When roots of wheat plants were treated with parathion solutions, 
the leaf guttation fluid contained an active anticholinesterase which was 
shown to be paraoxon. 
Application of parathion and paraoxon to the skin of man, cat, 
rabbit, and rat showed that only the paraoxon was hydrolyzed (Jensen and 
Peterson, 1952; Fredriksson et al., 196la,c). In man, the only metabolite 
that has been identified is p-nitrophenol in urine (Lieben et al., 1953; 
Funckes et al., 1963). More extensive studies with labeled parathion 
conducted with rats showed that highest levels of radioactivity appeared 
in the salivery glands and cervical brown fat. Liver, kidney, and 
adipose tissues also showed high radioactivity. Labeled material was 
excreted mainly by the kidneys and not in bile (Fredriksson and Bigelow, 
1961b). 
Other studies with rats have shown that parathion metabolism pro- 
ceeded via de-ethylation as well as paraoxon (Diggle, 1951; Gersman et al, 
1952; Myers et al., 1952; Aldridge, 1953; Davison, 1954; Kubistova, 1959; 
Fukami and Shishido, 1963a, b; Miyamoto et al., 1963a; Brindley and Dahn, 
1964). Mono- and dimethyl phosphoric, dimethyl thiophosphoric, thio- 
phosphoric, and phosphoric acids were also observed (Miyamoto et al., 
1963a, b; Miyamoto, 1964a, b; Vardanis, 1964). 
When parathion was incubated with bovine rumen fluid, paraoxon, 
amino parathion, and amino paraoxon were produced along with diethyl 
phosphoric and phosphorothioic acids (Cook et al., 1957b; Pankaskie et al., 
1952; Ahmed et al., 1958b). In the case of nonruminating mammals, 
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