Insecticide residues and cholinesterase inhibition in zebra finches orally dosed with fenitrothion

Fenitrothion residues and cholinesterase (ChE) activities were measured in zebra finches given acute, oral doses of fenitrothion insecticide. Dosage rates were 1.04, 3.80, and 11.36 mg/kg. Residues declined rapidly but were still detectable at trace levels (<0.005 mg/kg) 96 h after treatment. Peak brain and plasma ChE inhibitions averaged between 50–76% and 79–89%, respectively. Plasma ChE recovered more rapidly (1–4 days) than brain ChE (10 days or more). Brain and plasma ChE inhibitions were positively, but weakly, correlated with fenitrothion body burden.