Transplacental disposition and teratogenic effects of chlorpyrifos in rats.

Rats were orally fed with different doses viz. 9.6, 12 and 15 mg/kg/d from GD 0-20 and examined for evidence of fetotoxicity and teratogenecity to evaluate the potential effects of technical chlorpyrifos (97%). Fetotoxic effects were not observed at tested dose levels as evidenced by number of implantations, number of corpora lutea and live fetuses/dam, but significant alterations were noted in percent delta resorption and fetal weight. There were no major malformations, but some minor anomalies such as reduced parietal ossification and absence of phalanges found significant in high dose were not considered as compound-related effects. On the other hand the accumulation of chlorpyrifos residue in dams was more in brain (0.0328 micro g/g) than in liver (0.0071 micro g/g).The level of residue in fetuses was in the following order : liver (0.0531 micro g/g) > brain (0.0364 micro g/g) >placenta (0.040 micro g/g) > amniotic fluid (0.0010 micro g/g). Although, the total residue was higher in fetuses (0.0447 micro g/g) than in dams (0.0120 micro g/g), the absence of abnormalities in fetal gross morphology, visceral and skeleton suggest that technical chlorpyrifos at tested dose levels is non-teratogenic in rats.