The Presence of Asbestos in the Natural Environment is Likely Related to Mesothelioma in Young Individuals and Women from Southern Nevada

Our plain-English summary of The Presence of Asbestos in the Natural Environment is Likely Related to Mesothelioma in Young Individuals and Women from Southern Nevada, by F. Baumann, B.J. Buck, R.V. Metcalf, et al (Journal of Thoracic Oncology, 2015).

The study

• Authors: F. Baumann, B.J. Buck, R.V. Metcalf, B.T. McLaurin, D.J. Merkler, M. Carbone
• Journal: Journal of Thoracic Oncology
• Published: 2015;10(5):731-737
• Cited by: 83 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Inhalation of asbestos and other mineral fibers is known causes of malignant mesothelioma (MM) and lung cancers. In a setting of occupational exposure to asbestos, MM occurs four to eight times more frequently in men than in women, at the median age of 74 years, whereas an environmental exposure to asbestos causes the same number of MMs in men and women, at younger ages.

Methods: We studied the geology of Nevada to identify mineral fibers in the environment. We compared MM mortality in different Nevada counties, per sex and age group, for the 1999 to 2010 period.

Results: We identified the presence of carcinogenic minerals in Nevada, including actinolite asbestos, erionite, winchite, magnesioriebeckite, and richterite. We discovered that, compared with the United States and other Nevada counties, Clark and Nye counties, in southern Nevada, had a significantly higher proportion of MM that occurred in young individuals (<55 years) and in women.

Conclusions: The elevated percentage of women and individuals younger than 55 years old, combined with a sex ratio of 1:1 in this age group and the presence of naturally occurring asbestos, suggests that environmental exposure to mineral fibers in southern Nevada may be contributing to some of these mesotheliomas. Further research to assess environmental exposures should allow the development of strategies to minimize exposure, as the development of rural areas continues in Nevada, and to prevent MM and other asbestos-related diseases.

In plain English

This study asked whether mesothelioma deaths in southern Nevada followed a pattern the authors link to environmental, rather than workplace, exposure to mineral fibers. The authors analyzed Centers for Disease Control and Prevention mesothelioma death data for 1999 to 2010. They compared Clark and Nye counties (133 deaths) with other Nevada counties and with the rest of the United States, and compiled published reports of fibrous minerals in Nevada. In Clark and Nye counties the male-to-female ratio was 2.69 to 1. That was statistically significantly lower than in other Nevada counties (6.33 to 1) and in the rest of the country (4.97 to 1). Deaths under age 55 made up 11.28% in Clark and Nye counties versus 6.21% in other U.S. counties, a statistically significant difference. Compared with other Nevada counties (9.09%), the difference was not statistically significant. In this younger group, men and women were reported at 1 to 1. Reported fibrous minerals in southern Nevada included actinolite asbestos, tremolite, erionite, winchite, magnesioriebeckite and richterite. The authors concluded that environmental exposure may be contributing to some of these mesotheliomas. They said lung fiber analyses are needed to further prove causality.

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: Descriptive comparison of mesothelioma death data by county, sex and age group, combined with a compilation of published geological reports of fibrous minerals in Nevada
• Who was studied: Malignant mesothelioma deaths recorded by the CDC in the United States, 1999 to 2010. This was 31,526 cases in total: 133 in Clark and Nye counties (southern Nevada) and 31,408 in all other U.S. counties. The count for the other Nevada counties was not shown for confidentiality reasons. Seven states with known asbestos industry were also compared.
• Exposure: Naturally occurring fibrous minerals in Nevada, compiled from published sources. These included actinolite asbestos, tremolite, erionite, winchite, magnesioriebeckite and richterite (Table 1 marks these as present in southern Nevada). Winchite, magnesioriebeckite, actinolite and richterite were also reported across the Colorado River in northwestern Arizona. No individual exposure or residential histories of the cases were available.
• Main results:
  • In Clark and Nye counties the male-to-female mesothelioma death ratio was 2.69:1, significantly lower than in all other Nevada counties combined (p = 0.0468)
  • In all other Nevada counties combined, the male-to-female ratio was 6.33:1
  • The Clark and Nye county sex ratio was also significantly lower than the ratio for the rest of the United States, which was 4.97:1 (p = 0.0422)
  • Mesothelioma deaths under age 55 were 11.28% of deaths in Clark and Nye counties versus 6.21% in all other U.S. counties (p = 0.0249)
  • Compared with all other Nevada counties, where deaths under 55 were 9.09%, the difference was not statistically significant (p = 0.8075 in Table 2)
  • Among younger cases in Clark and Nye counties, the article reports 21 mesotheliomas with a 1:1 sex ratio (11 males and 10 females). The youngest were aged 15 to 19.
  • The share of women was the same (49.1% in 2000) in Clark and Nye counties and in other Nevada counties, so the authors said population makeup did not explain the low sex ratio
  • In seven U.S. states with known occupational asbestos exposure, male-to-female ratios ranged from 4.20 (Pennsylvania) to 8.67 (Alaska). The share of deaths under 55 in those states ranged from 2.29% (New Hampshire) to 8.62% (Alaska).
  • From CDC statistics, Nevada's age-standardized mesothelioma incidence for 2006 to 2010 was 10 per million per year (95% CI 8 to 12), similar to the U.S. mean of 10 per million (95% CI 10 to 10)
  • Mapping fibrous actinolite in Clark County identified 230 samples of asbestos-bearing rock and soil, mostly from analyses for the Boulder City Bypass/Interstate 11 construction
• The authors' conclusion: The authors concluded that the higher percentage of women and of people under 55, the 1:1 sex ratio in that age group, and the presence of naturally occurring asbestos suggest that environmental exposure to mineral fibers in southern Nevada may be contributing to some of these mesotheliomas
• Limitations the authors state:
  • Confidentiality rules prevented showing detailed data for subgroups
  • Nevada is a retirement destination, so some people may have been exposed elsewhere. The authors said focusing on younger cases reduced this risk.
  • No lung fiber content analyses were done; the authors said these are needed to further prove causality
  • Residential histories and dust-related activities of the cases were not available

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Mineral Fiber, Lung Cancer, Occupational Exposure, Environmental Exposure, Carcinogenic, Actinolite, erionite.

Related studies

• Reply to "No Increased Risk for Mesothelioma in Relation to Natural-Occurring Asbestos in Southern Nevada" — F. Baumann, B.J. Buck, et al. (2015)
• Researchers explore possible link between mesothelioma and dust emissions in southern Nevada — L.H. O'Hanlon (2013)
• No Increased Risk for Mesothelioma in Relation to Natural-Occurring Asbestos in Southern Nevada — P.S. Pinheiro, H. Jin (2015)
• Investigating palygorskite's role in the development of mesothelioma in southern Nevada: Insights into fiber-induced carcinogenicity — D. Larson, A. Powers, et al. (2016)
• Global, regional, and national burden of ovarian cancer among young women during 1990-2019 — Q. Zhuang, G. Gu, et al. (2025)
• Malignant mesothelioma in construction workers: the Apulia regional mesothelioma register, Southern Italy — L. Vimercati, D. Cavone, et al. (2019)

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