Asbestos Lung Burden in Necroscopic Samples from the General Population of Milan, Italy

Our plain-English summary of Asbestos Lung Burden in Necroscopic Samples from the General Population of Milan, Italy, by M. Casali, M. Carugno, A. Cattaneo, et al (The Annals of Occupational Hygiene, 2015).

The study

• Authors: M. Casali, M. Carugno, A. Cattaneo, D. Consonni, C. Mensi, U. Genovese, D.M. Cavallo, A. Somigliana, A.C. Pesatori
• Journal: The Annals of Occupational Hygiene
• Published: 2015;59(7):909-21
• Cited by: 23 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The present study analysed the asbestos lung burden in necroscopic samples from 55 subjects free from asbestos-related diseases, collected between 2009 and 2011 in Milan, Italy. Multiple lung samples were analysed by light microscopy (asbestos bodies, AB) and EDXA-scanning electron microscopy (asbestos fibres and other inorganic fibres). Asbestos fibres were detected in 35 (63.6%) subjects, with a higher frequency for amphiboles than for chrysotile. Commercial (CA) and non-commercial amphiboles (NCA) were found in roughly similar frequencies. The estimated median value was 0.11 million fibres per gram of dry lung tissue (mf g(-1)) for all asbestos, 0.09 mf g(-1) for amphiboles. In 44 (80.0%) subjects no chrysotile fibres were detected. A negative relationship between asbestos mass-weighted fibre count and year of birth (and a corresponding positive increase with age) was observed for amphiboles [-4.15%, 95% confidence interval (CI) = -5.89 to -2.37], talc (-2.12%, 95% CI = -3.94 to -0.28), and Ti-rich fibres (-3.10%, 95% CI = -5.54 to -0.60), but not for chrysotile (-2.84%, 95% CI = -7.69 to 2.27). Residential district, birthplace, and smoking habit did not affect the lung burden of asbestos or inorganic fibres. Females showed higher burden only for amphiboles (0.12 versus 0.03 mf g(-1) in males, P = 0.07) and talc fibres (0.14 versus 0 mf g(-1) in males, P = 0.03). Chrysotile fibres were shorter and thinner than amphibole fibres and NCA fibres were thicker than CA ones. The AB prevalence was 16.4% (nine subjects) with concentrations ranging from 10 to 110 AB g(-1) dry, well below the 1000 AB g(-1) threshold for establishing occupational exposure. No AB were found in subjects younger than 30 years. Our study demonstrated detectable levels of asbestos fibres in a sample taken from the general population. The significant increase with age confirmed that amphibole fibres are the most representative of cumulative exposure.

© The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

In plain English

This autopsy study measured asbestos in the lungs of 55 people from the general population of Milan, Italy (30 males and 25 females). Autopsies took place between January 2009 and August 2011. People diagnosed with an asbestos-related disease were excluded. Electron microscopy found asbestos fibres in 35 people (63.6%). Amphibole fibres were found in 58.2% of people and chrysotile in 20%. The median for all asbestos was 0.11 million fibres per gram of dry lung. Three people (5.5%) had more than 1.00 million amphibole fibres longer than 1 µm per gram of dry lung, a threshold used to suggest work exposure. Work exposure was considered likely for one of them, a former automotive industry worker. Amphibole counts were lower in people born later; no such link was found for chrysotile. Asbestos bodies appeared in 16.4% of people (none under 30), at 10 to 110 per gram of dry lung, well below a threshold of 1000 per gram of dry lung for likely workplace exposure. The authors noted detailed work histories could not be collected and cross-laboratory comparisons are problematic.

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 autopsy (necroscopic) study of lung tissue fibre content, with statistical analysis of associations with year of birth, sex, residence, birthplace and smoking
• Who was studied: 55 deceased residents of Milan, Italy (30 males, 25 females; 15 aged 30 or under, 21 aged 30 to 59, 19 aged 60 or over) autopsied between January 2009 and August 2011. Anyone with an ante-mortem or post-mortem diagnosis of an asbestos-related disease (pleural adhesions, lung fibrosis, pleural plaques, mesothelioma, lung cancer) was excluded.
• Exposure: Lung burden of asbestos in a general urban population, measured as asbestos bodies (light microscopy) and fibres longer than 1 µm (scanning electron microscopy with X-ray analysis). Fibres were classed as chrysotile, commercial amphiboles (amosite and crocidolite), non-commercial amphiboles (only tremolite was observed), talc, titanium-containing fibres and other inorganic fibres.
• Main results:
  • Asbestos fibres were detected in 35 of 55 subjects (63.6%); none were found in 20.
  • Chrysotile was detected in 20% of all subjects and amphiboles in 58.2%.
  • The median asbestos lung burden in the whole group was 0.11 million fibres per gram of dry lung tissue.
  • Three subjects (5.5%) had an amphibole burden above the threshold used to define occupational exposure, 1.00 mf per gram for fibres longer than 1 µm. Occupational exposure was considered likely for only one of them, a former automotive industry worker.
  • The highest asbestos burden was 2.00 mf per gram (100% chrysotile). The highest amphibole burden was 1.7 mf per gram.
  • Asbestos fibre count fell by 3.66% per one-year later year of birth (95% CI −5.50 to −1.79, P less than 0.001), meaning counts rose with age.
  • For amphiboles the change was −4.15% per later birth year (95% CI −5.89 to −2.37). For chrysotile it was −2.84% (95% CI −7.69 to 2.27, P = 0.3), and the authors reported no association with year of birth for chrysotile.
  • Median amphibole burden was 0.12 mf per gram in females versus 0.03 in males (P = 0.07). Median talc burden was 0.14 in females versus 0 in males (P = 0.03).
  • Asbestos burden did not differ by residential district, birthplace or smoking habit.
  • Typical asbestos bodies were found in 16.4% of subjects (4 males, 5 females), and in no one younger than 30. Ranges were 10 to 110 per gram of dry lung tissue in males and 10 to 30 in females. This was well below the 1000 per gram threshold proposed to identify a high probability of workplace exposure.
  • Chrysotile fibres were shorter and thinner than amphibole fibres.
• The authors' conclusion: The authors concluded that their results, obtained 20 years after Italy's asbestos ban, are intermediate evidence during a period of decreasing environmental exposure, and that reference levels should be updated in future. They considered amphiboles the only reliable index of cumulative dose.
• Limitations the authors state:
  • A detailed work history could not be collected, so it could not be established whether high burdens came from work. Only some job information was gathered from relatives.
  • Comparing fibre burdens between studies may be problematic because laboratories do not use standardised analysis and post-mortem sampling methods.
  • Scanning electron microscopy may underestimate chrysotile compared with transmission electron microscopy.
  • For very thin fibres, amosite and crocidolite could not be told apart, so they were reported together as commercial amphiboles.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Bodies, Scanning Electron Microscopy (SEM), Amphibole Group, Chrysotile, confidence interval, Talc, Habit, Occupational Exposure.

Related studies

• Fiber size and number in workers exposed to processed chrysotile asbestos, chrysotile miners, and the general population — A. Churg, B. Wiggs (1986)
• Inorganic Fiber Lung Burden in Subjects with Occupational and/or Anthropogenic Environmental Asbestos Exposure in Broni (Pavia, Northern Italy): An SEM-EDS Study on Autoptic Samples — S.D. Visonà, S. Capella, et al. (2021)
• Is Mesothelioma Unrelated to the Lung Asbestos Burden? Comment on Visonà et al. Inorganic Fiber Lung Burden in Subjects with Occupational and/or Anthropogenic Environmental Asbestos Exposure in Broni (Pavia, Northern Italy): An SEM-EDS Study on Autoptic Samples. Int. J. Environ. Res. Public Health 2021, 18, 2053 — D. Mirabelli, A. Angelini, et al. (2021)
• Reply to Mirabelli et al. Is Mesothelioma Unrelated to the Lung Asbestos Burden? Comment on "Visonà et al. Inorganic Fiber Lung Burden in Subjects with Occupational and/or Anthropogenic Environmental Asbestos Exposure in Broni (Pavia, Northern Italy): An SEM-EDS Study on Autoptic Samples. Int. J. Environ. Res. Public Health 2021, 18, 2053" — S.D. Visonà, S. Capella, et al. (2021)
• Relation of occupational exposure to respiratory symptoms and asthma in a general population sample: self-reported versus interview-based exposure data — P.S. Bakke, R. Hanoa, et al. (2001)
• Peritoneal mesothelioma and asbestos exposure: a population-based case-control study in Lombardy, Italy — D. Consonni, C. Calvi, et al. (2019)

Browse more research in The Annals of Occupational Hygiene, or return to medical research.