Geologic occurrences of erionite in the United States: an emerging national public health concern for respiratory disease

Our plain-English summary of Geologic occurrences of erionite in the United States: an emerging national public health concern for respiratory disease, by B.S. Van Gosen, T.A. Blitz, G.S. Plumlee, et al (Environmental Geochemistry and Health, 2013).

The study

• Authors: B.S. Van Gosen, T.A. Blitz, G.S. Plumlee, G.P. Meeker, M.P. Pierson
• Journal: Environmental Geochemistry and Health
• Published: 2013;35(4):419-30
• Type of article: Review
• Cited by: 31 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Erionite, a mineral series within the zeolite group, is classified as a Group 1 known respiratory carcinogen. This designation resulted from extremely high incidences of mesothelioma discovered in three small villages from the Cappadocia region of Turkey, where the disease was linked to environmental exposures to fibrous forms of erionite. Natural deposits of erionite, including fibrous forms, have been identified in the past in the western United States. Until recently, these occurrences have generally been overlooked as a potential hazard. In the last several years, concerns have emerged regarding the potential for environmental and occupational exposures to erionite in the United States, such as erionite-bearing gravels in western North Dakota mined and used to surface unpaved roads. As a result, there has been much interest in identifying locations and geologic environments across the United States where erionite occurs naturally. A 1996 U.S. Geological Survey report describing erionite occurrences in the United States has been widely cited as a compilation of all US erionite deposits; however, this compilation only focused on one of several geologic environments in which erionite can form. Also, new occurrences of erionite have been identified in recent years. Using a detailed literature survey, this paper updates and expands the erionite occurrences database, provided in a supplemental file (US_erionite.xls). Epidemiology, public health, and natural hazard studies can incorporate this information on known erionite occurrences and their characteristics. By recognizing that only specific geologic settings and formations are hosts to erionite, this knowledge can be used in developing management plans designed to protect the public.

In plain English

This U.S. Geological Survey paper compiled geologic records and was not a health study. The authors searched the geologic literature up to early 2012, plus recent unpublished findings, to update a 1996 list of U.S. erionite occurrences. Erionite, a zeolite mineral, is listed by the International Agency for Research on Cancer as a Group 1 known carcinogen. The updated list held 95 occurrences: 51 from the 1996 list and 44 added by this study. The authors described three geologic settings. The first was non-marine sedimentary layers, typically altered volcanic ash and clays, whose most common and largest deposits appear to have formed in lakes. The others were volcanic rocks altered by heated fluids, and cavities in basalt. The literature only occasionally described U.S. erionite as fibrous or wooly. For 32 of the 72 occurrences in the literature, its shape was not described. Sampling in northwestern South Dakota and southeastern Montana found erionite contents from trace amounts to as much as 20%. The authors concluded that not all erionite is fibrous and that their findings allow more targeted exposure and health assessments. They cautioned that the list is incomplete and depends on earlier studies having identified erionite correctly.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Literature-based compilation (review) of known natural erionite occurrences in the United States, updating an earlier 1996 U.S. Geological Survey database
• Who was studied: Natural erionite occurrences in the United States documented in the geologic literature as of early 2012, plus recent unpublished discoveries (gravel deposits and volcanic ash-rich rock units in western North Dakota, northwestern South Dakota and southeastern Montana)
• Exposure: Erionite, a zeolite mineral (the series includes erionite-Ca, erionite-K and erionite-Na), in fibrous and non-fibrous forms. The paper notes it is listed by the International Agency for Research on Cancer as a Group 1 known carcinogen. Other fibrous zeolites (mordenite, thomsonite, offretite) were also noted.
• Main results:
  • The updated database mapped 95 documented natural occurrences of erionite in the United States.
  • Of the 95 occurrences, 51 came from the 1996 compilation and 44 were additional occurrences identified by this study.
  • Erionite in the United States was found in three general geologic settings. The first is non-marine sedimentary layers typically composed of altered volcanic ash and clays; the most common and largest deposits appear to have formed in lake environments. The other two are silica-rich volcanic deposits altered by heated (hydrothermal) fluids, and linings of cavities and vesicles in basalt.
  • The literature only occasionally described U.S. erionite as fibrous or wooly. The text lists 15 sites where it was described this way.
  • Figure 2 maps 32 documented natural occurrences of fibrous erionite in the United States, plus 15 examples where erionite lines vesicles and cavities in basalt.
  • For 32 of the 72 erionite occurrences found in the literature, there was not enough information to tell whether the erionite was fibrous.
  • Reconnaissance sampling by Custer National Forest personnel of formations in northwestern South Dakota and southeastern Montana found erionite contents ranging from trace to moderate amounts, as much as 20%.
  • Mordenite, another zeolite, was identified at a large number of localities in the literature and was more often described as fibrous than erionite.
• The authors' conclusion: The authors concluded that not all erionite is fibrous and that it may not universally occur in readily respirable forms. They stated that their geologic observations provide an improved basis for epidemiological investigations and allow more targeted exposure and health assessments. They also stated that much more sampling and electron microscopy of erionite is needed at localities where its shape and composition are unknown.
• Limitations the authors state:
  • The compilation is not a complete inventory of erionite in the United States. It covers only occurrences documented in the literature plus recent unpublished discoveries.
  • The inventory relies on the referenced studies having identified erionite accurately.
  • Erionite can be difficult to tell apart from some other zeolite minerals, such as mordenite and especially offretite.
  • Precise mineral analyses were rarely provided in the source literature, so the occurrences could only be called 'erionite' without distinguishing the specific series member.
  • Entries in the database mostly represent erionite-bearing districts rather than single sites. The host rock unit can extend for many miles beyond the sampled locality.

Topics

Medical terms in this study, explained in our Lexicon: erionite, Zeolite, Mesothelioma, Cappadocia, Environmental Exposure, Occupational Exposure, Epidemiology.

Related studies

• Geological occurrence, mineralogical characterization, and risk assessment of potentially carcinogenic erionite in Italy — M. Giordani, M. Mattioli, et al. (2017)
• Erionite in road gravel associated with interstitial and pleural changes--an occupational hazard in western United States — P.H. Ryan, M. Dihle, et al. (2011)
• Environmental risk of mesothelioma in the United States: An emerging concern-epidemiological issues — F. Baumann, M. Carbone (2016)
• Lung diseases due to environmental exposures to erionite and asbestos in Turkey — S. Emri, A. Demir, et al. (2002)
• High incidence of lung cancer and malignant mesothelioma linked to erionite fibre exposure in a rural community in Central Mexico — M.A. Ortega-Guerrero, G. Carrasco-Núñez, et al. (2015)
• Patterns of c-fos and c-jun proto-oncogene expression, apoptosis, and proliferation in rat pleural mesothelial cells exposed to erionite or asbestos fibers — C.R. Timblin, G.D. Guthrie, et al. (1998)

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