relative to testicular weight, percent of abnormal sperm, epididymal sperm counts and testicular histology. Body and liver weights, plasma acetylcholinesterase levels in carbaryl-treated mice and tissue levels of pesticide in kepone and DBCP-treated mice were measured in order to document absorption of the pesticides. The major findings were as follows: (1) Kepone caused an increase in percent of abnormal sperm by day 36 of treatment and a rise in liver weight by day 16 of treatment. After suspension of treatment on day 44, percent of abnormal sperm returned to normal but liver weight did not. (2) Carbaryl had no effects on any of the parameters of male reproduction studied in this research. (3) DBCP caused a decrease in testis weight by day 44 of treatment and a lowering of epididymal sperm counts by day 36, with an elevation of liver weights. (4) Corn oil, which contains estrogen-like compounds, induced densely staining vacuolated bodies in the seminiferous tubules of the testis. These dense bodies were observed to occur in all three pesticide treatments as well as in corn oil treated controls but were not observed in mice which did not receive corn oil, suggesting that the corn oil was responsible for the presence of these dense bodies. The occurrence of dense bodies was not significantly different in pesticide-treated mice compared to corn oil treated controls. The data presented here suggest that absorption of kepone and DBCP may lead to adverse effects on male reproduction but do not demonstrate such effects from carbaryl.