Cholinesterase status of some Ethiopian state farm workers exposed to organophosphate pesticides

The effects of organophosphate (OP) pesticide exposure on cholinesterase (ChE) activities were assessed in relation to occupational factors by studying 430 pest control workers from three state farms and 161 comparable controls. Plasma cholinesterase (PChE) and erythrpcyte cholinesterase (AChE) activities were determined by an electrometric method. Plasma alkaline phosphatase (AP) and glutamic pyruvic transaminase (GPT) were estimated colorimetrically by using diagnostic kits 6391 and 1442520 respectively. Information on OP poisoning symptoms and related occupational factors were collected based on the WHO recommendations. Pest control workers had significantly lower PChE and AChE activities than the controls (P<0.001). In addition, 58 (13.5%) and 47 (10.9%) of the exposed workers had PChE and AChE activities below the lower limits of the controls respectively. Normal plasma AP and GPT values without significant difference from the controls were noted. Among the exposed population, the "spray men" and those who were exposed for 5 years or less were found to be the most affected groups. Although poisoning symptoms were more frequent in the exposed workers than in the controls, only sweating was found to have an association with a significant reduction in AChE activities (P<0.05). The study revealed that the health risks are more apparent in the exposed workers and are of immediate concern. Pre-placement and periodic medical examination and creation of swareness among the exposed population are recommended to minimize the problem.