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Researchers look for links between taconite and mesothelioma

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Mining truck, Hibbing Taconite
A 240 ton truck carries taconite rock to the crusher building at Hibbing Taconite.
MPR Photo/Bob Kelleher

Mining, and processing taconite, are dirty, dusty jobs.  It's hard to avoid breathing the dust from the taconite, which is crushed to the consistency of talcum powder.  And asbestos is still used in some older furnaces and other equipment.

Jim Kelly retired three years ago from the Northshore mine at Silver Bay.  He has a spot on one lung that's probably a precursor to asbestosis.  It's a disease that causes shortness of breath and chronic coughing, and indicates an increased risk of lung cancer.

But he's not about to blame taconite for that.  He worked in other industries, and was exposed to asbestos on several jobs.  He's heard claims about the dangers of taconite for 30 years, and he doesn't think they're based on much.

Jim Kelly
Jim Kelly retired from Northshore Mining four years ago. He says he was exposed to both asbestos and taconite dust over the years, and it's impossible to say what caused the spot on his lung.
MPR Photo/Stephanie Hemphill

"It appears to me that the scientific community and the medical community cannot come to agreement on what is the specific hazard here," he says.  "At least I have to date never heard anything specific." 

Now the Minnesota Department of Health is going to try to find the answers.

It's following up on a report from 2003, about mesothelioma, a rare cancer that's a lot more common in Northeastern Minnesota than it should be.  In that study, researchers concluded the most likely cause of that high incidence was exposure to commercial asbestos.  Fourteen of the 17 miners who developed mesothelioma had been exposed to asbestos as well as to taconite dust.

Since then, another 35 miners have developed mesothelioma.  It's not surprising that the numbers are rising.  The disease typically takes 20 or 30 years to show itself.  Mary Manning is director of health promotion and chronic disease at the state Health Department.  She says the higher number of victims will allow researchers to develop a more detailed picture.

"This is number strong enough to more definitively look at commercial asbestos exposure and the taconite dust exposure," she says.

They'll do it using case controls -- comparing several miners who didn't get mesothelioma to each one who did.  They'll try to compare exposure to both taconite dust and asbestos, to see whether taconite could be the likely cause of the disease. 

Taconite fiber
This electron microscope photo shows a taconite fiber breaking up into smaller fibers in rat lung tissue. The state Health Department is conducting studies to see if taconite fibers can cause mesothelioma, a rare form of lung cancer which is usually associated with asbestos exposure.
Photo courtesy of Dr. Philip Cook, U.S. EPA

But after that long latency period, mesothelioma kills its victims quickly.  They aren't around to be interviewed about how much dust they breathed.  Dr. Alan Bender is heading up the study.  He says he has enough information to sort out who was exposed to more taconite dust.  Unions and industry are providing job descriptions.  

"And in addition we have a Ph.D dissertation that was done up there in the early 80s which actually measured dust exposure for each of these jobs, so we have quantitative measures of dust exposure," he says.   

Bender is working with researchers at the University of Minnesota to design the study, and they'll ask scientists from outside the state to review their plans.  

Mesothelioma is a very rare disease: nationwide, about 2,500 people get it each year.  Many more people, including mine workers, get lung cancer, asbestosis, silicosis, or other lung ailments.  Bender says he's thinking about including them in the study.

"This is going to major effort," Bender says, "And we're going to do what we can to answer as many questions as possible right now; that's under active discussion right now." 

But of course that would make the study more complicated and more expensive.  Bender plans to apply for federal money to pay for it.  

He says he won't be asking the state for money this time.  The earlier study had to be cut short when the legislature slashed funding during the state budget crisis of 2002.  

If the study is funded, it'll take about three years to conduct, and cost at least a million dollars.

Northshore Mining will pay for a study to be conducted by a third party and overseen by the MDH, MPCA, and Cleveland-Cliffs.