Narrowing the Cause of Mesothelioma in MN Taconite Miners

By March 1, 2017
Associate Professor Jeffrey Mandel

Associate Professor Jeffrey Mandel

A 2014 study from the School of Public Health showed that workers in the state’s taconite mining industry face increased risk for developing mesothelioma, a rare cancer of the lung’s lining. The cancer develops from the inhalation of fibers that irritate the lining of the lungs, and is commonly caused by breathing in asbestos dust fibers. Researchers aren’t sure which specific fiber is responsible for the cancer in Minnesota’s miners and where they come from. Now, a new study from the school suggests the disease is not likely caused by non-asbestiform elongate mineral particles (EMP), a fiber produced by Minnesota’s taconite mining.

The new study was published in the American Journal of Industrial Medicine.

“Unlike other cancer-causing particles, like asbestos, the Minnesota mining fiber is the non-asbestiform, which means it doesn’t flake off and get into the air easily,” says lead author and Associate Professor Jeffrey Mandel. “But there’s concern that when taconite is mined, they crush it and some of these non-asbestiform EMP fibers could still be released.”

There are different varieties of EMP fibers. Non-asbestiform versions similar to Minnesota’s are also produced by talc and gold mining. Given the similarities, Mandel and his team reviewed 12 mortality studies from those industries to see if they also showed cases of mesothelioma.

“What we found is that the occurrence of mesotheliomas in those other settings is extremely rare,” says Mandel. “It suggests that the non-asbestiform fiber from the ore that’s mined in Minnesota does not appear to have the same risks as asbestos fibers.”

The results mean the hunt is still on for the fiber causing the mesothelioma cases in Minnesota’s taconite miners. Researchers in the school are now involved in an electron microscope study of samples of fibers found in Minnesota’s mining plants to see if anything about their form and appearance yields any clues. They are also repeating the 2014 study with a larger number of mesothelioma cases and the new electron microscopy information.