On Jan. 17, the Santa Cruz County Advisory Panel for the South32 Hermosa Project hosted Dr. Brad Racette, a leading neurologist in the field of manganese toxicity and Chair of Neurology at Barrow Neurological Institute in Phoenix, an international center for neurologic disease treatment and research.
At the meeting, Dr. Racette, whose experience with manganese toxicity spans over 20 years, discussed the human and environmental impacts of exposure to manganese.
South32 plans to mine battery grade manganese underground for the electric vehicle supply chain at the Clark Deposit over the next 60 years in the Patagonia Mountains. Information circulating via email and Facebook groups (videos of manganese mines in Australia and South Africa, data on health concerns, etc.) has elevated public awareness and concern about the dangers of manganese exposure.
Recent discussions of the mine’s intent to build a manganese processing plant, preferably somewhere in the western part of the County, have motivated many people in Rio Rico and surrounding communities to get involved. The topic has been front and center during the public comment period of several County Board and ADEQ meetings.
The National Institute for Occupational Safety and Health states that overexposure to manganese can lead to symptoms like Parkinson’s disease and may include trembling, stiffness, slow motor movement and potentially severe depression, anxiety, and hostility. The level of exposure depends upon the dose, duration, and the way the material is being handled.
Dr. Racette said he has examined over 5,000 people exposed to manganese around the world. One study involved over 1,000 welders in the U.S. who were exposed to manganese because it is used to strengthen steel. Many of the welders entered the workforce right out of high school. By the time they were in their 40s, they were showing Parkinson’s symptoms rated at level 10 (16 is the threshold rating for Parkinson’s Disease). By the time these welders retire, they will be well above the rating for Parkinson’s. “The more manganese exposure, the more progression, and the levels of disability can exceed what you see in people with Parkinson’s,” Racette said.
Racette has also received and studied over 90 brains from people overexposed to manganese and was able to verify accumulation of the toxin in the brain, lower brain cell density and signs of inflammation.
Racette conducted environmental work in South Africa in a community about 30 miles southeast of Johannesburg in an industrial valley. The community lived in low-cost government housing at the fence line of a manganese smelter. He said people could not even open their windows due to the heavy concentrations of black dust. He and his team spent four years modeling exposure levels and conducted motor impact assessments and cognitive studies, including 60 brain MRI’s.
He found that the people had cognitive impairments, some anxiety, and evidence of manganese accumulation in the brain, similar to that seen in welders. “Once you have a certain amount of exposure, the neurological damage doesn’t really reverse. Even without ongoing exposure, the symptoms actually may continue to progress. This is a problem that is not going away,” Racette said.
Racette said that the highest level of manganese exposure is found in welding, the steel industry, mining, and smelting. To the core of the problem, Racette said, “The manganese research community feels the established exposure limits are too high,” which begets the question, how low do we go?
Exposure limits for manganese are very confusing. Some limits are set by regulations and others are advisory guidelines. The Office of Safety and Health Administration (OSHA) sets enforceable permissible exposure limits (PEL) to protect workers against health effects of exposure to hazardous substances, including limits on the airborne concentrations. The OSHA PEL for manganese is 5 milligrams per cubic meter. Racette described the OSHA limits as ridiculous, “just way too high.”
The American Conference of Governmental Industrial Hygienists (ACGIH), a non-profit established in 1946, recommends a threshold exposure level of 0.02 milligrams per cubic meter as a respirable fraction averaged over an 8-hour work shift. The OSHA PEL is 250 times higher than the ACGIH recommendation.
Racette believes the standard should even be lower than the ACGIH levels. The Agency for Toxic Substances and Disease Registry (ATSDR), a federal public health agency under the Dept. of Health and Human Services, recommends a standard for respirable manganese dust at 0.0003 milligrams per cubic meter.
Pat Risner, President of the Hermosa Project said that the manganese mining in Patagonia will be completely different in terms of how the mining, transport, onload/offload, and processing of manganese is managed compared to other mines established decades ago. “We can take the lessons that everybody’s had all over the world and apply those here,” he said. Risner said his concept is that from time the ore is mined to the time it is loaded and shipped, it will not be exposed to the environment.
In response to a question posed at the meeting, Racette said, “From what I’ve heard [about the Hermosa project], there are a lot of good faith efforts being made to run a mine unlike what I have seen in the past.”
In an interview with the PRT after the meeting, when Racette was asked if he would consider a partnership with South32 to better inform an exposure level for manganese, he replied, “Absolutely! Our lab has been involved in occupational exposures for the last 20 years. It’s serendipitous.”
When the PRT then asked Risner if South32 would consider working with Racette, he replied, “The research he has done is good input for what we are doing. I have said all along that we will seek external expertise. We are going to do baseline assessments and health surveillance and environmental studies so there is an opportunity to get input from research like what he has done to make sure we are doing the right things in those programs.”