Erionite exposure in North Dakota and Turkish villages with mesothelioma

Our plain-English summary of Erionite exposure in North Dakota and Turkish villages with mesothelioma, by M. Carbone, Y.I. Baris, P. Bertino, et al (Proceedings of the National Academy of Sciences of the United States of America, 2011).

The study

• Authors: M. Carbone, Y.I. Baris, P. Bertino, B. Brass, S. Comertpay, A.U. Dogan, G. Gaudino, S. Jube, S. Kanodia, C.R. Partridge, H.I. Pass, Z.S. Rivera, I. Steele, M. Tuncer, S. Way, H. Yang, A. Miller
• Journal: Proceedings of the National Academy of Sciences of the United States of America
• Published: 2011;108(33):13618-23
• Cited by: 151 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Exposure to erionite, an asbestos-like mineral, causes unprecedented rates of malignant mesothelioma (MM) mortality in some Turkish villages. Erionite deposits are present in at least 12 US states. We investigated whether increased urban development has led to erionite exposure in the United States and after preliminary exploration, focused our studies on Dunn County, North Dakota (ND). In Dunn County, ND, we discovered that over the past three decades, more than 300 miles of roads were surfaced with erionite-containing gravel. To determine potential health implications, we compared erionite from the Turkish villages to that from ND. Our study evaluated airborne point exposure concentrations, examined the physical and chemical properties of erionite, and examined the hallmarks of mesothelial cell transformation in vitro and in vivo. Airborne erionite concentrations measured in ND along roadsides, indoors, and inside vehicles, including school buses, equaled or exceeded concentrations in Boyali, where 6.25% of all deaths are caused by MM. With the exception of outdoor samples along roadsides, ND concentrations were lower than those measured in Turkish villages with MM mortality ranging from 20 to 50%. The physical and chemical properties of erionite from Turkey and ND are very similar and they showed identical biological activities. Considering the known 30- to 60-y latency for MM development, there is reason for concern for increased risk in ND in the future. Our findings indicate that implementation of novel preventive and early detection programs in ND and other erionite-rich areas of the United States, similar to efforts currently being undertaken in Turkey, is warranted.

In plain English

The study combined air sampling, mineral analysis, and cell and mouse experiments on erionite, an asbestos-like mineral. It compared air in Dunn County, North Dakota, with five Turkish villages, and North Dakota erionite with erionite from Old Sarihidir and Karain. More than 300 miles of Dunn County roads, including 32 miles of school bus routes, had erionite-containing gravel. Disturbing the gravel put erionite fibers into the air people breathed. Breathing-zone samples during sweeping and housekeeping in a road garage and an office measured 0.18 fiber structures per cubic centimeter by electron microscopy (0.06 by a phase-contrast-equivalent count). This was comparable to Boyali, where mesothelioma causes 6.25% of all deaths, and Karlik (7.41%). Except at roadsides, North Dakota levels were lower than in Turkish villages where mesothelioma caused 20 to 50% of deaths. Fibers from both places had the same average width and similar chemistry. Cell and mouse tests showed similar effects from both countries' erionite. The study did not measure disease in North Dakota residents. The authors concluded there is reason for concern about increased future risk in North Dakota.

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: Environmental exposure comparison (activity-based and stationary air sampling) combined with mineralogical analysis, in vitro human mesothelial cell experiments, and a short-term mouse injection experiment
• Who was studied: Air in Dunn County, North Dakota, compared with air in five Cappadocian villages in Turkey. The North Dakota samples were taken inside cars and school buses, along roads, in a road maintenance garage and a social services office, and at a ball field, a community parking lot and gravel pits. The Turkish villages were Karain, Sarihidir, Tuzkoy, Karlik and Boyali. The researchers learned of the North Dakota gravel use in 2006. The chemical comparison used Turkish erionite from Old Sarihidir, and the cell experiments used erionite from Karain (plus Oregon). The laboratory work also used primary human mesothelial cells and groups of three 21-day-old BALB/c mice. No human disease outcomes were measured in North Dakota.
• Exposure: Airborne erionite (and asbestos) released when erionite-containing gravel or dust was disturbed by driving, raking, sweeping, bicycle riding and housekeeping. In the lab, erionite from North Dakota, Oregon and Karain, Turkey was tested, and cells received 5 μg per square centimeter. Mice received a single 1 mg intraperitoneal injection of North Dakota erionite, Turkish erionite or crocidolite asbestos (positive control).
• Main results:
  • Over the past two to three decades, more than 300 miles of Dunn County roads had been paved with erionite-containing gravel. This included 32 miles of school bus routes, as well as parking lots, playgrounds and baseball fields.
  • When the gravel was disturbed in North Dakota, erionite fibers became airborne and reached the personal breathing zone.
  • North Dakota indoor personal breathing zone samples were taken during sweeping and housekeeping in a road maintenance garage and a social services office. They measured 0.18 structures per cubic centimeter by total transmission electron microscopy (TEM) and 0.06 by phase contrast microscopy equivalent (PCME). These were comparable to Boyali and Karlik, villages with reported mesothelioma mortality of 6.25 and 7.41%. In Boyali, the 6.25% is the share of all deaths caused by mesothelioma.
  • In North Dakota, mean erionite levels by total TEM were 0.10 structures per cubic centimeter inside school buses, 0.27 inside cars and 0.59 during bicycle riding on erionite-gravel roads. Peaks of 2.74 by total TEM (0.2 by PCME) were measured inside cars and school buses.
  • A stationary roadside sample near a North Dakota school bus stop measured 0.11 by total TEM and 0.01 by PCME. This exceeded all stationary roadside samples along the main roads of the Turkish villages.
  • Apart from roadside samples, North Dakota concentrations were lower than those in the Turkish villages with mesothelioma mortality of 20 to 50%. That mortality measure is reported in the same terms as Boyali's 6.25% share of all deaths. North Dakota outdoor raking samples were also lower than Turkish street-sweeping samples.
  • Average fiber width was 0.31 μm for both North Dakota and Turkish erionite. Average length was 2.20 μm for North Dakota fibers and 3.57 μm for Turkish fibers. The authors described the physical and chemical characteristics of the two as very similar, although a sodium-to-calcium ratio distinguished them.
  • Human mesothelial cells co-cultured with macrophages formed foci after 8 weeks of exposure to erionite. Mean focus counts were 78.67 for North Dakota erionite, 52.00 for Oregon erionite and 24.33 for Turkish erionite. No foci formed in the control cultures.
  • Erionite from both regions induced release of HMGB1 by mesothelial cells and of TNF-alpha by macrophages. The authors link these two signals to mineral fiber carcinogenesis.
  • Two weeks after injection, inflammatory cell infiltration and mesothelial hyperplasia were found in the peritoneum of mice given any of the fibers. Neither chronic inflammation nor cytoplasmic or extracellular HMGB1 staining was seen in vehicle-injected mice.
  • Asbestos was also found in indoor total TEM samples in North Dakota and in four of the Turkish villages. Outdoor asbestos was not detected in North Dakota.
• The authors' conclusion: The authors concluded that, given the 30- to 60-year latency of mesothelioma, there is reason for concern about increased future risk in North Dakota. They also concluded that preventive and early detection programs in North Dakota and other erionite-rich US areas are warranted.
• Limitations the authors state:
  • Air concentrations of erionite associated with increased mesothelioma risk have not been established.
  • The data do not allow complete exposure comparisons between North Dakota and Turkey.
  • The studies were limited to Dunn County, North Dakota.
  • Winds of 10 to 20 mph during much of the North Dakota outdoor activity-based sampling may have produced lower measured exposures than quiescent conditions like those in Turkey.
  • Fiber size measurements came from air samples. The processes that released and dispersed fibers differed between the locations, which may contribute to different size distributions.
  • The higher focus count with North Dakota erionite should not, on its own, be taken as evidence that it is more potent than Turkish erionite.
  • Precise data on past mesothelioma incidence in North Dakota are not available, because the state is not part of the SEER database.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: erionite, Mesothelioma, Malignant Mesothelioma, Mesothelial Cells, Latency.

Related studies

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• Ras oncoprotein expression in erionite- and asbestos-induced Turkish malignant pleural mesothelioma patients--a pilot study — A. Olut, P. Firat, et al. (2001)
• Erionite series minerals: mineralogical and carcinogenic properties — A.U. Dogan, M. Dogan, et al. (2008)
• 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)
• Lung diseases due to environmental exposures to erionite and asbestos in Turkey — S. Emri, A. Demir, et al. (2002)

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