Cholinesterase activities of workers exposed to organophosphorus insecticides in Pakistan and Haiti and an evaluation of the tintometric method.

Five reference laboratories were established in Pakistan for monitoring cholinesterase (ChE) activities of workers exposed to organophosphorus compounds. ChE activities were determined by the Michel and tintometric method. Observations of ChE activities were made during two malaria seasons. The first season showed that although a significant depression of cholinesterase occurred among some of the workers, the ChE activities of workers were within the normal range during the following season. The reason for the difference is discussed. Similar studies were undertaken in Haiti. Mean and standard deviations (SD) were calculated for comparison of the tintometric versus the Michel method. The data show a correlation between the methods. For further evaluation of the tintometric method, organophosphorus and oxon analog inhibition of cholinesterase were determined in vitro. The tabulated data show that the tintometric method is adequate for determining whether a worker is exposed to dangerous amounts of insecticides.