METABOLISM OF DIFLUBENZURON BY SOIL-MICROORGANISMS AND MUTAGENICITY OF THE METABOLITES

Diflubenzuron [1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea], a new urea-based insecticide, was found to be rapidly degraded by four eucaryotic microorganisms: Fusarium sp. Cephalosporium sp. Penicillium sp., and Rhodotorula sp. Cleavage of the urea bridge yielded 2,6-difluorobenzoic acid, 4-chlorophenylurea, 4-chloroaniline, 4-chloroacetanilide, acetanilide, and 4-chlorophenol. Analysis of the diflubenzuron metabolites, using the Salmonella mutagenicity test, revealed that 2,6-difluorobenzoic acid gave a false positive at high concentrations because of its lethal effect on the test bacterium. The metabolites 4-chloroaniline, 4-chlorophenol, and 4-chlorophenylurea were borderline mutagens. © 1979.