Correlation of acetylcholinesterase activity inhibition with ageing in organophosphate-exposed farm workers at Ibadan, South-Western Nigeria

Abstract

Background/Aim: In an attempt to destroy pests and enhance food production, Nigerian local farmers are occupationally exposed to organophosphate pesticides (OP). During exposure, OP affect the nervous system by impairing the activity of acetylcholinesterase enzyme (AchE) thus leading to accumulation of acetylcholine at the neuromuscular junction. This defect in the cholinergic pathway has been consistently reported for over two decades in studies on the brains of those with advanced age. This study is aimed at determining the relationship between the levels of AchE activity with ageing in apparently healthy OP-exposed farmers as well as in unexposed controls in Nigeria due to paucity of data in this environment. Method: This case-control study comprises a total of 104 apparently healthy participants. Fifty-two farmers (41 males, 11 females; aged 30-62 years) occupationally exposed to OP and 52 sex-matched unexposed controls (aged 38-60 years) were recruited from Idi-Ayunre farm settlements on the outskirts of Ibadan and University College Hospital, Ibadan respectively. Results: Mean AchE level of OP-exposed farmers (7.22 ± 1.99 klU/L) was significantly lower (p<0.05) than the controls (12.23 ± 1.67 klU/L). Correlation of AchE activity with age was 0.189, p=0.179 and - 0.325, p=0.019 for the farmers and controls respectively. Conclusion: Low AchE activity level of the farmers indicates a persistent accumulation of acetylcholine at the neuromuscular junction, which may predispose them to intermediate syndrome. Significant negative correlation between AchE activity and age of the controls probably indicates that the normal ageing process is associated with decreased AchE activity.