title: Exposure to pesticides or solvents and risk of Parkinson disease.
abstract: OBJECTIVE
  To investigate the risk of Parkinson disease (PD) associated with exposure to pesticides and solvents using meta-analyses of data from cohort and case-control studies.
  
  
  METHODS
  Prospective cohort and case-control studies providing risk and precision estimates relating PD to exposure to pesticides or solvents or to proxies of exposure were considered eligible. The heterogeneity in risk estimates associated with objective study quality was also investigated.
  
  
  RESULTS
  A total of 104 studies/3,087 citations fulfilled inclusion criteria for meta-analysis. In prospective studies, study quality was not a source of heterogeneity. PD was associated with farming and the association with pesticides was highly significant in the studies in which PD diagnosis was self-reported. In case-control studies, study quality appeared to be a source of heterogeneity in risk estimates for some exposures. Higher study quality was frequently associated with a reduction in heterogeneity. In high-quality case-control studies, PD risk was increased by exposure to any-type pesticides, herbicides, and solvents. Exposure to paraquat or maneb/mancozeb was associated with about a 2-fold increase in risk. In high-quality case-control studies including an appreciable number of cases (>200), heterogeneity remained significantly high (>40%) only for insecticides, organochlorines, organophosphates, and farming; also, the risk associated with rural living was found to be significant.
  
  
  CONCLUSIONS
  The literature supports the hypothesis that exposure to pesticides or solvents is a risk factor for PD. Further prospective and high-quality case-control studies are required to substantiate a cause-effect relationship. The studies should also focus on specific chemical agents.
authors.affiliation: Parkinson Institute, Istituti Clinici di Perfezionamento, Milan, Italy.
authors.forename: Gianni
authors.initials: G
authors.lastname: Pezzoli
authors.forename: Emanuele
authors.initials: E
authors.lastname: Cereda
mesh_terms: D016022:Case-Control Studies; D015331:Cohort Studies; D004781:Environmental Exposure / Q000009:adverse effects*; D006540:Herbicides / Q000009:adverse effects*; D006801:Humans; D010300:Parkinson Disease / Q000175:diagnosis / Q000209:etiology*; D010575:Pesticides / Q000009:adverse effects*; D011446:Prospective Studies; D057566:Self Report; D012997:Solvents / Q000009:adverse effects*
chemical_list: D006540:Herbicides; D010575:Pesticides; D012997:Solvents