The method for analysis of residues of MCPH (2-methyl-4-chlorophenoxyaceto hydrazide) and MBPMC (4-methyl-2, 6-di-tert-butylphenyl-N-methylcarbamate) in soil was established by using gaschromatograph, equipped with an electron capture detector. The prosidure is as follows: (1) Residue of MCPH in soil was extracted with acetone under the condition of below pH 1, and the extract was hydrolyzed with 20% hydrochloric acid at 75°C for 30min. The hydrolysate was esterificated with trifluoroethanol by using boron-trifluorid ether complex as catalyst at 80°C for 1hr. The esterized product was analyzed by gaschromatography. (2) Residue of MBPMC in soil was extracted with methanol, and acetylated with trifluoroacetic anhydrid for 48hr at room temperature after cleaned up by Florisil column chlomatography. The acetylated product determined by gas chlomatography. In MCPH, the recoveries from the samples fortified at the levels of 3.6ppm to 0.36ppm were ranged from 100% to 101%, and in MBPMC, the recoveries from the samples fortified at the levels of 5ppm to 0.5ppm derived from 94% to 98%.

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The degradation of 3-(3-chloro-4-chlorodifluoromethylthiophenyl)-1, 1-dimethylurea (Clearcide^®) in paddy soils on which rice plants were planted under flooded conditions was investigated in accordance with growth stages of rice plants by using ¹⁴C-Clearcide labeled at 1, 1-dimethyl and unlabeled Clearcide. At the end of the growth stage periods of rice plants, the soil was sampled and extracted with 80% acetonitrile and partitioned into organic, aqueous and unextracted fractions. Each fraction was subjected to radioactivity assay, tlc and glc.
More than 50% of radioactivity was detected in the chloroform soluble fraction even after the lapse of time and the activity in the water soluble fraction was negligible (maximum detected value was 2.7%). Detected compounds from the acetonitrile extracts were mainly parent Clearcide and small amounts of degradation products.
Desmethyl Clearcide and Clearcide sulfoxide and its sulfone were identified as major degradation products, and desmethyl Clearcide sulfoxide, its sulfone and aniline derivatives were also identified. Small amounts of three unknown degradation products were found with the lapse of time. Half life period of Clearcide in paddy soils was about 30 to 40 days.

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A single intraperitoneal injection of fenitrothion (100mg/kg) to mice brought a biphasic effect on microsomal drug metabolism and cytochrome P-450 content. A slight decrease in protoheme was observed, whereas fenitrothion did not affect microsomal Cytochrome b₅ content.
Pretreatment of mice with SKF 525-A, an inhibitor of drug metabolism, afforded some prevention against the decrease in cytochrome P-450 owing to fenitrothion injection. On the other hand, there was the marked decrease in cytochrome P-450 when some organothiophosphates were incubated with microsomes under the presence of NADPH-generating system in vitro. The decrease was observed as long as organophosphates contained P=S group.
These results reveal that the depression of cytochrome P-450 in an earlier stage might be coupled with the oxidative metabolism of sulfur compound. Recovery from the decrease in cytochrome P-450, which ordinary take place within 24hr, was delayed by the concomitant treatment of mice with cobalt chloride indicating that the heme synthesis may be involved in recovery and rebounded increase in cytochrome P-450 in the later stage after the treatment with fenitrothion.

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Metabolic fate of a ureid herbicide, 1-(α, α-dimethybenzyl)-3-(p-tolyl) urea, dimuron, was investigated in male rats. Greater than 69% of orally administered carbonyl-¹⁴C-dimuron (50mg/kg, single) was absorbed from the gastrointestinal tract of male Wistar rats. Furthermore, the dose was entirely eliminated in the feces (66%) and urine (34%) within 48hr after dosing. Tissue retention accounted for only 0.6% of the dose within 48hr after administration. Radiocarbon levels in selected tissues declined to less than detectable levels (liver: 0.2ppm, kidney: 0.03ppm, adipose tissue: 0.15ppm, blood: 0.025ppm, plasma: 0.02ppm, carcass: 0.05ppm equivalent of dimuron) after 120hr. The high elimination observed in the feces was mainly due to active biliary excretion (38.6% in 48hr). A substantial part (24.3%) of the radioactive biliary excreta was reexcreted into the bile through an enterohepatic cycle. In addition to urinary and biliary excretion, the involvement of the gastrointestinal tract was observed as a minor excretion route of dimuron. Tlc of the urine extracts indicated that dimuron was metabolized to more than seven polar metabolites, but dimuron itself was not detected in the urine. From fecal extracts, dimuron and several of its metabolites were detected. A major metabolite found in the urine was suggested as 1-(α, α-dimethylbenzyl)-3-(p-carboxyphenyl) urea by Tlc. As minor metabolites, p-toluidine was detected in the urine, and the expiration of radioactive carbon dioxide was also observed (less than 0.06% of the dose). Furthermore, radioactive β-glucuronide conjugate was detected in the bile.

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Intraperitoneal toxicity in mice of fenitrothion (Sumithion^®) derivatives oxidized at 3-methyl group such as 3-hydroxymethylfenitrothion and 3-formylfenitrothion was higher than fenitrothion. Their oxygen analogs were more toxic than fenitrooxon, consistent with even more potent inhibitory activity on bovine erythrocyte cholinesterase. In contrast, insecticidal activity of these compounds, whether phosphorothioate or phosphate, was much less than fenitrothion. S-Methylfenitrothion was less noxious than fenitrooxon to mice. Amino analogs of fenitrothion and fenitrooxon and their derivatives were less toxic than fenitrothion.
To killifish all the degradation products except 3-methyl-4-aminophenol were less hazardous than fenitrothion, and to daphnia fenitrothion and fenitrooxon were most toxic. Mutagenic activity of the fenitrothion derivatives on Salmonella typhimurium was negative, except 3-hydroxymethylfenitrothion, regardless of the presence or absence of mammalian hepatic metabolizing enzymes.

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Degradation and movement of (+)-trans and (+)-cis isomers of permethrin [3-phenoxybenzyl (±)-cis, trans-3-(2, 2-dichlorovinyl)-2, 2-dimethylcyclopropanecarboxylate] in soil were studied under laboratory conditions. When (+)-trans and (+)-cis isomers of permethrin labeled with ¹⁴C in the alcohol or acid moiety were applied to two types of soil (Kodaira and Azuchi) at the rate of 1.0ppm and held at 25°C in the dark under upland conditions, both isomers were rapidly decomposed with the half-lives of 6 to 12 days. The degradation rate of (+)-trans isomer was slightly faster than that of (+)-cis isomer in both soils. Major degradation products from both isomers were 3-(4′-hydroxyphenoxy)benzyl-3-(2, 2-dichlorovinyl)-2, 2-dimethylcyclopropanecarboxylate, 3-phenoxybenzyl alcohol, 3-phenoxybenzoic acid, 3-(2, 2-dichlorovinyl)-2, 2-dimethylcyclopropanecarboxylic acid, and its hydroxylation derivatives.
Although both (+)-trans and (+)-cis-permethrin hardly moved through the soil with water, the degradation products such as 3-phenoxybenzoic acid, 3-(4′-hydroxyphenoxy)benzyl-3-(2, 2-dichlorovinyl)-2, 2-dimethylcyclopropanecarboxylate were slightly eluted with water.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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