Links between mesothelioma, taconite mining hard to find

May 31st, 2012 · 10:12 pm @   - 

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A comprehensive study on why so many Iron Rangers are dying of a rare lung disease is entering its final data-crunching stages with some results expected later this year.

But in an update provided Thursday, key researchers confided that they may never find a link between a high rate of fatal mesothelioma and the taconite iron ore industry — that the high rate of mesothelioma deaths among Rangers may have been caused by exposure long ago and far away.

“That’s one of the possibilities. It could be we don’t see any relationship to the workplace,” said Jeff Mandel, an associate professor at the University of Minnesota’s School of Public Health and the lead researcher in the study.

But researchers in the nearly $5 million Minnesota Taconite Workers Health Study quickly added that they haven’t reached that conclusion yet and are still working to see where and how Rangers may have been exposed to asbestos or asbestos-like fibers that are the only known cause of always-fatal mesothelioma.

On Thursday researchers revealed that the study already has confirmed a 300 percent higher rate of mesothelioma on the Iron Range than the general population in Minnesota.

Thursday’s update, the first since October, also reported that Rangers have about 20 percent more lung cancer and 11 percent more heart disease than the general population.

Yet while lung cancer can be caused by smoking and heart disease from bad eating habits and obesity, mesothelioma can come only from exposure to certain kinds of airborne fibers. Researchers said they simply aren’t finding many, if any of the traditional asbestos size mineral fibers in their study. So now they are focusing on shorter fibers. Once called “asbestos-like fibers,” researchers are now calling them “elongated mineral particles” because they are not truly asbestos.

Some Rangers have speculated that the lung disease killing their cohorts comes from the minerals in the rock released by the process of mining low-grade iron ore and processing it into taconite pellets. Researchers continue to look at that but say it’s possible the exposure came from previous jobs, such as in the ship building industry or onboard asbestos-laden Navy ships, or handling asbestos molds or insulation while working in taconite plants.

Meanwhile a health screening of current and retired taconite workers found that 17 percent had reduced lung capacity and about the same had abnormalities on tissue around the lung. It’s not clear, however, if those problems are from smoking, dust exposure or other issues.

At least 82 Iron Rangers have died in recent years from mesothelioma, which often doesn’t appear until 30-40 years after initial exposure to asbestos fibers.

It’s estimated about 80,000 workers have been involved in mining since the first operations began in Minnesota in the late 1800s. Researchers are focusing on the roughly 46,000 people born since 1920 who worked in the production of taconite, which has been mined and processed in Minnesota since the 1950s.

The health study, headed by the University of Minnesota’s School of Public Health and funded by the 2008 Minnesota Legislature, has five distinct parts:

r An occupational exposures assessment to determine how and where the asbestos or shorter particles came from.

r A mortality study to determine the cause of death for thousands of deceased taconite workers.

r A cancer incidence study to see whether lung cancer rates are higher on the Iron Range.

r An environmental study of current airborne particulates to check for asbestos levels in taconite plants and in local cities.

r And a respiratory health study of living taconite workers and their spouses.

All of the field work has been completed and now scientists are crunching their numbers. All of the data analysis will be peer reviewed before it’s released.

Bob Brown, safety chairman for United Steelworkers of America Local 2750 at Hibbing Taconite, who serves on the health study’s advisory committee, said Thursday’s update was good but steelworkers are still awaiting the results with trepidation.

“It seems like they are doing a very thorough job. I think people are satisfied that they are at least taking this serious this time,” said Brown, 56. “But people are worried. They want to know if they are going to have some golden years after they retire or if they are just going to get sick. I’ve got 24 years in at HibTac and 35 years in the mining game. … I’m concerned where this (lung disease) is coming from.”

Brown said he was encouraged to hear that the study also is looking at the relatively high exposure to silica in taconite operations as a possible health concern.

Results from each of the five study parts will be made public after they are completed, with some later this year and a final, overall report is expected in 2013.

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