| Pesticides and Parkinson's Disease--Is There a Link? Terry P. Brown,1 Paul C. Rumsby,2 Alexander C. Capleton,1 Lesley Rushton,1 and Leonard S. Levy1 1Medical Research Council Institute for Environment and Health,University of Leicester, Leicester, United Kingdom; 2National Centre for Environmental Toxicology, WRc-NSF Ltd., Medmenham, Marlow, United Kingdom Abstract
Parkinson's disease (PD) is an idiopathic disease of the nervous system characterized by progressive tremor, bradykinesia, rigidity, and postural instability. It has been postulated that exogenous toxicants, including pesticides, might be involved in the etiology of PD. In this article we present a comprehensive review of the published epidemiologic and toxicologic literature and critically evaluate whether a relationship exists between pesticide exposure and PD. From the epidemiologic literature, there does appear to be a relatively consistent relationship between pesticide exposure and PD. This relationship appears strongest for exposure to herbicides and insecticides, and after long durations of exposure. Toxicologic data suggest that paraquat and rotenone may have neurotoxic actions that potentially play a role in the development of PD, with limited data for other pesticides. However, both the epidemiology and toxicology studies were limited by methodologic weaknesses. Particular issues of current and future interest include multiple exposures (both pesticides and other exogenous toxicants) , developmental exposures, and gene-environment interactions. At present, the weight of evidence is sufficient to conclude that a generic association between pesticide exposure and PD exists but is insufficient for concluding that this is a causal relationship or that such a relationship exists for any particular pesticide compound or combined pesticide and other exogenous toxicant exposure. Key words: epidemiology, literature review, Parkinson's disease, pesticides, toxicology. Environ Health Perspect 114:156-164 (2006) . doi:10.1289/ehp.8095 available via http://dx.doi.org/ [Online 7 September 2005]
Address correspondence to A.C. Capleton, MRC Institute for Environment and Health, University of Leicester, 94 Regent Rd., Leicester, LE1 7DD, UK. Telephone: 44-0-116-223-1606. Fax: 44-0-116-223-1601. E-mail: acc8@leicester.ac.uk Supplementary Material is available online at http://ehp.niehs.nih.gov/docs/2005/8095/supplemental.pdf We thank K. Bradley for conducting the literature searches, J. Peters for drawing the forest plots, and H. Pall, D. Ray, and A. Spurgeon for reviewing the original manuscript. This study was funded by the Department for Environment, Food, and Rural Affairs. The authors declare they have no competing financial interests. Received 7 March 2005 ; accepted 7 September 2005.
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