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 administ ered 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 inhib ited at these two doses. At 0.5, 1.5 and 2 mg/kg/day, however, quinalphos d id not produce any such changes. Up to a dose of 2 mg/kg/day there was no f oetotoxic or teratogenic effect, as evidenced by number of implantation sit es, 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 r ats. (C) 1999 Elsevier Science Lid. All rights reserved.