Objective: 

The purpose of the present study was to use the modified electrometric technique for measuring blood ChE in workers exposed to the organophosphate and carbamate insecticides in Kirkuk, Iraq.

Methods: 

ChE activities in whole blood of male workers (n = 40) who were exposed to organophosphate and carbamate insecticides, for a duration of more than five years and non-exposed healthy male volunteers (n =[?]12) were measured by an electrometric method; The pH (pH1) of the mixture was measured, and then 0.1 ml of 7.5% of acetylcholine iodide, as a substrate, was added. The reaction mixture was incubated at 37°C for 20 minutes. The pH (pH2) of the reaction mixture was measured after the end of the incubation period. Enzyme activity was expressed as DpH/20 min =[?]pH1-pH2 -[?](DpH of the blank). The blank was without the blood sample.

Results: 

Mean values of ChE activities (DpH/20 min) in the whole blood of healthy non-exposed subjects and workers were 1.41and 1.2, respectively. Ten minutes after in vitro addition of quinidine sulfate to inhibit pseudo cholinesterase activity in the blood, the estimated true cholinesterase activities in exposed workers and non-exposed individuals were 0.08 and 0.07 DpH/20 min, respectively.

Whole blood ChE activities of the exposed workers were significantly lower than those of healthy individuals.

Conclusions: 

These findings are the first collective report of human and whole blood cholinesterase activities as determined by the modified electrometric method and extend the usefulness of this method by detecting ChE inhibition after exposing to the organophosphate and carbamate insecticides.