Manganese exposure: How much is too much?

A manganese smelting plant in South Africa belches out white smoke.
Photo by Brad Racette. A manganese smelting plant in South Africa belches out white smoke.

Neurologist Brad Racette, MD, has teamed up with a South African public-health expert to study the effects of manganese exposure on human health.

Washington University School of Medicine in St. Louis is leading a study to determine whether people develop neurological damage from manganese at levels currently deemed to be safe. The National Institute of Environmental Health Sciences of the National Institutes of Health (NIH) is funding the $3.7 million study.

Federal environmental and public health agencies have established levels at which manganese exposure becomes a danger to human health. But some scientists suspect the levels should be lowered.

According to Brad A. Racette, MD, large parts of the United States Midwest have high levels of manganese exposure, particularly in the Rust Belt. So does South Africa, where 80% of the world’s manganese is found.

One of the largest manganese smelters in the world is located about 30 miles south of Johannesburg. Manganese from the smelter releases into the air and settles into soil and water, creating a health hazard to surrounding communities. In the United States, a similar process has contaminated the land around iron and steel factories.

Racette has teamed up with Gill Nelson, PhD, a professor at the University of the Witwatersrand School of Public Health in South Africa. They are studying a community near the smelter to determine if its residents have more difficulty with certain neurological  functions than those living farther away.

The study will continue for another three years. The smelter continues to release manganese, but even if the plant were to shut down, the effects of previous exposure would remain. Says Racette, “This is a problem that’s not going away.”

Learn more on the School of Medicine website.