title: A prospective analysis of airborne metal exposures and risk of Parkinson disease in the nurses' health study cohort.
abstract: BACKGROUND
  Exposure to metals has been implicated in the pathogenesis of Parkinson disease (PD).
  
  
  OBJECTIVE
  We sought to examine in a large prospective study of female nurses whether exposure to airborne metals was associated with risk of PD.
  
  
  METHODS
  We linked the U.S. Environmental Protection Agency (EPA)'s Air Toxics tract-level data with the Nurses' Health Study, a prospective cohort of female nurses. Over the course of 18 years of follow-up from 1990 through 2008, we identified 425 incident cases of PD. We examined the association of risk of PD with the following metals that were part of the first U.S. EPA collections in 1990, 1996, and 1999: arsenic, antimony, cadmium, chromium, lead, manganese, mercury, and nickel. To estimate hazard ratios (HRs) and 95% CIs, we used the Cox proportional hazards model, adjusting for age, smoking, and population density.
  
  
  RESULTS
  In adjusted models, the HR for the highest compared with the lowest quartile of each metal ranged from 0.78 (95% CI: 0.59, 1.04) for chromium to 1.33 (95% CI: 0.98, 1.79) for mercury.
  
  
  CONCLUSIONS
  Overall, we found limited evidence for the association between adulthood ambient exposure to metals and risk of PD. The results for mercury need to be confirmed in future studies.
authors.affiliation: Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, USA.
authors.forename: Natalia
authors.initials: N
authors.lastname: Palacios
authors.forename: Kathryn
authors.initials: K
authors.lastname: Fitzgerald
authors.forename: Andrea L
authors.initials: AL
authors.lastname: Roberts
authors.forename: Jaime E
authors.initials: JE
authors.lastname: Hart
authors.forename: Marc G
authors.initials: MG
authors.lastname: Weisskopf
authors.forename: Michael A
authors.initials: MA
authors.lastname: Schwarzschild
authors.forename: Alberto
authors.initials: A
authors.lastname: Ascherio
authors.forename: Francine
authors.initials: F
authors.lastname: Laden
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000633:toxicity*; D000397:Air Pollution / Q000706:statistics & numerical data*; D001151:Arsenic / Q000633:toxicity; D015331:Cohort Studies; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D019216:Metals, Heavy / Q000633:toxicity*; D008875:Middle Aged; D010300:Parkinson Disease / Q000453:epidemiology*; D011446:Prospective Studies; D014481:United States
chemical_list: D000393:Air Pollutants; D019216:Metals, Heavy; D001151:Arsenic