
Diazinon [0,0-diethyl 0-(2-isopropyl-4-methy1l-6-pyrimidiny1) 
phosphorothioate ] 
Studies with mice and insects have been conducted. The only metabolite 
identified was the P = 0 analog (466, 596, 840). In cows, the diethyl- 
phosphorothioic and phosphoric acids were found (1220). 
Fish (Fundulus heteroclitus L.) and freshwater mussels (Elliptio 
complanatus Solander) were exposed to diazinon-C!* contaminated waters. 
Only diazinon was detected in the fish. It was assumed that some of the 
labeled portion was split off and metabolized to clo, (1006). 
Tomato plants grown in a fenced and controlled plot were sprayed with 
S3°-diazinon. The only metabolite identified was oxo-diazinon (diazoxon). 
After spraying with C!+-diazinon, 2-isopropyl-4-methylpyrimidin-6-o0l was 
found. The formation of radioactive barium carbonate was evidence that the 
pyrimidine ring of diazinon was degraded by tomato plants (1149, 1616). In 
wheat grain and bean plants (Phaseolus vulgaris) treated with diazinon, small 
amounts of 2-isopropyl-4-methylpyrimidin-6-o0l and unextractable metabolites 
were observed. Diazinon was not found after 30 days (756, 1573). On treated 
spinach, high residue levels of the pyrimidinol and oxon metabolites were 
observed (1616). An alteration product of diazinon was isolated from field 
sprayed kale that exhibited retention times on two GLC columns and an R¢ value 
on TLC identical with those of 0,0-diethyl-0[2-(2'-hydroxy-2'-propy1l)-4-methyl- 
6-pyrimidinyl]phosphorothioate, a compound prepared by ultraviolet irradiation 
of diazinon. Tentative identification was made by infrared and mass spectros- 
copy (1646). 
Pseudomonas melophthora and Trichoderma viride degraded diazinon but 
no metabolites were identified (145, 1622). When diazinon was incubated 
with streptomyces or arthrobacter individually, the pyrimidyl ring was not 
attacked; however, when these two organisms were incubated together, they 
metabolized the ring of diazinon. Two metabolites were observed but not 
identified (576). 
In soil, hydrolysis was a major mechanism in diazinon degradation 
(822). Three weeks after treatment of Sultan silt loam with diazinon, 
in addition to diazinon, 2-isopropyl-4-methyl-6-hydroxypyrimidine was 
identified. The oxon analog was unstable in soil and was not detected. 
When C!4-ring-labeled diazinon was used, C!"0, was produced (542). 
The effect of soil microorganisms, moisture and type and diazinon 
concentration on the disappearance rate of diazinon was studied. Results 
indicated that all four factors influenced the degradation rate, micro- 
organisms having the greatest effect and diazinon concentration the least. 
Diazinon half-life varied from 21.6 days to 80.2 days (1555). 
143 

