Intrauterine exposure to parathion increases its disposition rate in postnatal life

The effect of in utero exposure to parathion was assessed in offspring from dams treated with low doses of parathion during gestation. An analytical method to measure parathion in small blood samples (200 microliters) was used which prevented significant bleeding during sampling. Pharmacokinetic studies were performed in anesthetized 6-week-old male rats and showed a monoexponential pattern of elimination. The offspring exposed in utero to parathion depicted a higher plasma disposition rate of the insecticide than the control group (T1/2 el 60 +/- 18.2 and 24.8 +/- 13.1 min, respectively; p less than 0.05), suggesting the presence of some adaptive mechanism. This mechanism might render the in utero exposed animal less liable to the toxic effects of this pesticide during the postnatal life. The increase observed in the elimination rate does not seem to be due to higher secretory activity of the kidney, and metabolic mechanisms might be involved.