The metabolism ofO-(4-bromo-2, 5-dichlorophenyl)O-methyl phenylphosphonothioate (leptophos) in white mice and on cotton plants

Abstract

The metabolism of¹⁴C-labeled leptophos (O-methylO-4-bromo-2, 5-dichlorophenyl phenylphosphonothioate), a new phosphonothioate insecticide chemical, was examined in the white mouse and the cotton plant. Leptophos, administered orally to the mouse, is rapidly metabolized and excreted as degradation products, principally in the urine. The major degradation products are 4-bromo-2, 5-dichlorophenol (in the form of conjugates),O-methyl phenylphosphonothioic acid, methyl phenylphosphonic acid, and phenylphosphonic acid. Small amounts of unchanged leptophos and leptophos oxon occur in the mouse feces. In general, the same alteration products are also obtained when leptophos is applied to the leaf surface of cotton plants. However, leptophos is quite stable on the cotton plant and the major portion of the radioactive material recovered from the plant is unchanged leptophos. The results indicate that leptophos is useful as a long-term residual insecticide without the problem of biomagnification in the food chain.