Iron Worker
Star Tribune (Minneapolis, MN) | February 20, 2003 | Burcum, Jill; Furst, Randy; Shaffer, David
Byline: Jill Burcum; Randy Furst; David Shaffer; Staff Writers
A state Health Department study has concluded that commercial asbestos exposure rather than taconite dust is the most likely explanation for the occurrence of a deadly, asbestos-related lung cancer among northeastern Minnesota iron mine workers.
The study was intended to put an end to a long-simmering controversy over the potential link between taconite dust and the region's high rate of a cancer called mesothelioma. The 81 cases diagnosed in men in the region from 1988 to 1999 was nearly double what health experts would expect.
Although taconite can contain asbestos-like minerals, researchers said that commercial asbestos - once a common fire retardant widely used in pipe insulation and boiler rooms and in welding - is likely to blame.
The report, which was authorized by the Legislature, has taken five years and is not complete. A draft of its executive summary was released only after the Star Tribune requested it under the state public records law.
Yet the study is unlikely to settle the debate over whether inhaling taconite fibers causes disease.
Prof. Ian Greaves of the University of Minnesota School of Public Health, who reviewed the draft summary, said that its dismissal of taconite's risks seemed like an opinion.
"It's not an opinion strongly substantiated by the data," said Greaves, who also cautioned that researchers didn't study enough mine workers to draw conclusions.
Even more critical was Miles Lord, the retired federal judge who for five years presided over the landmark Reserve Mining asbestos case in Duluth in the early 1970s. That case first raised concerns about taconite-related health problems.
"It is a collection of miscellaneous information and confusion which leads us nowhere," Lord said. "It seems that the Health Department is trying to reach a consensus that pleases everyone, including the mining companies, and in the process, they have pleased no one."
Dr. Alan Bender, the Health Department epidemiologist who led the study, declined to comment on it because the report is not finished. He said the full report has gone through at least 14 drafts. The department planned to present findings at an industry-sponsored symposium in March.
In the three decades since the Reserve court case, the risk of lung disease on the Iron Range has been studied extensively. Industry-funded and independent scientific studies have found no excess of lung cancer in iron-ore miners.
Yet the controversy continued, especially after a Virginia, Minn., doctor reported in 1985 that he was seeing many asbestos-related lung abnormalities in chest X-rays. An expert panel later dismissed his findings, but fears about taconite fibers remained.
In the 1990s, after a new statewide cancer-tracking system was established, the Health Department reported that men in seven northeastern Minnesota counties develop mesothelioma at a rate 70 percent or more than the state average.
Carlton County had the highest rate of mesothelioma. Many workers from a former plant in Cloquet that made asbestos ceiling tiles still lived in that county - and the Health Department had found they were at high risk for asbestos-related lung disease.
Aside from those workers, the seven-county area still had a disproportionately high rate of mesothelioma among men, suggesting some other occupational risk.
In 1998, the Legislature authorized Bender's group at the Health Department to look for a link between mining and mesothelioma or other lung diseases.
"I was just hoping to find the truth, that's all," said Rep. Tom Rukavina, DFL-Virginia, a sponsor of the measure that gave the department $1.1 million for four years to study mesothelioma and to track work-related lung diseases.
Much of the work on the mesothelioma study was completed by last year, when the Legislature cut the program.
The draft summary said that 17 mine workers from taconite operations across the Iron Range developed mesothelioma from 1988 to 1996. The study did not track mine workers who moved out of the state.
Researchers looked at what jobs the mesothelioma victims had held, relying partly on mine employment data compiled by the University of Minnesota during earlier research.
A task force of people from the mining industry, unions, Iron Range communities and local health departments advised state researchers. Some of the advisers helped Bender's team determine whether particular mining jobs exposed workers to commercial asbestos.
Of the 17 mine employees who developed mesothelioma, 11 had probably been exposed to commercial asbestos on the job, the draft summary said. Another three mine workers might have been exposed to commercial asbestos in mining or other jobs they had held.
Because 14 of the 17 mine workers had potential exposures to commercial asbestos, it, rather than taconite dust, "is the most likely explanation for the occurrence of mesothelioma in men employed," the summary said.
The summary did not say what jobs the mine workers held, except that they included maintenance, plumbing, boiler room operations and carpentry.
Based on those findings, the researchers suggested that the high rate of mesothelioma in northeastern Minnesota can be attributed largely to the health risks of commercial asbestos in two industries - the former Cloquet ceiling tile plant and iron-ore mines, the summary said.
"Iron miners as a group are at risk of developing mesothelioma and possibly other asbestos-related diseases," the summary said. Because the diseases can take decades to develop, "the risks will continue into the future even in the absence of ongoing exposures," the summary said.
Dr. Larry Sundberg, a St. Louis County epidemiologist and member of the study's task force, said the conclusions are valid and based on solid science. If the dust were causing the cancer, he said, he would have expected to see more cases in women, because the dust often blows through the communities near the mines.
Others who reviewed the summary were critical of its findings.
Dr. Henry Anderson, a mesothelioma epidemiologist and professor of occupational health and preventive medicine at the University of Wisconsin Medical School in Madison, said the study shows that commercial asbestos exposures clearly played a role in the disease, but "this does not rule out that taconite fibers might have contributed."
That view was shared by Dr. Arthur Frank, director of the Center for Environmental and Occupational Health at Drexel University in Philadelphia, who has been studying the effects of asbestos since the late 1960s.
"It is irresponsible to say the other commercial sources are the cause when there was also exposure at mining operations," Frank said. He added that "each and every exposure contributes to the risk of developing asbestos-related disease."
Dave Foster, director of District 11 of the United Steelworkers of America, which covers 13 states, said the study is a "step forward," but he also had questions after reviewing the summary.
"I'm still not completely convinced of the dust exposures not being a factor, simply because the study itself acknowledges that they were unable to fully identify mesothelioma victims, and they were unable to fully examine possible exposures because it was limited to people who still live in Minnesota," Foster said.
Joe Scholar, a retired supervisor who worked at Erie Mining Co. in Hoyt Lakes, Minn., said the report appears to be a waste of money. Scholar, who helped advise the researchers, said the Health Department refused to tell him which workers were studied and where they worked. He said he was concerned that the job titles of some workers who got mesothelioma might have incorrectly led researchers to believe they did not come in contact with taconite dust.
The Health Department said it plans to release the report early next week.
Frank Ongaro, president of the Iron Mining Association of Minnesota, which represents taconite producers and businesses that supply products and services to the mines, urged caution in judging the findings until the full report is released.
"Obviously the executive summary has been given out without the body of work that accompanies it," Ongaro said. "I think it's in everyone's best interest to make sure all the supporting documentation is provided to all of the constituency groups and that qualified individuals have a chance to review them before any final thoughts and conclusions and opinions are made by anybody."
Byron Starns, the former chief deputy attorney general who represented the state in the Reserve case, said the report raises questions about the effects of taconite dust that need further study.
In particular, he said, the Health Department needs to do a broader study of lung conditions in mine workers. Although this would take time, Starns said the Health Department has the job histories of more than 70,000 mine workers.
"The report suggests that a lot of additional work must be done to determine the health effects from exposure to taconite dust," Starns said.
- Jill Burcum is at jburcum@startribune.com.
- Randy Furst is at rfurst@startribune.com.
CHRONOLOGY
The health risk of asbestos-like fibers in taconite has been debated for three decades in Minnesota. Asbestos is known to cause chronic lung disease, including a rare form of cancer called mesothelioma. Here are some of the key events:
1973: Asbestos fibers are found in the Duluth water supply and traced to taconite tailings that Reserve Mining Co. dumped into Lake Superior.
1974: U.S. District Judge Miles Lord rules that fibers in taconite ore at Reserve's plant at Silver Bay, Minn., have some of the properties of asbestos. The company begins treating its wastewater to remove the fibers and begins testing for asbestos in the air.
1980: A Duluth doctor studies 249 men who worked at least 20 years at Reserve Mining. The study, paid for by the mining company, finds no evidence that taconite dust behaves like asbestos in the body or causes lung disease.
1983: An industry-funded study of 5,751 men who worked at Reserve Mining from 1952 to 1976 finds no increase in cancer deaths.
1985: An Iron Range doctor reports that chest X-rays of many residents and miners are abnormal, suggesting that they are at risk for asbestos-related disease. A scientific panel convened by the Minnesota Health Department reviews the X-rays and finds few abnormalities.
1985: In a study paid for by the National Institutes of Health, University of Minnesota researchers don't find an elevated rate of lung cancer in 10,403 people who worked in the iron-ore industry in St. Louis County from 1937 to 1978.
1988: An industry-funded study of 3,444 people who worked at the Erie and Minntac taconite operations in northern Minnesota from 1952 to 1976 finds that the group had a lower-than-average rate of lung cancer deaths.
1989: A Health Department study links asbestos exposure at a Cloquet ceiling tile plant to high rates of lung abnormalities in the 4,271 workers employed there from 1958 to 1974.
1992: A follow-up study of 3,444 people who worked at the Erie and Minntac operations finds that employees are not at greater risk of lung cancer or other lung diseases.
1997: The Health Department cancer-tracking system detects an unusually high rate of mesothelioma in men living in seven northeastern counties from 1988 to 1996.
1998: The Legislature authorizes $250,000 for a Health Department study of mesothelioma.
2003: The Health Department's five-year study of mesothelioma cases concludes that mine employees have been exposed to asbestos for decades, most likely while working on plumbing, in boiler rooms and in other nonmining jobs rather than from taconite dust.
- Jill Burcum and David Shaffer.
Mesothelioma in northeastern Minnesota
Mesothelioma, a rare form of cancer linked to asbestos exposure, strikes men in seven northeastern Minnesota counties at nearly twice the statewide rate, according to the Minnesota Health Department. Workers in the iron mining industry were exposed to commercial asbestos, a new study has found.
Counties with high mesothelioma rates in men
Aitkin
Carlton
Cook
Itasca
Koochiching
Lake
St. Louis
No. of cases (1988 - 99)
EXPECTED: 45
ACTUAL: 81
Mesothelioma
- These malignant tumors typically form in cell layers that line the chest and abdominal cavities. The most common tumors, pleural mesotheliomas, form in the chest lining, called the pleura.
- Inhalation of needle-like asbestos fibers is the primary cause, but the tumors take decades to appear.
- An estimated 2,000 to 3,000 new cases are diagnosed each year in the United States.
- After diagnosis, the average survival is about one year. Aggressive treatment may extend a patient's life by a year or more.
Source: American Cancer Society