Health Concerns Associated With Mining Activity In Northeastern Minnesota

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The Minnesota Department of Health (MDH) is proposing two new health studies addressing potential health concerns in northeastern Minnesota.

One of the studies would focus on the health of mine workers in the region. The other would assess the potential health impact of specific types of airborne mineral fragments generated by ore processing activity on the east end of Minnesota's iron range. The assessment would then be used to set regulatory exposure limits for those materials.

MDH proposed the new mine worker study after receiving reports of additional mesothelioma cases in a group of mine workers who had been the subject of an earlier study, completed in 2003.

Mesothelioma is a rare, fatal form of cancer seen almost exclusively in people who have been exposed to asbestos. When the earlier study was conducted, MDH had identified 17 diagnosed cases of mesothelioma in a group of 72,000 people who worked in Minnesota's iron mining industry between the 1930s and 1982.

MDH has since identified 35 additional cases of mesothelioma in that group, raising the total number of cases to 52. MDH officials say it's not surprising to see additional reports of the illness among the miners in the 2003 study, since it can take as long as 40 or 50 years to develop mesothelioma following exposure to asbestos.

The earlier study concluded that the 17 original mesothelioma cases were most likely caused by exposure to forms of asbestos that are found in a variety of industrial settings, and are not unique to the mining industry.

"The mesothelioma issue has been with us for a long time," said Minnesota Health Commissioner Dianne Mandernach. "There are important, unresolved questions that we need to address, and we believe this new study will help us provide some of the answers.

"Although the new mesothelioma cases are a major health concern in their own right, they're just part of a larger picture," she added. "Since mesothelioma is usually an indicator of asbestos exposure, the workers we studied may also be at risk for other asbestos-related illnesses like lung cancer and asbestosis. Those diseases potentially affect much larger numbers of people."

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The new study will focus on the same group of workers, comparing workers who developed mesothelioma with those who did not, in an effort to determine what aspects of their jobs might have placed them at risk.

The second MDH study would assess the health risks associated with airborne mineral fragments from ore mined in some areas on the east end of the range. The risk assessment will assist in setting airborne exposure limits designed to protect the general public from any potential health effects associated with those materials.

The new regulatory exposure limits will be established using a new methodology, to be developed as part of the study. In developing the new methodology, MDH will use data from animal studies that had previously been collected by the U.S. Environmental Protection Agency (EPA).

This new methodology may also be useful in setting site-specific exposure limits at other locations in the state where ore could contain mineral fragments posing a potential health concern.

MDH plans to seek federal funding for the mesothelioma study from the National Institute for Occupational Safety and Health (NIOSH) and other sources. Once funding is obtained, the study is expected to take three years to complete, at a cost ranging from $750,000 to $1 million.

The mineral fragment study is expected to take about a year once the animal study data becomes available from EPA, at an estimated cost of $250,000.

The proposed study of mesothelioma in mine workers will expand and build on the 2003 study, which was the first to ever conclusively document the occurrence of mesothelioma in Minnesota mine workers.

The earlier study looked at the work histories of the 17 miners with mesothelioma, in an effort to determine what might have exposed them to asbestos. While MDH investigators were conservative about drawing conclusions from the 2003 study, they suggested that the 17 original mesothelioma cases were most likely caused by exposure to "commercial" asbestos.

Commercial asbestos includes a variety of products and materials that have commonly been used in industrial settings, but are not unique to mining operations

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