Asbestos Exposure in Mining

Every asbestos product started as rock in the ground. The people who dug that rock, crushed it and bagged the fiber were among the first to breathe it, often for years. So were miners of other minerals that happen to share their deposits with asbestos, like the vermiculite at Libby, Montana, and some talc.

If you or a family member worked at an asbestos mine or mill, or at a mine where asbestos-type minerals were mixed into the ore, that work history may matter for a diagnosis of mesothelioma, lung cancer or asbestosis. Not every mine carried the same risk, and this page is honest about where the evidence is strong and where it is not.

You don't need old pay stubs or the name of every product. If you can tell us where you or your loved one worked and what the job was, we can start there.

The asbestos mines

Asbestos is a group of natural minerals. Most of what was mined in North America was chrysotile, the curly "white asbestos" of the serpentine family. Our library catalogs 559 asbestos mines worldwide, with a page for each and the documents that mention it.

Vermont: Belvidere Mountain. The quarry on Belvidere Mountain, straddling the town lines of Eden and Lowell in northern Vermont, was mined from the early 1900s through 1993. The last operator was a group of the mine's own employees, the Vermont Asbestos Group, from about 1975 until it closed. The rock yielded only 2 to 3 percent chrysotile, so enormous amounts of waste rock and tailings were left behind. In 1957 the industry's trade journal called it "the largest asbestos mine in the United States." See the Belvidere Mountain mine page, a 1978 U.S. Geological Survey study of its rocks, and a 1981 press photo of a Vermont Asbestos Group employee holding raw fiber.

California: the Coalinga district. A large chrysotile deposit straddles Fresno and San Benito counties northwest of Coalinga. The Atlas mine there, now a Superfund site, left asbestos waste piles from three open-pit mines and an abandoned mill. Johns-Manville also ran a mine and mill in the area. In a June 1965 letter, J-M's own industrial hygiene staff told the Coalinga mine that two dust stations had been over the limit for three straight years (J-M survey letters). The last asbestos mine in the United States, KCAC Inc.'s mine and mill in San Benito County, closed in 2002. See the Santa Cruz (Atlas) mine page.

Arizona: Gila County. Dozens of small chrysotile mines worked the Salt River district east of Globe. Our catalog lists many of them, including Johns-Manville's claims south of the Salt River.

Quebec, for context. For more than a century, Quebec's chrysotile belt was one of the great asbestos sources of the world, centered on Thetford Mines and the town of Asbestos, since renamed Val-des-Sources. The Jeffrey mine at Asbestos, owned for decades by Johns-Manville, was long called the largest asbestos mine in the world. A 1917 geology paper in our library describes the Black Lake–Thetford deposits. Quebec's last asbestos mines stopped producing around 2011 and 2012.

Mills and processing

Fiber had to be freed from the rock before it could be sold. In the mill, ore was crushed, dried and screened, and the fiber was separated out, graded and bagged. Every step made dust. Workers who ran crushers, cleaned screens, swept floors or loaded bags breathed it, and so did maintenance crews such as millwrights and mechanics who repaired the equipment.

Exposure didn't stop at the mill door. Tailings piles, haul roads and loading areas could spread fiber around the site, and in mining towns the dust reached homes.

Miners of other minerals: vermiculite, talc, taconite and gold

Many miners never dug asbestos on purpose. Their risk came from asbestos-type minerals mixed into the ore. How dangerous that was depends on the mineral, its shape and the dose, and the science is clearer for some mines than others.

Vermiculite: Libby, Montana. The Zonolite Company began mining vermiculite near Libby in the 1920s. W.R. Grace bought the operation in 1963, and the mine closed in 1990. EPA estimates the mine supplied over 70 percent of the vermiculite sold in the U.S. from 1919 to 1990. The ore was contaminated with amphibole asbestos that federal health agencies call Libby amphibole, a mix of tremolite, actinolite, richterite and winchite. The vermiculite was shipped to processing plants across the country and sold in products such as attic insulation and Zonolite masonry fill insulation. In 2009, EPA declared a public health emergency in Libby, the first time it had ever made that finding under the Superfund law. See the Libby mine page and our page on contaminated products.

Talc. Talc and asbestos can form in the same rocks. In the Gouverneur talc district of St. Lawrence County, New York, government investigators in the 1970s reported asbestiform tremolite and anthophyllite in the talc. Whether that talc causes mesothelioma has been fiercely disputed. A 2002 study concluded that two mesothelioma deaths among the workers were unlikely to be caused by talc dust. A 2012 reanalysis found at least five new mesothelioma cases among the same workers, at least five times the general-population rate, and concluded the talc dust could cause mesothelioma. See anthophyllite and tremolite.

Taconite: Minnesota's Mesabi Range. Taconite is a low-grade iron ore. Mining and processing it makes dust that contains elongate mineral particles (EMPs), fiber-shaped mineral pieces. Most of the EMPs taconite workers breathed were short and non-asbestiform, which are thought to be less harmful than true asbestos fibers. After an unusual number of mesothelioma cases turned up among taconite workers, the Minnesota Legislature asked the University of Minnesota to study the industry. Its 2014 final report found:

• mesothelioma about 2.4 times more common in the workers than in other Minnesotans;
• mesothelioma risk rising with years worked in the industry;
• about twice the mesothelioma risk among workers with above-median exposure to EMP dust, a finding the researchers called marginally significant;
• no link between EMP exposure and lung cancer.

The researchers couldn't say for certain whether the mesothelioma excess came from the ore dust, from commercial asbestos used in the plants, or from both. They also stressed that mesothelioma stayed rare: about 3 cases per 1,000 for a 30-year taconite worker who lives to 80, compared with about 1.4 per 1,000 for an average person.

Gold: the Homestake mine, South Dakota. The rock at Homestake contains cummingtonite-grunerite, an amphibole mineral that occurs there mostly in non-asbestiform form. An early study suggested more lung cancer among the miners, which led to further research. A NIOSH study of 3,328 miners, followed through 1990, found that lung cancer did not rise with dust exposure. Silica dust in the mine was strongly tied to deaths from silicosis. Based on these studies, we do not treat Homestake work alone as evidence of asbestos exposure. A Homestake miner who also worked around asbestos insulation or other asbestos products is a different matter.

Naturally occurring asbestos

Asbestos also occurs naturally in rock and soil in many states, and the U.S. Geological Survey has been mapping reported occurrences across the country. California's geological survey has mapped areas of western El Dorado County where naturally occurring asbestos is more likely, and federal health officials concluded that breathing it over a lifetime in the El Dorado Hills area could harm health. Quarrying, road building and grading in these areas can release fibers. Workers in that kind of earth-moving work should know whether their site sits on asbestos-bearing rock.

How mine safety rules changed

Miners are protected by the federal Mine Safety and Health Administration (MSHA), not by OSHA. For decades MSHA's asbestos limit was 2 fibers per cubic centimeter (f/cc) of air over an eight-hour shift. In 2008 MSHA cut that permissible exposure limit to 0.1 f/cc, matching OSHA. It also set a short-term limit of 1 f/cc averaged over 30 minutes. The rules cover metal and nonmetal mines, surface coal mines and the surface areas of underground coal mines, and appear at 30 CFR 56.5001, 57.5001 and 71.701.

These limits came long after most asbestos mining in the U.S. had ended. Most people with mining-related asbestos disease today were exposed decades ago, under far looser limits. Asbestos diseases usually appear 20 years or more after the exposure began.

Families of miners

Dust rode home on clothes, hair, boots and in the family car. The National Cancer Institute notes some evidence that family members of workers heavily exposed to asbestos face an increased risk of mesothelioma. See take-home exposure.

Libby is the starkest example. In a federal health screening of more than 6,600 Libby-area adults, about 18 percent had abnormalities of the lung lining on chest X-rays. Having worked for W.R. Grace, being older, having lived in a household with a Grace worker, and being male were the strongest predictors (Peipins 2003). Exposure in Libby also came from the town itself, not only from the mine.

Not every mining town showed this. The Minnesota taconite study found that spouses of taconite workers had about the same rate of lung scarring on X-ray as the general public.

Who may have a claim

You may have a claim if you or a family member:

• worked at an asbestos mine or mill in Vermont, California, Arizona or elsewhere, or handled raw fiber shipped from one;
• worked at the Libby vermiculite mine or at a plant that processed Libby vermiculite;
• mined or milled talc or other ore known to contain asbestos;
• lived with someone who did any of this work; and
• have been diagnosed with mesothelioma, lung cancer, asbestosis or another asbestos-related disease.

Several mining companies, including Johns-Manville, which mined asbestos, and W.R. Grace, which mined Libby vermiculite, went through bankruptcy and created bankruptcy trusts to pay claims. Other claims may be brought as lawsuits against companies still in business. Which path fits depends on where you worked, what you were exposed to, and your diagnosis. Learn more about asbestos trust claims and asbestos lawsuits. If you worked in a mine but don't have a diagnosis, our free chest X-ray with a B-read can check for asbestos scarring.