Sumithion (0,0-Dimethyl O-[3-methyl-4-nitrophenyl] phosphorothioate) 
Activation studies of sumithion were conducted with slices and 
tissue homogenates of mammals, insects, and plants. Ion exchange 
chromatography indicated that although the oxon analog is formed, 
desmethyl sumithion is the principal metabolite. Some phosphoric or 
thiophosphoric, dialkyl thiophosphoric and dialkyl phosphoric acids 
were also liberated (Fukami, 1963c; Miyamoto et al., 1963a, b; Mi- 
yamoto, 1964a, b; Vardanis and Crawford, 1964). 
After exposure of rats and guinea pigs to sumithion, the desmethyl 
analog, dimethyl phosphorothioate, dimethyl phosphate, and four uniden- 
tified compounds were found (Miyamoto et al., 1963a, b). 
When P32-labeled sumithion was applied to rice plants at the pre- 
heading stage, the sumithion penetrated into the tissues and was rapidly 
degraded to desmethylsumithion, dimethyl phosphorothioic acid and phos- 
phorothionic acid. Sumioxon was present and minute amounts of such de- 
gradation products as dimethyl phosphorothioic acid, phosphorothionic 
acid and free p-nitrocresol were identified. The latter compound was 
also found in cocoa beans exposed to sumithion (Miyamoto and Sato, 
1965a, b). 
When German cockroaches were treated with sumithion, the desmethyl 
analog was found (Miyamoto et al., 1963a, b). 
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