Factors influencing plasma butyrylcholinesterase activity in agricultural workers.

We studied the influence of some factors on plasma butyrylcholinesterase activity (BChE) and we assessed the health status of agricultural workers and looked for the effects of chronic exposure to pesticides, in the aim to determinate factors that must be considered for interpretation of BChE, for occupational monitoring of workers exposed to pesticides. The study was carried out in 110 workers from the Sahel region of Tunisia exposed to pesticides and in 97 controls. All individuals have undergone clinical examination. BChE activity was measured by spectrophotometric method. The mean of BChE activity of workers was significantly lower than that of control group (P < 0.001). Among the 44% of farmworkers with at least one neurologic or neuropsychic symptom, 29% had BChE activity lower than 6000 IU/L. Headache was observed in 20% of workers. Ancientness of exposure equal to 10 years or more, last exposure dates back to 60 days or less, exposure for 2 days or more per week, exposure exceeding 150 h per year and to organophosphorus-carbamates mixture were implicated in significant decreases of BChE activity and can be considered as risk factors of cholinergic toxic effects. Thus, BChE activity is a useful indicator to monitor workers chronically exposed to pesticides. However, it should be accompanied by periodical health examination, taking into account risk factors, for an early identification of workers at increased risk.