One of the new organic-phosphorus insecticides now being investigated is dimethoate, 
Studies of the metabolism of this compound, using P32 tagged material, have suggested 
the metabolic pathway shown: 
0 p ies S 
BO | ] CH,0 I CH | 
_ FSH CNHCH, <—— ~  >P-S-CH,CHNCH, —> P-SH 
HO 2 cH,0 cH,0 
S : 
CHO T CH_O I 
3° p-SCH..COOH oS ~f Wi cGul GENGH== eo) SEA 
2 ees 
cH,0 cl 
~ H,0 OH, 
cHS 
Yo a 
W 
A -0 
» SCH, COOH ——> = sh H 
As observed in other compounds of this type, the oxygen analog is a more potent 
esterase inhibitor than the parent compound. However, the difference is not great, and 
none of the other metabolites inhibit cholinesterase, 
The breakdown products appear to be the same in plants and animals. No informa- 
tion has been published on the fate of this compound in soils, 
CARBAMATES 
A recently developed carbamate, 1-naphthyl methylcarbamate (Sevin), is showing 
great promise for the control of many insects. It is interesting to note that several 
carbamates are used as plant-growth regulators, Sevin is hydrolyzed to 1-naphthol in 
plants and animals, but the 1-naphthol is not sufficiently stable to permit the detection of 
more than trace amounts, The metabolic process apparently starts with hydrolysis, thus: 
rei 
ll 
O-C-N-CH, OH + CO p+ CH,NH, 
6 ea meee’ f 
Sevin 1-naphthol 
The extent and rate of hydrolysis have not been determined, but the rate is apparently 
slow under most conditions, Under alkaline conditions, however, hydrolysis is rapid and 
complete. 
PERSISTENCE OF INSECTICIDES 
One of the chief items of interest in the study of insecticide residues is a study of 
their persistence under the conditions of use, To determine this, at appropriate intervals 
110 
