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Erionite: An Emerging North American Hazard

Categories: Respiratory Health

Erionite is a naturally occurring mineral that belongs to a group of silicate minerals called zeolites. It is usually found in volcanic ash that has been altered by weathering and ground water. Like naturally occurring asbestos, deposits are present in many Western states (see map).1 Erionite can occur in a fibrous form. Disturbance of this material can generate airborne fibers with physical properties and health effects similar to asbestos. For example, it has long been known that residents of some Turkish villages where erionite-containing rock was used to construct homes have a remarkably high risk for development of malignant mesothelioma.2

Occurrences of erionite in sedimentary rocks of the western US. From Sheppard (USGS), 1996.

Occurrences of erionite in sedimentary rocks of the western US. From Sheppard (USGS), 1996. Click the image for a list of the identified locations.

Until recently, erionite was not generally considered to be a potential hazard in North America, in part because relatively little risk for exposure was seen. However, evidence has slowly accumulated linking exposure to erionite with serious adverse health effects in North America, and suggesting that some workers may have a greater potential for exposure than previously recognized. The first North American with erionite-related lung disease was recognized in Utah and reported in 1981.3 He was a road construction worker who lived in an area rich in zeolite deposits. He had extensive parenchymal and pleural fibrosis and had a lung biopsy revealing the presence of both fibrous and nonfibrous particles which had compositions determined by energy-dispersive X-ray analysis to be consistent with erionite. In 2008, a mesothelioma cluster was described in the vicinity of a small village in a zeolite-rich region of central Mexico.4 The same year, 2 additional cases were reported from a neighboring Mexican state.5 One of them underwent lung biopsy and examination of tissue showed a high burden of erionite. In 2009, a mesothelioma case associated with pulmonary interstitial fibrosis, pleural plaque formation and substantial lung burden of erionite was documented in a man who had lived in Mexico and the United States.6 In 2011, the results of a study conducted in southwestern North Dakota were reported.7 The study was motivated by the realization that, since the 1980s, gravel pits had been excavated in areas containing erionite deposits and the gravel used to surface local roads and other areas. Ambient and activity-based sampling was performed and demonstrated the potential for airborne fiber exposures. Individuals with potentially high exposures were identified and underwent careful clinical evaluation. Two with histories of road maintenance work (one had also worked in a local gravel pit) were found with mild bilateral localized pleural changes with calcification and minimal unilateral and bilateral lower lobe interstitial changes that could only be seen by CT scan. Other than erionite, neither reported potentially causative exposures.

There are no regulatory or consensus standards or occupational exposure limits (OEL) for airborne erionite fibers. Development of a quantitative OEL awaits development of a standardized, validated exposure assessment method and quantitative evaluation of risks associated with given exposures. Still, The National Toxicology Program has designated erionite to be a known human carcinogen and a study by the U.S. Geological Survey found that erionite fibers from the Cappadocian region of Turkey, North Dakota, and Oregon were chemically and morphologically similar.8,9 Little is known about exposures currently experienced by US workers. However, erionite-related disease has most often been reported in road construction and maintenance workers with potential occupational exposures to erionite-containing gravel used in road surfacing. Also, one case had worked in an erionite-containing gravel pit (but had also been a road worker). Although it is reasonable to be concerned, erionite-related clinical disease has not yet been reported in other US workers engaged in activities that might crush erionite-containing rock or stir up dust in soils/gravel that contain erionite.

Erionite fibers only pose a hazard if they are disturbed and become airborne, and control recommendations should focus on reducing the potential for exposure to airborne erionite fibers. Activity-based breathing zone air sampling has confirmed that when gravels containing erionite are disturbed, erionite fibers can become airborne.10 Intensity of these exposures may vary due to a number of factors, including the weather conditions (damp vs. dry, windy vs. calm), the intensity with which erionite-containing materials are disturbed and the concentration of erionite in the gravels being disturbed. However, bulk gravel erionite concentrations alone are not a reliable predictor of air concentrations, as disturbance of gravels containing erionite in “trace” amounts (< 0.2%) can sometimes result in relatively high airborne fiber concentrations.

These data support the need to implement precautions to protect workers by limiting the generation and inhalation of dust known or thought to be contaminated with erionite. A reasonable approach based on current information would be to take precautions such as those described in existing guidance for working with asbestos (Occupational Safety and Health Administration [OSHA] 29 CFR 1910.1001). Existing recommendations for working in areas with naturally occurring asbestos may be particularly relevant to reducing outdoor occupational erionite exposures.11

Risk reduction recommendations to limit erionite exposures of workers who engage in activities that disturb erionite-containing gravel/soil or crush rocks that contain erionite can include:

  • Training workers about the potential hazards of erionite and control methods for reducing the potential for exposure
  • Knowing where erionite containing material is present and will be encountered prior to beginning any work
  • Avoiding the use of erionite containing aggregate whenever possible
  • Using wet methods to reduce dust generation for road and other work such as in quarries where erionite is present (e.g., when drilling rock, apply water through the drill stem to reduce airborne dust, or use a drill with a dust collection system)
  • Limiting the number of workers who will be engaged in work with erionite
  • Establishing decontamination protocols including change of clothing, showering before leaving the worksite, and appropriate cleaning/disposal of personal protective equipment
  • Ensuring work clothing is not washed at home to prevent erionite fibers from being brought home on work clothes and boots
  • Prohibiting dry sweeping, the use of leaf blowers, or the use of compressed air for cleaning
  • Protecting employees with personal protective equipment, including respiratory protection. Note: An occupational safety and health professional should be consulted for specific guidance about the most appropriate personal protective equipment that should be used for the work being conducted.
  • Prohibiting eating, drinking, or smoking in dusty work areas where erionite fibers may be airborne. Workers should move away from the work area for breaks and wash their hands and face before eating, drinking, or smoking.
  • Establishing protocols for vehicle use on erionite containing roads (drive slowly, vents closed, windows up)
  • Wet washing equipment and vehicle exteriors, and wet cleaning/High Efficiency Particulate Air (HEPA) filter vacuuming of vehicle interiors.
  • Following Environmental Protection Agency (EPA) procedures for proper dispose of waste and debris that contains erionite.
  • Limiting bystander exposure by preventing visitors and coworkers from standing in work areas where erionite fibers may become airborne.

Although much remains to be learned about erionite in the US, airborne occupational erionite fiber exposures should be considered at least as hazardous as asbestos fiber exposures and similar preventive measures used. We look forward to working with our scientific colleagues to stay informed about further occupational health data relating to erionite as more studies become available, and we invite you to consider what scientific and technical questions you would have about this emerging occupational health issue. 

Dr. Weissman is Director of the NIOSH Division of Respiratory Disease Studies.

Mr. Kiefer is Director of the NIOSH Western States Office.

Works Cited

  1. Sheppard R. Occurrences of erionite in sedimentary rocks of the western United States. Denver, CO: US Department of the Interior, US Geological Survey; 1996. Open File Report 96�018.
  2. Carbone M, Baris I, Bertino P, Brass B, Corertpay S, Dogan A, Gaudino G, Jube S, Kanodia S, Partridge C, Pass H, Rivera Z, Steele I, Tuncer M, Way S, Yang H, Miller A (2011). Erionite exposure in North Dakota and Turkish villages with mesothelioma. Proc Natl Acad Sci U S A 108(33):13618-13623.
  3. Rom W, Casey K, Parry W, Mjaatvedt C, Moatamed F (1983). Health implications of natural fibrous zeolites in the intermountain west. Environ Res 30:1-8.
  4. Ilgren EB, Ortega Brena M, Castro Larragoitia J, et al. A reconnaissance study of a potential emerging Mexican mesothelioma epidemic due to fibrous zeolite exposure. Indoor Built Environ. 2008;17:496�515.
  5. Ilgren EB, Pooley FD, Larragoitia JC, et al. First confirmed erionite related mesothelioma in North America. Indoor Built Environ. 2008;17:567�568.
  6. Kliment CR, Clemens K, Oury TD. North american erionite-associated mesothelioma with pleural plaques and pulmonary fibrosis: a case report. Int J Clin Exp Pathol. 2009;2(4):407-10. Epub 2008 Nov 25.
  7. Ryan P, Dihle M, Griffin S, Partridge C, Hilbert T, Taylor R, Adjei S, Lockey J (2011). Erionite in road gravel associated with interstitial and pleural changes � an occupational hazard in Western United States. J. Occup Environ Med 53(8): 892-898.
  8. NTP-NIEHS. Report on carcinogens, twelfth edition (2011). Erionite. CAS No. 66733-21-9. [, accessed 11/4/11].
  9. USGS (2010). Chemical and morphological comparison of erionite from Oregon, North Dakota, and Turkey. Prepared for the U.S. Environmental Protection Agency, Region 8. U.S. Department of the Interior, U.S. Geological Survey. Open-File Report 2010-1286.
  10. EPA (2007) Analytical results report; Dunn County erionite, Killdeer, Dunn County, North Dakota. United States Environmental Protection Agency, Contract No. EP-W-05-050
  11. ATSDR-CDC. Asbestos: for workers involved in activities that disturb soil or generate dust in areas with naturally occurring asbestos. [, accessed 10/22/2011].

Public Comments

Comments listed below are posted by individuals not associated with CDC, unless otherwise stated. These comments do not represent the official views of CDC, and CDC does not guarantee that any information posted by individuals on this site is correct, and disclaims any liability for any loss or damage resulting from reliance on any such information. Read more about our comment policy ».

  1. November 22, 2011 at 10:31 am ET  -   Michael

    For the benefit of blog readers, please provide full citations for the 11 references cited.

    Link to this comment

    • AUTHOR COMMENT November 22, 2011 at 12:12 pm ET  -   David Weissman and Max Kiefer

      Thank you for contacting us. At the time you posted your comment it was necessary to click on “Works Cited” under our signature lines to see the references. Now we have listed the full references in the blog to make it easier for readers.

      Link to this comment

  2. November 22, 2011 at 12:11 pm ET  -   Patrick

    Any way to get a listing of the sites referenced on the map or did I miss a hyperlink somewhere?

    Link to this comment

    • AUTHOR COMMENT November 22, 2011 at 3:03 pm ET  -   David Weissman and Max Kiefer

      Thank you for you suggestion. The location of all sites listed on the map can now be found by clicking on the map. Specific locations for these sites are also available in reference #1.

      Link to this comment

  3. November 22, 2011 at 4:59 pm ET  -   Frank Ehrenfeld

    I’m working with a newly charged ASTM D22.07 committee to develop analytical methods for erionite testing. I’ll be in Yellowstone (51 on your map) in August 2012. Anyone I can contact about getting some samples to test by our group? Thanks.

    Link to this comment

    • AUTHOR COMMENT November 23, 2011 at 9:17 am ET  -   David Weissman and Max Kiefer

      Thank you for your comment. We will contact you directly to discuss.

      Link to this comment

  4. November 22, 2011 at 5:02 pm ET  -   Stuart

    Would you be able to post these sites on Google Earth so we can get a better idea of where they are located and what to avoid?

    Link to this comment

    • AUTHOR COMMENT November 23, 2011 at 2:51 pm ET  -   David Weissman and Max Kiefer

      Our intent was not to encourage people to avoid these areas, but to provide information about the US distribution of naturally occurring erionite deposits as reported by the USGS in 1996 so that employers and workers would be aware of the possibility of a potential for job-related exposure similar to that reported in North Dakota, where gravel used to surface roads came from a pit containing erionite. Those concerned about the possibility of occupational exposure to airborne fibers of such materials should consult with an expert familiar with the geology of their area and knowledgeable about the presence of erionite containing quarry pits.

      Link to this comment

  5. November 22, 2011 at 9:43 pm ET  -   Andrew Robbins

    No mineral is safe for you/us to inhale! Not one.

    Link to this comment

  6. November 23, 2011 at 1:52 pm ET  -   Dr. Jacob D Paz

    Yucca Mountain Project the proposed high nuclear repository (YMP) and Erionite In 2004, DOE employees at Yucca Mountain Project YMP complained of exposure to high levels of silica and erionite, a potent carcinogen, erionite were located in various veins at YMP This complain resulatt in a Congregational Hearing in Las Vegas, NV March 16, 2004. About 1200 employees or more were exposed were exposed to eironite they and had X-ray evaluation, but no CT or MRI were taken of these workers what is the medical outcome is unknown.

    Figure 1. Congressional Hearing on Exposure to Silica and Erionite dust at YMP (Las Vegas Review Journal March 16, 2004)

    There are additional health and safety concerns. During tunneling operations at Yucca Mountain Project the proposed high nuclear repository located 100 mile north of Las Vegas NV. YMP, waste contaminated with erionite was dumped onto the open ground and pose health risks for visitors, employees and the environment. The further use of tunnel boring machines and conveyor belts during tunneling operations would or had increased erionite air contaminant exposure spread within the tunnel. In the Environmental Impact Statement 2008 recommended use of use of “administrative control” to minimize exposure to erionite this method is impractical and is not used in asbestos abatement. Asbestos removal must use personal protection equipment (PPE) that includes respirators and protective clothing. Negative room pressure, and separate room for PPE change is used to prevent releases of asbestos contamination of employees and the releasing asbestos into the environment. The health and Safety precaution in the EIS�s are inadequate and posed health risk to workers and visitors.

    Figure 2. OSHA Asbestos Disposal
    Figure 3. Erionite Disposal At YMP site
    Methods ( (LV Review The EPA and OSHA have very stringent regulations for asbestos disposal, such as double bagging. Currently, there are no EPA or OSHA regulations for handling, disposal, and health and safety precautions for erionite, the only OSHA regulation applicable is 5 (a)(1).)

    Link to this comment

  7. November 24, 2011 at 8:29 am ET  -   M Geyer

    Given the map and sites listed as “occurrences of erionite,” I notice that many of these “sites” are identified as: drill holes. Please explain.

    Are these “sites” actually locations where core samples were collected from borings? If so, just what is the hazard? If this material is not surficial or near surface…so what! I’ve identified galena, arsinate, tremolite, chrysotile, and cinibar, to name a few “hazardous” minerals, in core samples at drill sites. Given that these mineral were not surficical, there is no risk of inhalation.

    Link to this comment

    • AUTHOR COMMENT November 23, 2011 at 2:51 pm ET  -   David Weissman and Max Kiefer

      Thank you for your comment; our intent was not to make a hazard determination but provide information about the US distribution of naturally occurring erionite deposits as reported by the USGS in 1996 so that employers and workers would be aware of the possibility of a potential for job-related exposure similar to that reported in North Dakota, where gravel used to surface roads came from a pit containing erionite. You are correct, erionite fibers only pose a hazard if they are disturbed, become airborne, and present a risk of inhalation.

      Link to this comment

  8. November 27, 2011 at 7:03 am ET  -   Michel H Nazaire

    Thank you for the data concerning erionite and its potentially causative exposures:the ideal objective is to preclude occupational exposure detrimental to the health …People working in heathful and comfortable environment are more productive…

    Link to this comment

  9. November 28, 2011 at 9:17 am ET  -   Chris

    Hundreds of thousands of tons of sand are being transported to the Eastern United States from the identified region for “fracking” of natural gas wells. The sand is then transloaded to trucks at various rail sidings with considerable sand dust being created. This sand is then transported to drilling site sand hogs for use in the drilling process. Considering the properties described above and the purpose of using this sand it seems possible. Do you have knowledge of these sands being derived from these erionite deposits?

    Link to this comment

    • AUTHOR COMMENT December 1, 2011 at 6:37 pm ET  -   David Weissman and Max Kiefer

      Thank you for your question and for raising this as a potential occupational health issue. If sands are being derived from volcanic ashes in erionite-rich regions, it is possible that erionite could be present in some of these materials. However, currently available information does not allow us to determine if this is, or is not, the case. It has been documented that silica is present in fracking material. For more information on silicosis see the recent blog The Continuing Persistence of Silicosis.

      Link to this comment

  10. December 2, 2011 at 6:44 pm ET  -   Genevieve

    we at Mesothelioma Lawsuits also discuss this threats in great details. its really alarming to have this kinds of hazards in our environment today and so we should act now or never.

    Link to this comment

  11. January 19, 2012 at 12:37 pm ET  -   Kathie Marsaglia

    My guess is that Site 14 near Shoshone refers to erionite in altered tuffs in the Tecopa lake beds, a place visited by thousands of geologists over the years. Should I reconsider taking my students out to examine these units? Unfortunately, I have distinct “dusty” memories of camping in the wash there on a few windy nights. It would be great to have some idea of the relative dangers associated with each of your numbered localities.

    Link to this comment

    • AUTHOR COMMENT January 23, 2012 at 1:34 pm ET  -   David Weissman and Max Kiefer

      Thank you for your question. To answer it, we would need to have risk assessment information similar to that performed by EPA to assess environmental risks associated with naturally occurring asbestos deposits in California’s Clear Creek Management Area (see ). We do not have similar risk assessment information about sites where erionite was found in rock samples in the 1996 USGS report (Sheppard 1996). Also, we do not have similar measurements of airborne erionite fiber exposures or knowledge of the potential for airborne erionite fiber exposures at these sites. Given that, it is not possible to estimate what, if any, transient exposure could occur from camping in the identified areas. As we discuss in the blog, the reported cases of erionite-related disease have thus far been in those with risks for high levels of exposure, such as those using contaminated gravel for road work or excavating such gravel from contaminated pits.

      Link to this comment

  12. January 26, 2012 at 6:54 pm ET  -   Beth Nichols Boyd

    The following caption accompanies a map (and article) in the February, 2012 issue of EARTH magazine:
    “Map of occurrences of erionite in sedimentary rocks of the western United States. Since the map was produced in 1996, erionite deposits have also been found in Washington. A full listing of the locations identified here can be found at [].”

    This url was no longer correct but linked to the page where this comment box is located.

    My question? I don’t see where to access the full listing of the locations shown in the map. Instructions, please.

    Thank you.

    Link to this comment

  13. February 6, 2012 at 3:14 pm ET  -   Berthin Hyde

    The USGS study references sedimentary rock-containing zeolites in their study. Zeoloites commonly are secondary minerals in volcanic rocks. Volcanic rocks are commonly used as roadbed and are ground up and applied as “sand” to roads during icey conditions. Do you have information on:
    1) studies that have sought to determine the Erionite (zeolite) presence/absence in volcanic rocks? Eastern Washington and other western states have a lot of vesicular basalt with zeolites used in roadbeds.
    2) groundwater/drinking water studies that evaluate Erionite (zeolite) concentrations? There are many aquifers and surface waters that are within or come in contact with zeolites. and
    3) whether Erionite could pose a health risk if ingested (ie to the digestive system by drinking) rather than the respiratory system?

    Berthin Hyde

    Link to this comment

    • AUTHOR COMMENT February 7, 2012 at 2:15 pm ET  -   David Weissman and Max Kiefer

      Thank you for your excellent questions. Unfortunately, there is still much to learn. The 1996 USGS study referenced in the blog is the only currently-available national survey for presence of erionite that we are aware of. Also, we cannot provide information about levels in the US water supply or risks related specifically to ingestion into the GI tract. Clearly, more research is needed on this topic. We hope the blog has increased awareness of this issue and will help to encourage additional studies.

      Link to this comment

  14. August 19, 2012 at 12:08 pm ET  -   Christina Nolen

    Deposits of fibrous erionite are located in Arizona, Nevada, Oregon, and Utah. These zeolite beds may be up to 15 feet thick and may lie in surface outcroppings. Erionite fibers have been detected in samples of road dust in Nevada and U.S. residents of the Intermountain West may be potentially exposed to fibrous erionite in ambient air. In the summer of 2009 North Dakota began a study of possible erionite exposure among residents. Erionite has also been identified in samples from the Tertiary Arikaree Formation in southeast Montana and northwest South Dakota.

    Link to this comment

  15. February 3, 2014 at 2:07 am ET  -   David Dasley

    I have never been aware about the looks of erionite. I wonder if you can provide photo of what it look like.

    David Dasley

    Link to this comment

  16. September 11, 2014 at 9:00 am ET  -   manchesterunited fc

    Existing recommendations for working in areas with naturally occurring asbestos may be particularly relevant to reducing outdoor occupational erionite exposures.

    Link to this comment

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