EFFECTS OF THE PESTICIDES CARBOFURAN, CHLORPYRIFOS, DIMETHOATE, LINDANE, TRIALLATE, TRIFLURALIN, 2,4-D, AND PENTACHLOROPHENOL ON THE METABOLIC ENDOCRINE AND REPRODUCTIVE ENDOCRINE SYSTEM IN EWES

Many pesticides are used in the agricultural environment, and some may have the potential to disrupt reproductive or endocrine function. Ewe s, in separate groups of 6, received orally into their rumen either em pty gelatin capsules or capsules containing chlorpyrifos (12.5 mg/kg), trifluralin (17.5 mg/kg), lindane (2.5 mg/kg), or pentachlorophenol ( 2 mg/kg) 2 times per week for 43 d. Dimethoate (0.2 mg/kg), carbofuran (0.30 mg/kg), 2,4-dichlorophenoxyacetic acid (10 mg/kg), or triallate (5 mg/kg) was given 3 times per week. After 36 d of treatment, blood samples were taken every 12 min for 6 h for hormone analysis. Ewes wer e euthanized at the end of the study for necropsy and histopathology. No overt signs of toxicity were seen, and body weight was not affected by treatment. Carbofuran caused a significant increase in serum conce ntrations of thyroxine compared to control ewes, but all other pestici des, except trifluralin, resulted in a marked decrease in thyroxine co ncentrations. Serum concentrations of cortisol were significantly incr eased by trifluralin and chlorpyrifos. Concentrations of insulin in se rum were markedly increased in ewes given dimethoate, lindane, triflur alin, triallate, and pentachlorophenol, and concentrations of estradio l were also significantly increased in ewes given lindane and triflura lin. Mean serum concentrations of LH were markedly decreased by triflu ralin, and basal LH concentrations were significantly decreased by lin dane, dimethoate, and trifluralin but increased by triallate. Both pen tachlorophenol and triallate caused a significant increase in severity of oviductal intraepithelial cysts in ewes. Data suggest that several currently used pesticides could influence serum concentrations of rep roductive and metabolic hormones, particularly thyroxine, the major se cretory product of the thyroid and a principal regulator of metabolism .