CHLORPYRIFOS - HAZARD ASSESSMENT BASED ON A REVIEW OF THE EFFECTS OF SHORT-TERM AND LONG-TERM EXPOSURE IN ANIMALS AND HUMANS

Analyses of potential dietary exposure to chlorpyrifos residues were c onducted by the Department of Pesticide Regulation (DPR). Potential ac ute dietary ingestion of chlorpyrifos for all labelled uses was based on the 95th percentile of user-day exposures. Margins of safety (MOSs) for potential acute dietary exposure to chlorpyrifos residues were ba sed on a no-observed-effect level (NOEL) for cholinergic signs in a hu man study, and ranged from 52 to 205 for all population subgroups. MOS s for potential chronic dietary exposure to chlorpyrifos residues were based on a NOEL for inhibition of brain cholinesterase activity in ra ts and dogs, and ranged from 2198 to 8065 for all population subgroups . The limitations on toxicity, consumption and residue data are discus sed, with the assumptions necessitated by those limitations.