title: Persistent organochlorine pesticides in serum and risk of Parkinson disease.
abstract: BACKGROUND
  Pesticides have been implicated as likely environmental risk factors for Parkinson disease (PD), but assessment of past exposure to pesticides can be difficult. No prior studies of pesticide exposure and PD used biomarkers of exposure collected before the onset of PD. Our investigation examined the association between prospective serum biomarkers of organochlorine pesticides and PD.
  
  
  METHODS
  We conducted a nested case-control study within the Finnish Mobile Clinic Health Examination Survey, with serum samples collected during 1968-1972, and analyzed in 2005-2007 for organochlorine pesticides. Incident PD cases were identified through the Social Insurance Institution's nationwide registry and were confirmed by review of medical records (n = 101). Controls (n = 349) were matched for age, sex, municipality, and vital status. Adjusted odds ratios (ORs) of PD were estimated using logistic regression.
  
  
  RESULTS
  Little association emerged with a summary score of the 5 organochlorine pesticides found at high levels, and only increasing dieldrin concentrations trended toward a higher risk of PD (OR per interquartile range [IQR] 1.28, 95% confidence interval [CI] 0.97-1.69, p = 0.08). Because of possible strong confounding by cigarette smoking among smokers, we ran additional analyses restricted to never smokers (n = 68 cases, 183 controls). In these analyses, increasing dieldrin concentrations were associated with increased odds of PD (OR per IQR 1.95, 95% CI 1.26-3.02, p = 0.003). None of the other organochlorine pesticides were associated with PD in these analyses.
  
  
  CONCLUSIONS
  These results provide some support for an increased risk of Parkinson disease with exposure to dieldrin, but chance or exposure correlation with other less persistent pesticides could contribute to our findings.
authors.affiliation: Harvard School of Public Health, Department of Environmental Health, Landmark Center, Boston, MA 02215, USA. mweissko@hsph.harvard.edu
authors.forename: M G
authors.initials: MG
authors.lastname: Weisskopf
authors.forename: P
authors.initials: P
authors.lastname: Knekt
authors.forename: E J
authors.initials: EJ
authors.lastname: O'Reilly
authors.forename: J
authors.initials: J
authors.lastname: Lyytinen
authors.forename: A
authors.initials: A
authors.lastname: Reunanen
authors.forename: F
authors.initials: F
authors.lastname: Laden
authors.forename: L
authors.initials: L
authors.lastname: Altshul
authors.forename: A
authors.initials: A
authors.lastname: Ascherio
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D004026:Dieldrin / Q000097:blood; D004781:Environmental Exposure; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D006843:Hydrocarbons, Chlorinated / Q000097:blood*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010300:Parkinson Disease / Q000097:blood* / Q000453:epidemiology*; D010575:Pesticides / Q000097:blood*; D012042:Registries; D012307:Risk Factors; D012907:Smoking; D055815:Young Adult
chemical_list: D006843:Hydrocarbons, Chlorinated; D010575:Pesticides; D004026:Dieldrin