MECHANISM OF THE REDUCTION OF FENITROTHION TOXICITY IN KURUMA PRAWN BY PIPERONYL BUTOXIDE

A study on the relation between the toxicity of fenitrothion (FS) and its metabolism in kuruma prawn Penaeus japonicus treated with piperony l butoxide (PB) was performed to elucidate the cause of the remarkable reduction of FS toxicity in the prawn by PB treatment, using C-14 lab eled FS. The PB treatment did not affect FS absorption by the prawn fr om media, but it considerably inhibited the biotransformation of FS to fenitrooxon (FO), i.e. the reduction of FS toxicity in the prawn by P B treatment was attributed to the decrease in FO formation. The minimu m lethal concentration of FO in the prawn was presumed to be 10-14 pmo l/g, whereas that of FS was higher than 400 pmol/g. According to the a mounts of FS and its metabolites found in kuruma prawn treated with an d without PB, the main metabolic pathway of FS in the prawn was presum ed to be esmethylfenitrooxon-->3-methyl-4-nitrophenol-->its conjugates .