Introduction:Organophosphate and carbamate insecticides pose major environmental pollution problems and
health hazards to people and animals. These insecticides inhibit cholinesterase (ChE) activity in the nervous
tissues and neuromuscular junctions. The measurement of blood ChE is a useful tool for monitoring exposure to
organophosphate and carbamate insecticides. The purpose of the present study was to use a modified
electrometric technique for measuring blood ChE in workers exposed to the organophosphate and carbamate
insecticides in Kirkuk, Iraq.
Method: A modified electrometric method was used to measure ChE activity in the whole blood of male workers
(n = 40) exposed to organophosphate and carbamate insecticides, for a duration of not less than six years.
Healthy male volunteers (n =12) not exposed to insecticides served as controls. Following in vitro inhibition of
pseudo cholinesterase by quinidine sulfate, true cholinesterase activity was estimated in the blood of the subjects.
After in vitro addition of the organophosphate (chlorpyrifos and methidathion, 0.5 and 1 µM) and carbamate
(carbaryl, 5 and 10 µM) insecticides to the reaction mixtures, inhibitions of blood ChE were also determined.
Results: Mean values of ChE activities (pH/20 min) in the whole blood of healthy non-exposed subjects and
insecticide-exposed workers were 1.41and 1.2, respectively. Whole blood ChE activities of the exposed workers
was significantly lower than those of healthy individuals.
Conclusions: These findings indicate the usefulness of the modified electrometric method for monitoring blood
ChE activity in insecticide-exposed workers and there was a significant effect of these Organophosphate and
carbamate insecticides on the activity of Ach esterase in workers blood. .