A review of the cohorts with environmental and occupational mineral fiber exposure

Our plain-English summary of A review of the cohorts with environmental and occupational mineral fiber exposure, by S. Metintas, G. Ak, M. Metintas (Archives of Environmental & Occupational Health, 2019).

The study

• Authors: S. Metintas, G. Ak, M. Metintas
• Journal: Archives of Environmental & Occupational Health
• Published: 2019;74(1-2):76-84
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The aim of the study was to examine factors associated with Malignant Mesothelioma (MM) incidence rate of the groups with occupational asbestos and environmental asbestos or erionite exposure in rural area. In this ecological study, a total of 21 cohort datasets (8 environmental and 13 occupational) were evaluated. Data were analyzed using a multiple linear regression analysis model. In environmental cohorts, the risk of MM incidence was higher in women and people exposed to erionite. In this cohort, the incidence rate of MM increased as the median exposure time increased, while the incidence decreased as the median cumulative exposure dose increased. In occupational cohorts, the incidence rate of MM was positively correlated with the median cumulative exposure dose. The risk of mesothelioma was lower in those exposed to tremolite than others. Environmental asbestos exposure is as important as occupational exposure to develop MM, and it has its own unique exposure features on the risk of MM.

In plain English

This article, titled a review, was an ecological study that pooled published data from 21 cohort datasets from 27 publications. Eight were rural groups exposed environmentally to asbestos or erionite (in Turkey, Karain emigrants in Sweden, and Metsovo, Greece), and 13 were asbestos worker groups. Together they had 1,204 malignant mesothelioma cases. The pooled mesothelioma rate per 100,000 person-years was 50.50 for males (95% CI 22.10 to 78.90) and 65.23 for females (32.45 to 98.00) in the environmental cohorts, and 40.20 for males (31.60 to 48.80) and 24.90 for females (2.00 to 49.90) in the occupational cohorts. In the environmental cohorts, higher rates were associated with being female, erionite exposure and longer exposure time, and lower rates with higher cumulative dose. In the occupational cohorts, higher rates were associated with higher cumulative dose, older age at first exposure, and chrysotile and crocidolite compared with tremolite. The authors concluded that rates in environmental cohorts were as substantial as in occupational cohorts. They noted limitations typical of ecological studies, variation among occupational cohorts, and few studies with usable exposure data.

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: Ecological study that pooled published cohort data, titled as a review. Rates were pooled with a random effects model and analyzed with multiple linear regression.
• Who was studied: 21 cohort datasets from 27 publications. Eight were environmental cohorts (Eskisehir, Turkey; Karain, Turkey; Karain emigrants in Sweden; Metsovo, Greece; each split by sex). Thirteen were occupational cohorts (Pistoia and Casale Monferrato, Italy; France; Great Britain; South Africa; Quebec; Libby, Montana; Wittenoom, Western Australia). Together they had 1,204 malignant mesothelioma cases over 2,299,559 person-years, with follow-up periods ranging from 1940 to 2009.
• Exposure: Environmental exposure meant asbestos or erionite in materials in the living environment in rural settings, such as soil used for plastering or whitewashing, or erionite in building stone. Occupational exposure meant asbestos in workplaces such as cement plants, mines, mills and manufacturing. Fiber types were chrysotile, amosite, crocidolite, tremolite, anthophyllite, actinolite and erionite. Median exposure time was 49.0 years in environmental cohorts and 18.5 years in occupational cohorts. Median cumulative dose was 4.7 f/ml-yr in environmental cohorts and 8.7 f/ml-yr in occupational cohorts.
• Main results:
  • Of the 1,204 mesothelioma cases, 1,103 were in the occupational cohorts and 101 in the environmental cohorts.
  • Pooled mesothelioma incidence rates in the environmental cohorts were 50.50 per 100,000 person-years for males (95% CI 22.10 to 78.90) and 65.23 per 100,000 for females (95% CI 32.45 to 98.00).
  • Pooled mesothelioma incidence rates in the occupational cohorts were 40.20 per 100,000 person-years for males (95% CI 31.60 to 48.80) and 24.90 per 100,000 for females (95% CI 2.00 to 49.90).
  • Median exposure time and latent period were longer in environmental cohorts than in occupational cohorts: latent period 52.5 versus 38.4 years. Cumulative dose and age at diagnosis were higher in occupational cohorts: age at diagnosis 62.9 versus 52.5 years. All of these differences had p less than 0.001.
  • In the environmental cohorts, higher mesothelioma incidence was associated with female sex, erionite exposure and longer median exposure time. Lower incidence was associated with higher median cumulative exposure dose.
  • In the occupational cohorts, incidence was positively correlated with median cumulative exposure dose. Risk was higher with chrysotile and crocidolite exposure than with tremolite.
  • In the occupational cohorts, incidence rose with older age at first exposure. Incidence was inversely related to median exposure time and median age at diagnosis.
• The authors' conclusion: The authors concluded that the pooled mesothelioma incidence in environmentally exposed cohorts was as important and substantial as in occupationally exposed cohorts. They suggested the results may indicate a possible exposure threshold for developing mesothelioma.
• Limitations the authors state:
  • The study has limitations typical of ecological studies, and the occupational cohorts differed from one another (heterogeneity).
  • Most published cohorts lacked sufficient quantitative exposure data, so the number of included studies was small.
  • The data were not large enough to analyze the risk of each asbestos fiber type separately.

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: Mineral Fiber, Mesothelioma, Incidence, erionite, Cumulative Exposure, Tremolite, Asbestos Exposure, Occupational Exposure.

Related studies

• The role of environmental and occupational exposures in Turkish immigrants with fibre-related disease — P. Dumortier, A. Göcmen, et al. (2001)
• Pulmonary mineral fibers after occupational and environmental exposure to asbestos in the Russian chrysotile industry — A. Tossavainen, E. Kovalevsky, et al. (2000)
• Environmental asbestos exposure in rural Turkey and risk of lung cancer — S. Metintas, M. Metintas, et al. (2012)
• Malignant mesothelioma due to environmental exposure to asbestos: follow-up of a Turkish cohort living in a rural area — S. Metintas, M. Metintas, et al. (2002)
• Stability of mineral fibres in contact with human cell cultures. An in situ μXANES, μXRD and XRF iron mapping study — S. Pollastri, A.F. Gualtieri, et al. (2016)
• New insights into the toxicity of mineral fibres: A combined in situ synchrotron μ-XRD and HR-TEM study of chrysotile, crocidolite, and erionite fibres found in the tissues of Sprague-Dawley rats — A.F. Gualtieri, N. Bursi Gandolfi, et al. (2017)

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