Neurologist: Manganese Exposure Limits Not Adequate

Manganese is one of the materials processed at a refinery in Worsley, Australia. (Courtesy of South32)Manganese is one of the materials processed at a refinery in Worsley, Australia. (Courtesy of South32)

Limits set by the Environmental Protection Agency to protect the public from exposure to manganese might be too lenient, says one of the world’s leading experts on the health effects of manganese. 

Neurologist Brad Racette has devoted his career to studying the impact of exposure to manganese. Primarily used in steelmaking, manganese has been shown to negatively impact the nervous system at high concentrations. 

Over the past decade, Racette, who heads the Neurology Department at Washington University’s School of Medicine in St. Louis, tracked the health of almost 400 welders in the Midwest who were exposed to fumes containing manganese. In a study published in December in the journal Neurology, Racette revealed that even though welders’ exposure was below regulatory limits for manganese, they were more likely to develop Parkinson’s-like symptoms associated with chronic manganese exposure.

 “This study suggests that we need more stringent workplace monitoring of manganese exposure, greater use of protective equipment and monitoring and a systematic assessment of workers to prevent this disabling disease,” Racette said in a news release. 


More: Read our full series on manganese on Chicago’s Southeast Side


Until the past five or 10 years, Racette said manganese research had focused on exposure in occupational settings, such as the workplaces of the welders he studied. But more recently, Racette and some other researchers have turned their attention to environmental exposure. Their aim is to better understand the impact of manganese on people who live near industrial sites that handle the material.

One such site is a heavily industrialized area on Chicago’s Southeast Side, where residents recently learned about potentially harmful levels of manganese detected nearby. Racette has not studied this location, but said it is likely that current regulatory thresholds for environmental manganese exposure are not stringent enough. 

“I think that there’s a strong argument that [limits] may not be adequately protecting people,” Racette told Chicago Tonight.

The EPA uses a measurement called reference concentrations to estimate the amount of a pollutant an individual could be exposed to over a lifetime without experiencing adverse health effects, according to EPA documents.

For manganese, the agency lists a reference concentration of 0.05 milligrams per cubic liter.

Brad Racette (Washington University)Brad Racette (Washington University) In 2008, the Ohio EPA found concentrations of airborne manganese up to 34 times higher than the EPA’s reference concentration at a storage facility run by the same company linked to potentially harmful manganese exposure in Chicago.

The company, S.H. Bell. Co., installed air monitors at its Chicago facility Feb. 28, ending a nearly three-year battle with the EPA. The agency said one of the monitors will be used to analyze manganese levels to evaluate whether the facility is threatening public health.

Racette said he expects to know more about dangers associated with manganese exposure soon. He’s currently in the second year of a five-year study evaluating motor and cognitive effects on roughly 1,000 adults living near one of the world’s largest manganese smelters, in Meyerton, South Africa.

The study will be the largest to examine environmental manganese exposure in adults, he said.

“One of the things I’ve discovered over the years is that there’s a lot of misunderstanding about what manganese is because people have largely referred to studies that are 40 or 50 years old to try to interpret what happens in modern settings,” said Racette, who said he has published more studies than anyone in the world on the clinical aspects of manganese exposure. 

Racette said because previous research has focused mostly on occupational manganese exposure, there has been an assumption that environmental exposure is safe by comparison.

But his latest study found that despite a body of research, the occupational exposure limits set by regulators were too lenient.

“If that’s the case, then maybe these environmental thresholds need to be studied as well,” he said. “I think what’s important is we need to understand what a safe level of exposure to manganese is. We’re trying to answer that exact question.”

Follow Alex Ruppenthal on Twitter: @arupp


Related stories:

Alderwoman: More Info Needed to Evaluate Chicago Manganese Ban

March 7: Several advocacy groups are calling on Chicago to ban storage of materials containing manganese in residential areas following a 2016 study that revealed potentially harmful levels of manganese dust on the city’s Southeast Side.


Chicago Rejects Company’s Plan to Control Manganese Dust

March 6: A company on Chicago’s Southeast Side has 30 days to submit a revised plan to control the release of manganese dust, according to the city’s Department of Public Health.


Chicago Facility Linked to Manganese Meets Air-Monitor Deadline

March 1: A company under pressure from the EPA over potentially harmful emissions of manganese dust has met the agency’s March 1 deadline for installing air monitors at its Chicago facility.


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