| Association of Pesticide Exposure with Neurologic Dysfunction and Disease Freya Kamel and Jane A. Hoppin National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, USA Abstract
Poisoning by acute high-level exposure to certain pesticides has well-known neurotoxic effects, but whether chronic exposure to moderate levels of pesticides is also neurotoxic is more controversial. Most studies of moderate pesticide exposure have found increased prevalence of neurologic symptoms and changes in neurobehavioral performance, reflecting cognitive and psychomotor dysfunction. There is less evidence that moderate exposure is related to deficits in sensory or motor function or peripheral nerve conduction, but fewer studies have considered these outcomes. It is possible that the most sensitive manifestation of pesticide neurotoxicity is a general malaise lacking in specificity and related to mild cognitive dysfunction, similar to that described for Gulf War syndrome. Most studies have focused on organophosphate insecticides, but some found neurotoxic effects from other pesticides, including fungicides, fumigants, and organochlorine and carbamate insecticides. Pesticide exposure may also be associated with increased risk of Parkinson disease ; several classes of pesticides, including insecticides, herbicides, and fungicides, have been implicated. Studies of other neurodegenerative diseases are limited and inconclusive. Future studies will need to improve assessment of pesticide exposure in individuals and consider the role of genetic susceptibility. More studies of pesticides other than organophosphates are needed. Major unresolved issues include the relative importance of acute and chronic exposure, the effect of moderate exposure in the absence of poisoning, and the relationship of pesticide-related neurotoxicity to neurodegenerative disease. Key words: fumigant, fungicide, insecticide, neurobehavioral performance, neurodegenerative disease, neurologic symptoms, organophosphate, Parkinson disease, pesticide. Environ Health Perspect 112:950-958 (2004) . doi:10.1289/ehp.7135 available via http://dx.doi.org/ [Online 20 May 2004]
Address correspondence to F. Kamel, Epidemiology Branch, MD A3-05, NIEHS Box 12233, Research Triangle Park, NC 27709. Telephone: (919) 541-1581. Fax: (919) 541-2511. E-mail: kamel@niehs.nih.gov We appreciate the thoughtful comments of D. Baird and M. Longnecker on an earlier version of this paper. This work was supported by internal funding to the Epidemiology Branch, NIEHS. The authors declare they have no competing financial interests. Received 30 March 2004 ; accepted 19 May 2004.
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