Aldicarb sulfoxide/aldicarb sulfone mixture in drinking water of rats: effects on growth and acetylcholinesterase activity.

A 1:1 mixture of aldicarb sulfoxide/aldicarb sulfone was administered to young adult Wistar rats via the drinking water at nominal concentrations of 19.2, 4.8, 1.2., 0.3, 0.075, or 0 ppm for 29 d. Blood was collected after 8, 15, and 29 d of treatment for plasma and erythrocyte cholinesterase determinations, and brain cholinesterase was determined at sacrifice. Body weight, food intake, and water consumption were measured weekly. Body weight gain and water consumption were reduced at 7, 14, 21, and 29 d in male and female rats at 19.2 ppm. Food consumption was reduced in males at 7, 14, 21, and 29 d but was reduced in females only on d 7. Both plasma and erythrocyte cholinesterase activity were reduced after 8, 15, and 29 d in male and female rats at 19.2 ppm. Males at 4.8 ppm showed reductions in plasma activity only after d 8 and in erythrocyte activity only after d 29. Female rats at 19.2 ppm also displayed depressions in brain cholinesterase activity not observed in similarly treated males. Since the only effects noted at 4.8 ppm were reductions in plasma and red blood cell cholinesterase activity in males only and at only one of three sampling periods, these two instances are not believed to be of any biological significance. The data suggest that 4.8 ppm in drinking water is a no observable ill-effect level for exposure of rats to aldicarb residues based on the parameters measured in this study.