But the five-year, $5 million study doesn’t fully answer question of whether the needle-shaped fibers in taconite dust are linked to mesothelioma.
MOUNTAIN IRON, Minn. – The more time taconite workers spent on the job, the more likely they were to develop a rare and deadly lung cancer, researchers revealed Friday as they delivered the findings of a long-awaited study at a packed community meeting in this tiny town on Minnesota’s Iron Range.
But the five-year, $5 million Taconite Workers Health Study didn’t offer a complete answer to the question that has been confronting miners and their families for decades — whether their exposure to taconite dust bears some blame. The researchers said that at this point their research shows a possible link, but not a certain one.
The state-funded University of Minnesota research was designed to address concerns on the Iron Range about debilitating and deadly lung diseases wrought by long, needle-like fibers in commercial asbestos and dust from taconite ore.
Speaking to about 100 miners, family members and others at the community center here, researchers said that for each year a worker spent in the taconite industry, his risk of being stricken by mesothelioma, a deadly cancer of the lung lining known to be caused only by asbestos, increased by 3 percent.
“Working longer times in the taconite industry does have risk associated with it — that is an important finding,” said Dr. Jeffrey Mandel, a physician and epidemiologist from the university who led the study.
Craig Pagel, executive director of the Minnesota Iron Ore Association, attended the meeting. He said industry officials would have to study the results in more depth before commenting on their significance.
“We are happy the data is out, and will be reviewing it,” he said. “And we are looking forward to seeing the final outcome of the studies.”
Cliffs Natural Resources, one of the taconite operators on the Range, said in a statement that the company has provided employee data and records for the study, but also wants to review the findings before commenting.
Questions about the relationship between taconite and lung disease have dogged the Iron Range for years. Controversy about asbestos erupted on the Iron Range 40 years ago when needle-like fibers were discovered in Lake Superior and traced to the dumping of taconite waste rock.
Fears about the disease reignited in 2007 when the Star Tribune revealed that the state Health Department under former Gov. Tim Pawlenty suppressed research findings for a year about 35 additional miner deaths from mesothelioma. It provoked a public outcry, the resignation of the state health commissioner and legislation that funded the extensive study presented Friday.
Most workers and retirees, who braved a snowstorm to attend Friday’s meeting, expressed gratitude for the new information and gave generally positive reviews to the technical presentation.
“We’re making progress,” said Dave Trach, who spent 38 years at the now-closed LTV operation near Hoyt Lakes and now serves on the executive board of the Steelworkers Organization of Active Retirees. “We’ve got people looking at it in a scientific way.”
Bob Pulkinen, another retired LTV worker who now suffers from asbestosis that he attributes to 36 years in the mines, said the research is needed to assure the next generation of mine workers that conditions are safe. “This is beneficial,” he said.
But for some, the answers for which they’d long been waiting came up short.
Sam Ricker, who spent 35 years as a machinist at what is now United Taconite, had hoped to find more clarity on what risk the fibers in the ore pose to workers.
“I expected more,” Ricker said.
Researchers found that 80 miners, all men, have died of the rare cancer, a rate nearly three times that in the rest of the state’s population. Commercial asbestos was once used widely in the taconite industry for insulation and other purposes and remains a prime suspect in the Iron Range cases.
University researchers, at least in this phase of the study, didn’t try to parcel out blame between commercial asbestos products and fibers from the ore itself. Mandel said researchers believe “there is something about working in the industry that is playing into this.” They plan to conduct more analysis of fiber data to get clearer answers.
Other experts on mesothelioma and mining said that it is extremely difficult to reconstruct exposures that occur over a lifetime.
“It’s not that taconite is not indictable,’’ said Dr. Michael Harbut, an expert on mining-related mesothelioma at Wayne State University in Detroit. “But it’s so hard to separate out the exposures.”
Nonetheless, the research is an important advance, said Christopher Weis, an expert on asbestos and mesothelioma at the National Institutes of Health.
“Dr. Mandel and his team have now confirmed what many have suspected for decades,” he said. “There is a clear relationship between exposure to taconite dust and mesothelioma in humans.”
Moreover, Weis said their future research could play an important part in exposing the role that other, shorter mineral fibers play in lung diseases, which might show that the risks for mesothelioma come from more than just the long fibers typical of asbestos.
“We’ve long suspected that those fragments contribute significantly to lung disease,” he said.
Risk limited to workers
Other findings in the multipart study suggested that spouses of workers and others in the community don’t face an increased risk of diseases. Researchers also said that occupational exposure to dust in taconite operations is generally within safe limits. Air tests for fibers in Iron Range communities found no excessive dust, and no sign of asbestos particles at all.
One major part of the study reconstructed historic exposure to airborne mineral fibers back to the 1960s. This was necessary because mesothelioma can take 30 or 40 years to develop.
From that, researchers concluded that victims of the rare cancer were more likely to have had higher exposures to longer, needle-like fibers including asbestos and non-asbestos rock fragments such as those produced by crushing ore. But researchers reached no precise conclusions about it.
“It’s not a huge risk, but it is a risk potentially associated with this exposure,” said Bruce Alexander, a professor of environmental health at the university.
The study also found that asbestos-related cancers struck all across the Iron Range, and were not concentrated in some parts as some miners have suspected.
Mandel said additional findings will be presented in one or two future meetings. A report on the current phase is expected to be published in days, with a final report later this year. Researchers also are planning continued research, and have applied for more than $2 million in federal and foundation grants.
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