p-nitrophenol was excreted in the urine (Gardocki and Hazelton, 1951; 
Elliott et al., 1960). In cattle, however, conjugated p-aminophenol 
was excreted in the urine, probably the result of the ability of rumen 
organisms to reduce parathion to amino parathion. 
Studies with insects indicated similar paths of metabolism, via 
paraoxon and/or dealkylation, but at varying rates (Metcalf and March, 
1949; Lockau and Ludicke, 1952; Krueger et al., 1960; O'Brien and Smith, 
196la; Plapp et al., 1961; Shishido and Fukami, 1963; Fukami and 
Shishido, 1963b; Miyamoto et al., 1963b; Matsumura and Hogendjk, 1964). 
In larvae of the rice stem borer, ethyl parathion, ethyl paraoxon, 
diethyl thiophosphate, and diethyl phosphate were found after topical 
application (Kojima et al., 1963b, c). 
Hydrolytic studies indicated there was no catalysis by [Ht]. 
For parathion: k = 0.047 [OH7] +4 x 1076 min7! (25°C.) 
and k = 0.14 [OH7] +1.5 x 1079 min! (35°C.) 
in 0.001N to 0.50N - NaOH 
50% = 120 days in the absence of alkali (pH <10) (Peck, 1948). 
In soils of low numbers of microorganism (autoclaved soil) or of 
low microorganism activity (dry soils), parathion persisted for a rel- 
atively long time. No aminoparathion was found in autoclaved soils. 
Yeast was primarily responsible for reduction of parathion in soil to 
aminoparathion; bacteria had no effect on this reduction (Lichtenstein 
and Schulz, 1964). 
134 
