Taconite poses health risk to miners

Published 9:15 am Tuesday, December 2, 2014

MINNEAPOLIS — A final report to the Legislature on a six-year, $4.9 million University of Minnesota study says the state’s taconite workers face higher risks from a rare form of lung cancer called mesothelioma the longer they’ve worked in the industry or if they’ve had above-average exposures to certain kinds of dust.

The study assessed the risks to taconite workers from exposure to tiny, needle-like fibers called elongate mineral particles, or EMPs. Mesothelioma, a usually fatal cancer of the lung lining, is generally caused by exposure to airborne asbestos fibers.

Lawmakers commissioned the study after a spike in the cancer was found on the Iron Range in 2006. Researchers planned to present the final report at a community meeting in Hibbing on Monday.

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Many of the key conclusions from the study were in a preliminary report in April 2013, including that taconite workers had triple the death rate from mesothelioma than ordinary Minnesota residents. Taconite workers also died at higher rates from more common kinds of lung cancer and heart disease at higher rates, they found.

The final report adds a closer look at the role of EMP exposure levels in taconite workers’ risks of mesothelioma as well as the role these exposures might play in other diseases, principal investigator Jeffrey Mandel said.

For example, the study found the number of years people worked in the industry was linked with their mesothelioma risk, but not their risk of other lung cancers. It also found workers with above-average EMP exposures were nearly twice as likely to get mesothelioma as workers with below-average exposures. But it found no apparent links between EMPs with rates of other lung cancers among these workers.

The study also says these workers face an elevated risk of dust-related noncancerous scarring of the lung and lung lining.

Researchers analyzed 57 mesothelioma cases found among taconite workers through 2010. They were unable to determine to what extent the increased mesothelioma risk came from mining dust or from exposure to commercial asbestos that used to be common in taconite plants, said John Finnegan, dean of the university’s School of Public Health.

The final report makes several recommendations, including more data collection, steps to reduce controllable risk factors for cardiovascular disease and reducing exposure to EMPs and other kinds of dust, including more use of respirators.

“Given the known hazards in mining, the process of avoiding exposures generated in the mining and processing of taconite ore is critical,” the report said.

Mesothelioma is rare, even among taconite workers, the report said. An average person who lives to be 80 has a 0.144 chance of developing the disease, or about 1.4 cases per 1,000 individuals. A person who worked in the taconite industry for 30 years has an average chance of 0.333 percent of getting mesothelioma, or about 3.3 cases per 1,000 miners who live to be 80.

“Under most normal operating conditions the plants are safe. But it is an inherently dusty industry, and it has risks,” Mandel said.