Neuropsychological effects of long-term exposure to organophosphate pesticides

Cholinesterase inhibitors, such as carbamates and organophosphates (OPs), are widely used as insecticides and pesticides and may be stored as biological weapons. The massive use of these products, along with a lack of personal protective equipment on the job, and accidental and intentional ingestions, has produced a great number of poisonings in farmers. A large part of the employment and income in southeastern Spain is concentrated in intensive greenhouse agriculture in which growers are exposed to a varying degree of subsymptomatic doses of a combination of pesticides, mainly OPs and carbamates. We conducted a cross-sectional survey of workers in high-exposure conditions to assess possible neurobehavioral deficits, using a wide array of tasks to test neuropsychological functioning and emotional status. Linear and logistic regression series revealed the importance of the variable years working with pesticides as a measure of cumulative exposure for risk of worsened perceptive function performance (odds ratio (OR)=6.93, 95% confidence interval (CI): 1.52-31.51), visuomotor praxis (OR=5.00, 95% CI: 1.22-20.40) and integrative task performance time (OR=4.12, 95% CI:1.18-14.39) with no relation to plasma cholinesterase activity as a measure of recent exposure. This association was statistically significant after controlling for confounds (age and educational level). The findings showed association of long-term exposure and worse performance in neuropsychological functions, which is interpreted as evidence of a chronic effect of cumulative high exposure to OPs and carbamates. (c) 2004 Elsevier Inc. All rights reserved.