Toxicity of endosulfan: distribution of alpha- and beta-isomers of racemic endosulfan following oral administration in rats.

Endosulfan was administered orally (2.5 and 7.5 mg/kg) daily to male rats for a period of 60 days. The distribution pattern of alpha and beta-isomers was studied using a gas-liquid chromatograph equipped with an electron capture detector. There was a significant increase in liver and lung weights. The testes weight was slightly decreased. No significant change in weights of other tissues was observed. At both dose levels, the concentration of alpha-isomer was highest in kidney (574 and 1655 ng/g, respectively), followed by lung, ventral prostate, spleen, testes and brain. In the seminal vesicle, epididymis, heart and liver, the concentration of beta-isomer was higher than the alpha-isomer. The results of the study indicated a differential ability to accumulate the two isomers of endosulfan which may help to explain the difference in the toxic potential of the alpha- and beta-isomers.