Neurotoxicity of Halogenated O-Phenyl O-Alkyl Alkylphosphonothioates

Twenty-seven halogenated organophosphorus esters were tested for neurotoxicity in adult hens. Fourteen compounds were overtly neurotoxic, including eight OF eleven methylphosphonothioates, three of seven ethylphosphonothioates, and three of six phosphorami-dates, one of which was the commercial herbicide DMPA. Neurotoxic activity varied both with the number of halogen substituents on the phenyl group, and with the identity of the 4-phenyl halogen, Neurotoxic activity also varied with the alkyl group involved in the P-C or P-N bond, and with the identity of the 0-alkyl group.