FairWarining Reports

Report Renews Concern About Asbestos-Like Minerals at Sites in Arid West

Campground near The Castles, a massive rock formation in the Sioux District of the Custer National Forest in South Dakota (photo courtesy of the National Institute for Occupational Safety and Health).

Campground near The Castles, a massive rock formation with national landmark status in the Sioux District of the Custer National Forest in South Dakota (photo courtesy of the National Institute for Occupational Safety and Health).

Recent research is focusing new attention on an asbestos-like mineral, blamed for staggering rates of a deadly cancer in Turkey, that also is found in the rocks and soil of 13 Western states.

The U.S. Geological Survey has identified 95 sites where the mineral, erionite, exists. And a recent hazard assessment at one of the sites, in the Custer National Forest, found that some Forest Service workers are being exposed to erionite particles in airborne dust as they carry out routine maintenance chores.

The air tests were conducted in the Sioux district of the forest, which straddles the border between far southeastern Montana and the northwest corner of South Dakota. The report — by the National Institute for Occupational Safety and Health, or NIOSH, part of the U.S. Centers for Disease Control and Prevention — reached no conclusions about the level of risk. But it advised steps to reduce the risk of breathing dangerous fibers, such as avoiding use of gravel containing erionite and wetting soil when doing work that raises clouds of dust.

Catherine Beaucham, a NIOSH industrial hygienist who led the study, said in an interview that she doesn’t know what the risk is to the health of the workers. “What I’m comfortable saying is they need to take proper precautions to reduce exposure,” she said.

Erionite was described in a 2008 scientific report as “almost certainly the most toxic naturally occurring fibrous mineral known.” In the Cappadocia region of central Turkey, an erionite-rich area where stone containing the mineral was used to build homes, researchers found extremely high incidence of mesothelioma, a cancer of the lining of the lung or abdomen that is extremely rare in the U.S. In some of the Turkish villages rates of mesothelioma were off the charts—responsible for 40 percent to 50 percent of all deaths. In the U.S., where most mesothelioma victims are former asbestos workers, there are about 3,200 cases reported annually.

Concern about chance exposure to erionite followed the disclosure in 2005 that, for years, erionite-rich gravel mined in western North Dakota had been spread on parking lots, at recreation sites and on hundreds of miles of unpaved roads, including school bus routes. As reported by FairWarning, air tests along gravel roadways and in vehicles, including inside school buses, revealed erionite levels similar to those in some stricken Turkish villages.


Erionite, a naturally occurring asbestos-like mineral, has been found in rocks and soil at 95 locations in the West. Map adapted from “Geologic occurrences of erionite in the United States: an emerging national public health concern for respiratory disease”; Environmental Geochemistry and Health, August 2013

In North Dakota and the rest of the U.S., there have been no proven cases of mesothelioma stemming from erionite exposure. But experts say that is less than reassuring, because mesothelioma often develops 30 years or more after initial exposure, and when identified is automatically assumed to have been caused by occupational exposure to asbestos. The expansion of housing, roads and recreation in the arid expanses of the West has heightened concern about people breathing harmful dust from fibrous minerals.

Researchers in Mexico last year reported an unusual cluster of lung cancer and mesothelioma in the village of Tierra Blanca de Abajo in Central Mexico, attributing it to erionite in native rocks and soil.

Erionite is but one of about 400 naturally occurring fibrous minerals, most of them little studied. They are unregulated with the exception of asbestos, which actually is a commercial name for six regulated minerals that were heavily used to make insulating materials, floor and ceiling tiles, automotive brakes and many other products. When asbestos material is worn or broken, it can release microscopic fibers into the air. Over decades, hundreds of thousands of shipyard workers and others exposed on the job have been stricken with terminal illnesses such as asbestosis, lung cancer and mesothelioma, from breathing the brittle, lung-scarring fibers.

Health authorities have noted key physical similarities between some of the unregulated minerals, including erionite, and asbestos. Minerals that, when disturbed, can release microscopic particles that are longer than they are wide, and that don’t easily dissolve in the lung, “should be assumed [to be] capable of causing asbestos-related diseases,” said Christopher P. Weis, a toxicologist and senior advisor at the National Institute of Environmental Health Sciences. “It really doesn’t matter what they’re called.”

Chronic exposure to three fibrous minerals has taken a tragic toll on miners and residents of the town of Libby, Mont. The minerals were contaminants of vermiculite ore from a large mine that operated near the town from about 1920 to 1990. High rates of asbestos-related illnesses and deaths lingered long after closure of the mine. Along with mine workers, residents were exposed through use of the tainted vermiculite as home insulation, at recreation sites and in gardening projects around the town.

In 2014, a major highway project in southern Nevada was delayed for several months after University of Nevada geologists Brenda Buck and Rod Metcalf documented the presence of actinolite asbestos in rocks and soil in the construction area around Boulder City, about 30 miles southeast of Las Vegas. Tests ordered by transportation officials confirmed the presence of asbestos, though at concentrations they described as “generally low.” They resumed construction, but ordered measures to hold down dust, such as wetting down work areas and excavating during period of calm or low winds.

Then last May, a study in the Journal of Thoracic Oncology suggested a link between naturally occurring fibrous minerals and what it described as an unusual pattern of mesothelioma cases in southern Nevada.

Nevada health department officials–pointing out that the mesothelioma rate in Nevada is about average—attacked the study as scaremongering and tried to block it by revoking access to data from the state cancer registry. The authors wound up using federal data instead.

The study said that while mesothelioma normally strikes older men with workplace exposure to asbestos, in southern Nevada there were more victims than expected among women and people under 55. This, the study said, “suggests that environmental exposure to mineral fibers in southern Nevada may be contributing to some of these mesotheliomas.”

The hazard assessment in the Custer National Forest was requested by Forest Service officials and involved about a dozen employees. The NIOSH team tested rocks and soil to confirm the presence of erionite, and fitted employees with air samplers to measure airborne particles.

The highest concentration was .36 erionite fibers per cubic centimeter of air–more than three times the recommended asbestos exposure limit of .1 asbestos fibers. However, the report said a direct comparison was not possible because there are no standards for erionite.

Kurt Hansen, district ranger for the Sioux district in Camp Crook, S.D., said the NIOSH report, which was released in November but drew little attention, contained “no real surprises” because staff had known for some time about the presence of erionite.

He said the precautions recommended by NIOSH, such as keeping vehicle windows closed, are worthwhile, but noted that in the northern Great Plains, which gets little rain but plenty of wind, “there’s just no way to avoid dust generation.”

NIOSH previously conducted a similar evaluation of a Bureau of Land Management area near Cody, Wyo. In that case, tests for erionite in rocks, soil and air were negative. However, tests for silica, another lung hazard, revealed that some employees were exposed above occupational limits.

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About the author

Myron Levin is editor of FairWarning.

2 comments to “Report Renews Concern About Asbestos-Like Minerals at Sites in Arid West”

  1. Terry Trent

    Upon further review of the article, I do notice that there is a trap contained in the text above. A trap that has lead to widespread and unnecessary disease and death across our globe.

    It is only when we set aside occupational exposures to mineral fibers, and look closely at environmental exposures alone that we see more clearly that a prioritization of mineral fiber toxicity is of utmost importance. Although it is also seen in occupational exposures, but less clearly. The comment offered above by Dr. Chris Weis regarding assuming toxicity, “should be assumed [to be] capable of causing asbestos-related diseases,” is an error. The practice of this assumption, has lead United States Public Health directly into a trap, from which there appears to be no escape.

    No where can the results of that trap be better seen than in California, and that trap is a cautionary tale for the 400 natural occurring fibrous materials, that we will eventually have to deal with.

    In California there are approximately 10 million people living on surface deposits of Chrysotile asbestos. Chrysotile being the most common form of mineral fiber, approximately 95% of it. It has literally sucked the coffers dry, in poorly planned attempts and regulations to protect populations. The reason I say “poorly” is because we see very clearly today in Libby Montana, that there is no vast amount of money, no regulation we can throw at mineral fibers, once they have been released, to clean or protect, that actually works. We simply do not have any such technology available to us.

    But in California when the mineral fiber scenarios became very serious (meaning a much higher disease causing potential fiber type exposure to more and more people. Both Tremolite and Erionite), there was no money to deal with these scenarios. But worse than no money, there was a complete lack of philosophy. No mental or regulatory infrastructure.

    In much the same way that when I look at the price tag on a new Ferrari of a beach front home, I am left stuttering the words “that’s nice” with no chance or plan of how to obtain that wonderful piece of machinery or home, Public health in California, with the discovery of people being exposed to these increased potential fibers, was left muttering to themselves “that’s nice”, with no other action of any importance. Their fall back position, having no chance of actually stemming the disaster that their philosophy of “all fibers are equal” had created, was just more of the assumption that “all fibers are equal”.

    By the time we sort through the 400 mineral fibers, assuming them all to be equal, we will have amassed a body count among the fibers that we currently know are not equal at all, of such vast proportions, that we will not be able to recover any semblance of credibility on the subject.

    That particular scenario is in full view for anyone to see in El Dorado County California right now. Where public health has abandoned residents to exposures to Tremolite asbestos, and have run completely away, to hide actually, from these human exposures. All the while arguing the merits of assuming new and exotic fibers to be a threat. In this case magnesiohornblend, to be equally hazardous with all other fibers, with no earthly plan to do anything about any of it.

    That is what we see, the result of the trap of the Public health assumption. Public health firmly caught as deer in headlights, watching from the sidelines as these situations develop and evolve into huge human disasters. One after the next.

  2. Terry Trent

    I think it fair to add two more places of concern, that point to even more places. In El Dorado County California, last May, the largest Tremolite deposit ever described in the literature was discovered and confirmed in laboratory in North Carolina. That County had been moving residents onto uncontrolled surface Tremolite deposits since 1996. People’s homes! This fiber is one of three known fibers that cause human epidemics in the absence of occupational exposures. Tremolite, Crocidolite and Erionite. Although the County has since taken measures to protect these unfortunate residents, literature from as early as 1988 and the more recent work at the New Calaveras Dam project in California demonstrate, that water can’t be used effectively, and may even cause worse exposures in the long run, by breaking the hydrophobic bundles apart. Other measures are equally frustrated.

    Ambler Pennsylvania, the site of the largest asbestos dump in the United States, with people living all over it, and more planned, points to an even more frustrating bit of science….already known in Libby Montana, The most deadly of fiber exposures, (including erionite) are not measurable in Ambient air. Although Ambler is the site of dumping and high use of crocidolite fibers, all that can be found in the air is Chrysotile asbestos. Leading the University of Pennsylvania to erroneously conclude that the deaths there are being caused by Chrysotile. What is found in lung upon death is such areas are the three fibers I mention. But what is measured in Air is Chrysotile alone. The same thing is found in Cappadocia. Turkey. Excursion exposures are the almost exclusive cause of accumulation in lungs. Ambient air measurements are obsolete and dangerous.

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