Assessment of the No-observed-effect Level (NOEL) of Quinalphos in Pregnant Rats

Technical quinalphos (0.5, 1.5, 2, 3 or 4.5 mg/kg body weight) was administered orally to pregnant rats from day 6–15 of gestation. At 3 and 4.5 mg/kg/day, quinalphos produced significant changes in hepatic ALT, ALP and serum ALT, AST, ALP and LDH activity along with hepatocellular changes in dams. The AchE activity in brain and red blood cells was also significantly inhibited at these two doses. At 0.5, 1.5 and 2 mg/kg/day, however, quinalphos did not produce any such changes. Up to a dose of 2 mg/kg/day there was no foetotoxic or teratogenic effect, as evidenced by number of implantation sites, percent resorption, foetal weight, morphological, visceral and skeletal evaluations. Hence, 2 mg/kg body weight of quinalphos could be considered as the no-observed-effect level (NOEL) on foetal and maternal toxicity in rats.