A Prospective Analysis of Airborne Metal Exposures and Risk of Parkinson Disease in the Nurses Health Study Cohort

Environ Health Perspect. 2014 Jun 6. [Epub ahead of print]

Palacios N, Fitzgerald K, Roberts AL, Hart JE, Weisskopf MG, Schwarzschild MA, Ascherio A, Laden F.

Abstract

BACKGROUND:

Exposure to metals has been implicated in the pathogenesis of Parkinson disease (PD).

OBJECTIVES:

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 Environmental Protection Agency'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 to 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 EPA collections in 1990, 1996, and 1999: arsenic, antimony, cadmium, chromium, lead, manganese, mercury and nickel, as well as total (sum) metal exposure. To estimate Hazard Ratios (HRs) and 95% confidence intervals (CI), 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.