Neurotoxicity assessment of O‐ethyl‐O'‐(2‐diisopropylaminoethyl) methylphosphonite (QL) in hens

O‐ethyl‐O'‐(2‐diisopropylaminoethyl) methylphosphonite (QL), an intermediate in the formation of ethyl S‐2‐diisopropylaminoethyl methylphosphonothiolate, was evaluated for neurotoxicity in the adult hen. Birds were given a single oral dose of QL ranging from 635 to 6080 mg kg −1 . The QL‐treated hens were observed for up to 24 h after dosing for acute toxicologic effects and over a 24 d post‐dose period for evaluation of delayed neurotoxicity. The oral LD 50 in hens is 1186 mg kg −1 . Neurologic dysfunction, as evidenced by motor incapacitation, was observed at 6 days and thereafter after treatment with QL. Neurotoxic esterase (NTE) activity was not inhibited at 24 h after exposure to compound. Neural damage, multifocal in nature, was noted in the peripheral nervous system of QL‐treated hens at dose levels ≥ 635 mg kg −1 , oral dose. These findings indicate neural damage tendencies following QL exposure.