Sumithion (Fenitrothion) [0,0-Dimethyl 0-(3-methy1-4-nitropheny1) 
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 thio- 
phosphoric and dialkyl phosphoric acids were also liberated (1016, 1017, 
LO21,,-022.,. 1443:,.-16:8:7)* 
After exposure of rats and guinea pigs to sumithion, the desmethyl 
analog, dimethyl phosphorothioate, dimethyl phosphate, and four unidenti- 
fied compounds were found (1021, 1022). 
Urine and feces, from male Swiss mice fed p32 labeled sumithion, was 
collected and chromatographed on paper. Dimethyl phosphate was the major 
metabolite found at all dosage levels. In addition to this, six compounds 
were observed and identified as orthophosphate, methyl phosphate, sumioxon, 
dimethyl phosphorothioate, desmethyl sumioxon and desmethyl sumithion. An 
eighth compound was observed but not identified (682). 
A 3% dust of sumithion, at the rate of 100 mg/kg/day for 50 - 90 
days was administered orally to cattle, sheep, and pigs. No sumithion 
residues were detected in the milk but large amounts of sumithion, sumi- 
oxon, and p-nitrocresol were found in the urine of milk cows, steers, and 
sheep. When a 254 emulsion of sumithion was administered orally at the 
rate of 10 mg actual sumithion/kg/day for five days to milk cows, small 
amounts of sumithion and sumioxon were found in the milk (1071). In other 
studies with Jersey cows, aminosumithion was also found in the milk (1583). 
(This could have been formed by rumen bacteria.) 
P32 labeled sumithion was applied topically on the pronotum of 2-day 
old female flies, both resistant and non-resistant. Resistant flies de- 
toxified sumithion at a more rapid rate than susceptible flies. However, 
there was no qualitative difference in the metabolites found. In addition 
to one unidentified compound, orthophosphate, mono- and di-methyl phosphate, 
sumioxon, phosphorothioate, dimethyl phosphorothioate, desmethyl sumioxon, 
and desmethyl sumithion were found (683). 
Studies with Bacillus subtilis, isolated from polluted water samples, 
showed that it was capable of inactivating sumithion by reduction of its 
nitro group. The metabolite was identified as amino-sumithion (1529). 
pase BE 
