Can Exposure to Airborne Metals Increase Parkinson Disease Risk?

Residential exposure to airborne heavy metals may increase the risk of developing Parkinson disease (PD), according to study results presented at the 2024 American Academy of Neurology (AAN) annual meeting, held from April 13 to 18, 2024, in Denver, Colorado.

Exposure to heavy metals through inhalation, ingestion, or skin contact has raised concern for the chronic and potentially irreversible side effect of neurotoxicity. Oxidative stress due to heavy metal exposure can contribute to progressive neurodegeneration within the central nervous system.

Researchers at Barrow Neurological Institute and the Washington University in St. Louis conducted a population-based, case-control study in which they analyzed the relationship between environmental exposure to 11 different airborne heavy metals and the risk of developing PD.

The researchers collected estimates for air concentrations of antimony, arsenic, beryllium, cadmium, chromium, cobalt, lead, manganese, mercury, nickel, and selenium located at a specific zip code for the 2 years prior to 2009. This data was obtained from all sources modeled by the Environmental Protection Agency (EPA).

Next, the researchers analyzed Medicare data from this same zip code. They compared the 51,991 residents diagnosed with incident PD in 2009 to the 13,177,274 residents who did not develop PD during this period.

Adjusting for confounding variables, such as age, sex, race, and smoking, the researchers calculated the relative risk (RR) for PD associated with each of the 11 metals. Only manganese (RR, 1.007; 95% CI, 1.001-1.012) remained significantly associated with PD risk across all sensitivity analyses; however, nickel (RR, 1.006; 95% CI, 0.997-1.014) and beryllium (RR, 1.008; 95% CI, 0.999-1.017) demonstrated potential associations with PD risk of similar magnitude.

Manganese increased the risk for PD across various sources of exposure, including major point sources of exposure (RR, 1.006; 95% CI, 1.001-1.012), non-point sources of exposure within the area (RR, 1.009; 95% CI, 1.001-1.016), and mobile sources of exposure on the road (RR, 1.011; 95% CI, 1.001-1.022).

“Residential exposure to airborne manganese, and possibly beryllium and nickel, might increase risk of PD,” the researchers concluded.