Neuropsychological sequelae from acute poisoning and long-term exposure to carbamate and organophosphate pesticides

This research examines the effects of different degrees of pesticide exposure on neuropsychological performance. Exposures varied from acute poisoning coupled with chronic exposure to low or high levels of chronic exposure (defined by years of exposure). A cross-sectional neuropsychological and biochemical study was conducted in greenhouse farmers from southern Spain: data from 24 acutely poisoned workers and 40 non-poisoned but chronically (low or high) exposed sprayers were compared to 26 controls. We examined performance on 21 neuropsychological tests that assessed attention, memory, praxis, gnosis, motor coordination, naming and reasoning and also examined values of plasmatic cholinesterase. Results indicated statistically significant neuropsychological deficits in the acute poisoning and high chronic exposure groups after controlling for confounds, whereas similar performance was seen in the low chronic exposed subjects and controls. Subjects who were acutely poisoned performed worse than the other groups on perceptual, visuomotor, visual memory and mood state domains. Both the acutely poisoned and the chronically high exposed subjects obtained significantly lower scores in the perceptual, verbal memory and visuomotor domains. Levels of butyrylcholinesterase were related to the seasonal sprayer activity except in the case of acutely poisoned subjects. Conclusions: Both acutely poisoned long-term workers and chronically high (> 10 years) exposed workers exhibited similar disturbances in perception and visuo-motor processing, in the absence of any related acute effect of butyrylcholinesterase inhibition. In the case of acutely poisoned subjects, verbal and perceptive learning and recall and constructive abilities were also impaired. These results point to the need for follow-up studies to assess the possible sequelae of chronic and acute exposure to pesticides and their interactions.