PolyMet Mine: Mercury & Health Risks

Toxic Mercury Contamination of Fish

Mercury contamination of fish is one of the biggest threats from the proposed PolyMet copper-nickel sulfide mine. Copper and nickel are bound up in sulfide ores in the Duluth Complex rock where the PolyMet mine would be located. When sulfide ore is blasted and pulverized, sulfur compounds are released to the water and the air. Sulfates (the chemical form of sulfur in contact with water) support a biochemical process that increases the release of mercury from wetlands and stream sediments and changes inorganic mercury into methylmercury.

Methylmercury bioaccumulates in the food chain, so that the level of methylmercury in fish tissue can be a million times higher than in the water. Methylmercury is toxic to wildlife and to humans.

Mercury contaminated fish sign. Photo by Joey Rozier.

The developing brains of fetuses, infants, and children are more vulnerable to methylmercury. In 2011, the Minnesota Department of Health found that 1 in 10 infants in Minnesota’s Lake Superior region are already born with unsafe levels of mercury in their blood.

The PolyMet mine, plant, and waste facilities would discharge sulfate to water and release sulfur compounds to the air. Processing of ore, wastewater seepage, and combustion of fossil fuels would also discharge mercury to the water and release mercury to the air. In addition, the PolyMet mine project would excavate, dewater, and rewet thousands of acres of wetlands.

Map of St. Louis River drainage basin, from American Rivers. Arrows (added by WaterLegacy) indicate proposed PolyMet sites and location of Fond du Lac Reservation.
The combination of all of these factors creates a “perfect storm” that would increase dangerous methylmercury contamination of fish in adjacent Minnesota wetlands and creeks, the nearby Partridge and Embarrass Rivers, and the downstream St. Louis River. The St. Louis River flows through the Fond du Lac Reservation and the City of Duluth and forms a large estuary before it drains into Lake Superior.

The rivers and many of the lakes most impacted by increased methylmercury from the proposed PolyMet mine – including the Partridge and Embarrass Rivers, the Embarrass River chain of lakes, and the St. Louis River – are already impaired due to mercury pollution.

International mercury and wetlands expert, Brian Branfireun, PhD, analyzed the impacts of the proposed PolyMet mine on downstream mercury contamination of fish. He concluded in his report on the PolyMet Final EIS:
  • Increased mercury methylation in wetlands at the NorthMet mine and tailings basin site as well as potential direct releases of mercury, sulfate and methylmercury from the project create a substantial risk of increased methylmercury in project site tributary streams, in the Partridge and Embarrass Rivers and downstream in the St. Louis River.
  • It is my opinion that the NorthMet development could create a substantial risk of ecologically significant increases in water column and fish methylmercury concentrations in downstream waters, including the St. Louis River.

Duluth child psychiatrist Margaret Saracino has explained:

In terms of methylmercury, exposure is largely due to ingestion of fish with high mercury content. Methylmercury builds in the food chain. When pregnant women eat fish high in methylmercury, the fetus is then exposed to this lipophilic heavy metal. . . Neurotoxicity is also transferred to the infant through breast milk.

Even lower level exposure can result in lower intelligence, poor concentration, poor memory, speech and language disorders, and decrease in visual spatial skills in children exposed to methylmercury in utero. Fetuses, infants, and young children are four to five times more sensitive to the adverse effects of methylmercury exposure than adults.

Failure to Conduct Health Impact Assessment

Since 2014, groups representing more than 30,000 Minnesota doctors, nurses, and other health professionals have asked Minnesota agencies to conduct a Health Impact Assessment for the PolyMet mine. The State denied both their initial request and subsequent requests made by Duluth doctors in a face-to-face meeting with state commissioners. No Health Impact Assessment was ever required or conducted for the PolyMet sulfide mine project.

In addition to the threat of toxic mercury contamination of fish, the PolyMet sulfide mine presents the following risks to human health:

  • Exposure of mine workers and community members to particulate air pollution, including cancer-causing metal particles and asbestos-like fibers.
  • Contamination of groundwater and local drinking water wells with toxic pollutants, including lead and manganese.

Read what Minnesota doctors wrote in “Sulfide Mining and Human Health” published in Minnesota Medicine in November/December of 2016:

Sulfide mining has significant potential for the release of toxic chemicals into the environment. These include a number of chemicals identified by the World Health Organization as being of major public health concern: arsenic, asbestos, cadmium, lead and mercury.

The short- and long-term effects on human health should be considered in present and future sulfide mining proposals. Both the EPA’s Health Risk Assessment (HRA) and Health Impact Assessment (HIA) can be used for this kind of evaluation.

Doctors in northern Minnesota and the statewide Minnesota Academy of Family Physicians also petitioned to change Minnesota environmental review rules to require a health risk and health impact assessment for sulfide mining. The Environmental Quality Board (EQB) held a hearing in 2016 on whether to change Minnesota rules, but no changes in rules were made.

Hear Duluth family practice doctor, Emily Onello testify at the EQB meeting:

What do Minnesota health professionals recommend?

Minnesota Public Health Association

Our mission is to create a healthier Minnesota through effective public health practice and engaged citizens. We write to request a comprehensive analysis of the health risks and public health impacts of the PolyMet sulfide mine project before any decisions are made about this controversial project.

Minnesota Medical Association

On behalf of the Minnesota Medical Association, I am writing to offer support for the request that a comprehensive analysis of the health risks and public health impacts of the PolyMet NorthMet Sulfide Mine Project be conducted. This assessment will assist the state of Minnesota in making an informed decision as to the proposed project, taking into account any potential adverse effects this type of mining may have on the health of Minnesotans.

Health Professionals and Scientists Concerned About Health Impacts of PolyMet’s Mine

We are concerned that the proposed PolyMet copper-nickel mine project could have significant adverse impacts on human health as a result of pollutants released to air, surface water and drinking water. We believe that analysis performed thus far is insufficient to assess important risks to human health and public health impacts of the pollutants that would be released from the PolyMet project.

Minnesota Academy of Family Physicians – Lake Superior Chapter

We join our colleagues in the fields of medicine, nursing, and public health as well as our state Health Department to advocate for the health of our region. A health risk assessment and a health impact assessment are the next critical steps in understanding both the short and long term consequences that PolyMet’s NorthMet project may have on our health.

Minnesota Academy of Family Physicians – Statewide Organization

The Minnesota Academy of Family Physicians (MAFP) is the largest medical specialty organization in Minnesota, representing over 3000 family physicians, family medicine residents, and medical students. On April 15, 2015, The House of Delegates unanimously approved the following resolution:
BE IT RESOLVED, that the MAFP request that a Human Health Risk Assessment be performed using the most current scientific modeling methods to evaluate the health effects of the by-­‐products of proposed mining projects, and
BE IT FURTHER RESOLVED, that the MAFP supports the subsequent completion of a Human Health Impact Assessment for mining projects so that both health professionals and the public can make informed decisions.

Minnesota Nurses Association

The PolyMet NorthMet Supplemental Draft Environmental Impact Statement (SDEIS) contains inadequate analysis of the impacts on public health from the proposal. The co-lead agencies should conduct and include a health impact assessment (HIA) in the Environmental Impact Statement to fully analyze the public health implications of PolyMet’s proposed mine.

Doctors & Nurses on the PolyMet SDEIS

We respectfully request that the PolyMet SDEIS be deemed inadequate due to unresolved concerns and insufficient assessment of health risks of the proposal. We would further request that, in revising the PolyMet SDEIS, a comprehensive Health Risk Assessment be prepared under the guidance of the Minnesota Department of Health.

Commissioner, MN Department of Health on PolyMet SDEIS

An HIA could provide recommendations to policy makers to support possible positive health outcomes and to mitigate or prevent possible negative health outcomes to improve the public’s health.