Abstract
In order to clarify the effect of chlorpyrifos on workers using chlorpyrifos for termite control, changes in the cholinesterase activity in the blood of 6 workers was surveyed. Cholinesterase activity in the plasma and erythrocytes decreased in the busy season from May to September and recovered in the off season of January. The ratio of the lowest level of plasma cholinesterase activity from a worker in the busy season to the average activities of a worker examined several times in the off season, was examined in each workers. The ratio was under 50% in 6 workers using chlorpyrifos. The ratio of the mean cholinesterase activity in the erythrocytes of a worker in the busy season to that in the off season was examined, and was about 70% in 6 workers. A negative correlation between working time and increasing ratio of plasma cholinesterase was significant. A marked change in the subjective and objective symptoms of workers was not absent in busy season. Although some workers showed a decrease in the number of erythrocytes and leukocytes, and an increase in serum lipase activities, and abnormalities in the serum lipids. The data indicated that plasma cholinesterase activity levels are useful for biological exposure monitoring of chlorpyrifos.
