Non-asbestiform elongate mineral particles and mesothelioma risk: Human and experimental evidence

Our plain-English summary of Non-asbestiform elongate mineral particles and mesothelioma risk: Human and experimental evidence, by J.E. Goodman, M.J. Becich, D.M. Bernstein, et al (Environmental Research, 2023).

The study

• Authors: J.E. Goodman, M.J. Becich, D.M. Bernstein, B.W. Case, J.H. Mandel, A.E. Nel, R. Nolan, N.U. Odo, S.R. Smith, E. Taioli, G. Gibbs
• Journal: Environmental Research
• Published: 2023;230:114578
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The presentations in this session of the Monticello II conference were aimed at summarizing what is known about asbestiform and non-asbestiform elongate mineral particles (EMPs) and mesothelioma risks based on evidence from experimental and epidemiology studies. Dr. Case discussed case reports of mesothelioma over the last several decades. Dr. Taioli indicated that the epidemiology evidence concerning non-asbestiform EMPs is weak or lacking, and that progress would be limited unless mesothelioma registries are established. One exception discussed is that of taconite miners, who are exposed to grunerite. Drs. Mandel and Odo noted that studies of taconite miners in Minnesota have revealed an excess rate of mesothelioma, but the role of non-asbestiform EMPs in this excess incidence of mesothelioma is unclear. Dr. Becich discussed the National Mesothelioma Virtual Bank (NMVB), a virtual mesothelioma patient registry that includes mesothelioma patients' lifetime work histories, exposure histories, biospecimens, proteogenomic information, and imaging data that can be used in epidemiology research on mesothelioma. Dr. Bernstein indicated that there is a strong consensus that long, highly durable respirable asbestiform EMPs have the potential to cause mesothelioma, but there is continued debate concerning the biodurability required, and the dimensions (both length and diameter), the shape, and the dose associated with mesothelioma risk. Finally, Dr. Nel discussed how experimental studies of High Aspect Ratio Engineered Nanomaterials have clarified dimensional and durability features that impact disease risk, the impact of inflammation and oxidative stress on the epigenetic regulation of tumor suppressor genes, and the generation of immune suppressive effects in the mesothelioma tumor microenvironment. The session ended with a discussion of future research needs.

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In plain English

This article summarized one Monticello II conference session, not a single original study. Presenters reviewed non-asbestiform elongate mineral particles (EMPs), such as cleavage fragments, and mesothelioma. A PubMed search using case-report terms for any form of mesothelioma or pleural or peritoneal cancer found 2660 papers from 1900 to 2022; "asbestiform" appeared in four, "non-asbestiform" in none. The epidemiology evidence on non-asbestiform EMPs was described as weak or lacking. Minnesota taconite miners, who are exposed to grunerite, had a mesothelioma mortality ratio about three times that of the state comparison population. An earlier case-control study (80 cases, 320 controls) reported a rate ratio of 2.25 (95% CI 1.13 to 4.5) for high versus low cumulative EMP exposure, but the role of non-asbestiform EMPs remained uncertain. Of 1444 patients in the National Mesothelioma Virtual Bank, 781 had work information, and construction was the most frequently recorded industry. Reviewed animal studies showed long, rigid multi-wall carbon nanotubes inducing mesothelioma. The authors concluded the evidence points to few if any non-asbestiform EMPs posing mesothelioma risk, but called for systematic comparison of people with mesothelioma with controls.

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: Workshop summary: a narrative review of the presentations at one session of the Monticello II conference, including a literature search of case reports and summaries of published and ongoing studies
• Who was studied: No single study population. The session covered published mesothelioma-related case reports (PubMed, 1900 to 2022), Minnesota taconite miners (work histories of over 68,000 miners), National Mesothelioma Virtual Bank patients diagnosed 2006 to 2020, and experimental animal studies of high aspect ratio engineered nanomaterials
• Exposure: Non-asbestiform elongate mineral particles (EMPs), including cleavage fragments, with grunerite in taconite mining as the main example. The session also discussed talc, carbon nanotubes, silicon carbide, erionite, sepiolite, palygorskite and vitreous fibers, and used asbestiform amphiboles for comparison
• Main results:
  • A PubMed search using "case reports" or similar terms for any form of mesothelioma or pleural or peritoneal cancer identified 2660 papers from 1900 to 2022. Of these, "asbestiform" occurred in only four publications and "non-asbestiform" in none
  • The session found the epidemiology evidence on non-asbestiform EMPs weak or lacking
  • The Minnesota Department of Health found that the standardized mortality ratio for mesothelioma in the taconite mining cohort was about three times higher than in the state comparison population
  • In the earlier case-control study by Lambert et al. (2016) of 80 cases and 320 controls among taconite workers, high versus low cumulative EMP exposure was associated with mesothelioma (rate ratio 2.25, 95% CI 1.13 to 4.5)
  • In the Lambert study, mesothelioma risk was not elevated for miners who worked in the eastern iron range, even though amphibole EMPs were present there
  • Current on-site sampling in the taconite mines found no asbestiform EMPs in any sample
  • Of 1444 National Mesothelioma Virtual Bank patients, 781 (54.1%) had information on industry and occupation
  • Among these National Mesothelioma Virtual Bank patients, the most frequently recorded industries were construction (161, 20.6%), iron and steel mills and steel product manufacturing (62, 7.9%), and the US Navy (45, 5.8%)
  • There are no in vivo biopersistence studies of cleavage fragments or of short amphibole asbestos fibers
  • In experimental animals, long, rigid multi-wall carbon nanotubes induced mesothelioma, while short, flexible ones did not
• The authors' conclusion: The authors concluded that the evidence to date points to few if any non-asbestiform EMPs posing a risk of mesothelioma. They called for a systematic study comparing the exposures of people with mesothelioma with those of appropriate controls. For taconite miners, they stated that the role of non-asbestiform EMPs in the mesothelioma excess remains uncertain.
• Limitations the authors state:
  • Case reports and epidemiology studies lacked clear descriptions, qualitative or quantitative, of exposures to non-asbestiform EMPs
  • In the Lambert taconite study, historical EMP exposure estimates were sparse
  • The Lambert study did not assess EMPs shorter than 5 μm
  • Many taconite mesothelioma cases in the state cancer registry were diagnosed from clinical presentation, sometimes without histological confirmation
  • Measurements of airborne exposure specifically to non-asbestiform EMPs are lacking
  • Because mesothelioma is rare, most occupational studies lack the statistical power to detect associations

Topics

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

Medical terms in this study, explained in our Lexicon: Non-Asbestiform, elongate mineral particles (EMPs), Mesothelioma, Monticello II Conference, Asbestiform, Epidemiology, Taconite, Grunerite.

Related studies

• A comparison of asbestos fiber potency and elongate mineral particle (EMP) potency for mesothelioma in humans — D.H. Garabrant, S.T. Pastula (2018)
• The epidemiologic evidence for elongate mineral particle (EMP)-related human cancer risk — P. Boffetta, K.A. Mundt, et al. (2018)
• A review of mortality associated with elongate mineral particle (EMP) exposure in occupational epidemiology studies of gold, talc, and taconite mining — J.H. Mandel, B.H. Alexander, et al. (2016)
• Comprehensive assessment of exposures to elongate mineral particles in the taconite mining industry — J. Hwang, G. Ramachandran, et al. (2013)
• The relationship between various exposure metrics for elongate mineral particles (EMP) in the taconite mining and processing industry — J. Hwang, G. Ramachandran, et al. (2014)
• Differential responses of murine alveolar macrophages to elongate mineral particles of asbestiform and non-asbestiform varieties: Cytotoxicity, cytokine secretion and transcriptional changes — T.O. Khaliullin, E.R. Kisin, et al. (2020)

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