Studies were made on an analytical method for determining residues of oxadiazon herbicide in fish and shellfish, consumption of which has recently increased, and the levels of residues in crucian carps were investigated. In order to eliminate interference, particularly of PCBs and organochlorine insecticides, which had contaminated freshwater and marine fishes at high levels, conditions of Florisil column chromatography and ECD gas chromatography were examined and one method was found for routine analysis of oxadiazon where a recovery of 96.0% could be obtained. When the flesh of crucian carps, collected in Lake Kojima 2 months, 4 months and 9 months after application of oxadiazon, was analyzed by this method, 0.442ppm, 0.046ppm and 0.017ppm were detected, respectively. This suggests the possibility that oxadiazon may have a strong persistence in fish. Identification was carried out by means of mass spectrometry and mass chromatography.

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Chemical structures of metabolites of dibutyl N-methyl-N-phenyl-phosphoramidate (I) by mycelial cells of Pyricularia oryzae were investigated and their fungicidal activity was evaluated to elucidate the role of the fungal metabolism. The major metabolite B1 was identified as butyl 3-hydroxybutyl N-methyl-N-phenylphosphoramidate (III) by the facts that the treatment of the metabolite with hydrogen chloride gave a six-membered cyclic phosphate and that the main product in the reaction mixture of butyl N-methyl-N-phenylphosphoramidochloridate and 1, 3-butandiol coincided with B₁ on gas-liquid chromatography (glc) and mass spectrometry (MS). Confirmation of a minor metabolite D to be dibutyl N-phenylphosphoramidate (II) was also made by comparison with the authentic sample of II. Thus the major pathway of the metabolism of I by P. oryzae was (ω-1)-hydroxylation of a butyl radical and the minor one was N-demethylation. The fungicidal activity of metabolite B1 was definitely lower and that of II was a little lower than I as far as the inhibitory activity on conidial germination was concerned. Since B1 is the major metabolite, the metabolism as a whole may be detoxification for P. oryzae.

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On single oral or subcutaneous administration of the alcohol- and acid-labeled preparations of [1R, trans]- and [1R, cis]-tetramethrin [3, 4, 5, 6-tetrahydrophthalimidomethyl (IRS, cis, trans-chrysanthemate] to both sexes of rats, the radiocarbon was rapidly and almost completely eliminated from the rat body. The radiocarbon residues in 20 to 21 tissues examined were generally very low. The trans-isomer showed somewhat more complete radiocarbon recovery and lower tissue residues than the cis-isomer. In addition, the acid-labeling showed slightly lower tissue residues, as compared with the alcohol-labeling. However, no significant differences in the total radiocarbon recovery and tissue residue levels between sexes or administration routes were found. Both [1R, trans]- and [1R, cis]-tetramethrin similarly underwent ester cleavage, reduction of the 1-2 bond of the alcohol moiety and oxidation at the isobutenyl group of the acid moiety and at the 2, 3, and 4-positions of the alcohol moiety. The metabolites produced via these reactions were in part conjugated with glucuronic acid. The major metabolites from the acid moiety of both isomers were the oxidized derivatives of chrysanthemic acid at the trans methyl of the isobutenyl group. Also, the major metabolites from the alcohol moiety of both isomers were the cyclohexanedicarboximide derivatives oxidized at the 2, 3 and 4-positions. However, the relative amount of the identified metabolites differed in the two both isomers. There were no remarkable differences in the nature and amounts of metabolites between either dose routes or sexes.

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Plants, soils and water were collected from Mt. Wakakusa in Nara Prefecture after the aerial application of a fenitrothion formulation for pine budworm control, and the samples were analyzed for fenitrothion and its decomposition products. Fifty percent of the fenitrothion in the applied area degraded in 2-4 days, and 2.5% remained after 144 days. In leaves of Maesa japonica, fenitrothion was detected at 78.3ppm on the day of application, but 99% disappeared within a week. After 144 days, 0.1, 0.01 and 0.001ppm were detected in grasses (mainly Zoysia japanica), and soils of the upper and lower layers, respectively. Fenitrooxon in leaves was 0.1-0.3% of the fenitrothion detected but it disappeared because of rain after 30 days. Aminofenitrothion was found in the amounts of 1-7% of detected fenitrothion in soils for a long time. In natural aquatic systems of this basin, fenitrothion was detected at 38.2ppb immediately after application, but it was reduced rapidly by dilution and then it maintained a low concentration for a long period. After 49 days fenitrothion and 3-methyl-4-nitrophenol were detected at 0.001-0.02ppb and 0.001-0.07ppb, respectively. The effusion of fenitrothion by aquatic systems from the applied area was estimated at 0.7% (1.0% in consideration of 3-methyl-4-nitrophenol) for 49 days.

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[in Japanese]

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