Biochemical Impact of Pesticide Exposure on Cholinesterase Activity in Farmers in Kogi State

Organophosphate and carbamate pesticides are widely used in crop farming across Kogi State, and their inhibitory effect on acetylcholinesterase activity serves as a biomarker of systemic pesticide exposure in agricultural workers. This study evaluates cholinesterase activity in blood as a biomarker of pesticide exposure in smallholder crop farmers in Lokoja LGA, Kogi State. Fifty active pesticide-using farmers and forty non-farmer community members serving as controls were recruited during the active farming season. Structured interviews captured pesticide types used, frequency of application, protective equipment use, and duration of farming experience. Whole blood acetylcholinesterase (AChE) and plasma butyrylcholinesterase (BChE) activities were measured by the Ellman colorimetric method. Red blood cell count and haemoglobin were also determined. Results show significantly reduced AChE activity in farmers compared to controls (mean: 3.21 vs 6.42 kU/L), with 58 percent of farmers showing AChE activity below 70 percent of the control mean, indicative of significant exposure. BChE activity was similarly reduced. Farmers who reported using organophosphate pesticides without protective gloves showed the most severe cholinesterase depression. Duration of farming and frequency of pesticide application correlated negatively with cholinesterase activities. No significant relationship was found between educational level and protective equipment use. The study recommends mandatory cholinesterase surveillance and pesticide safety training for farmers in Kogi State, and advocates for regulation of the most toxic organophosphate formulations in smallholder agricultural markets. Keywords: cholinesterase, pesticide exposure, organophosphate, farmers, Kogi State.