OBJECTIVETo study the effect of dimethoate on the expression of heat shock protein 70 (HSP70) in peripheral blood lymphocytes of human beings and to explore the feasibility of HSP70 in biomonitoring among workers exposed to organophosphorous pesticides.

METHODSPeripheral blood lymphocytes were isolated from subjects, comprising 11 people of the control group and 35 workers of the exposure group exposed to dimethoate. Flow cytometry was used for detecting both the basic level and the level of the dimethoate-induced expression of HSP70. The activity of whole blood acetylcholinesterase (AChE) was examined at the same time. Then the potential influential factors to HSP70 expression and AChE activity were analyzed.

RESULTSThe basic level of HSP70 expression in the exposure group and the control group was 41.24% +/- 10.45% and 23.97% +/- 4.29% respectively. The activity of AChE in these two groups were (125.23 +/- 7.97) and (145.36 +/- 8.78) U/ml respectively. Both differences were statistically significant (P < 0.01). Among the exposure group, the basic level of HSP70 expression of the two categories comprising operators and packers, were 47.34% +/- 11.87% and 38.05% +/- 8.20% respectively (P < 0.05), while there was no significant difference (P > 0.05) in AChE activity between these two categories. The factors that had significant influence on the HSP70 basic level of the exposure group were the health condition, the environmental concentration of dimethoate and the exposure time in order, according to their significance of influence. At least 88% variance of HSP70 could be explained by these factors. The only factor that could influence AChE activity significantly was the exposure time, and it could only explain about 12% variance of AChE activity. After the treatment of dimethoate in vitro, the level of the induced expression of HSP70 in the control group was significantly higher than that of the exposure group (P < 0.01). The increasing order was the control group, the group of packers and the group of operators according to the increasing extent and there were significant difference among them (P < 0.01). The factors that could significantly influence the change ratio of HSP70 expression were the environmental concentration and the exposure time.

CONCLUSIONHSP70 is a potential index that can reflect the individual and environmental conditions of workers exposed to dimethoate comprehensively.