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

Our plain-English summary of 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, by S.D. Visonà, S. Capella, S. Bodini, et al (International Journal of Environmental Research and Public Health, 2021).

The study

• Authors: S.D. Visonà, S. Capella, S. Bodini, P. Borrelli, S. Villani, E. Crespi, A. Frontini, C. Colosio, E. Belluso
• Journal: International Journal of Environmental Research and Public Health
• Published: 2021;18(4)
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Increased mortality due to malignant mesothelioma has been demonstrated by several epidemiologic studies in the area around Broni (a small town in Lombardy, northern Italy), where a factory producing asbestos cement was active between 1932 and 1993. Until now, the inorganic fiber burden in lungs has not been investigated in this population. The aim of this study is to assess the lung fiber burden in 72 individuals with previous occupational and/or anthropogenic environmental exposure to asbestos during the activity of an important asbestos cement factory. Inorganic fiber lung burden was assessed in autoptic samples taken from individuals deceased from asbestos-related diseases using a scanning electron microscope equipped with an energy-dispersive spectrometer. Significant differences in the detected amount of asbestos were pointed out among the three types of exposure. In most lung samples taken from patients who died of mesothelioma, very little asbestos (or, in some cases, no fibers) was found. Such subjects showed a significantly lower median amount of asbestos as compared to asbestosis. Almost no chrysotile was detected in the examined samples. Overall, crocidolite was the most represented asbestos, followed by amosite, tremolite/actinolite asbestos, and anthophyllite asbestos. There were significant differences in the amount of crocidolite and amosite fibers according to the kind of exposure. Overall, these findings provide novel insights into the link between asbestos exposure and mesothelioma, as well as the different impacts of the various types of asbestos on human health in relation to their different biopersistences in the lung microenvironment.

In plain English

This study used scanning electron microscopy to measure mineral fibers in autopsy lung samples from 72 people in Broni, northern Italy, where an asbestos cement factory operated from 1932 to 1993. All had died of asbestos-related disease: 59 of pleural mesothelioma, 13 of asbestosis. Twenty had only occupational exposure, 26 only environmental exposure, and 26 both. Environmental exposure meant living near the plant, sometimes with household exposure. Asbestos fiber levels did not differ significantly between these groups. Asbestos bodies (coated fibers) were significantly higher with both exposures than with environmental exposure alone. Those who died of mesothelioma had a significantly lower median asbestos level (11,320.0 fibers per gram of dry lung) than those who died of asbestosis (297,895.0), with significantly less crocidolite and amosite. Crocidolite and amosite made up most of the asbestos. Fibers classed as chrysotile or asbestiform antigorite, which the method could not separate, appeared in only one sample. The authors concluded that mesothelioma risk is not related to asbestos dose, unlike asbestosis. They noted that little tissue was examined and thin chrysotile fibers might have been missed.

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: Retrospective cohort design. Lung tissue taken at forensic autopsy was analyzed by scanning electron microscopy with energy-dispersive spectrometry (SEM-EDS). A subsample was drawn by stratified random sampling by type of exposure.
• Who was studied: 72 people selected from 188 eligible people who had lived in Broni (Pavia province, northern Italy) and died of mesothelioma or asbestosis. All were in the records of the Forensic Medicine Department of the University of Pavia from 2000 to 2018. 62 (86.1%) were male. 59 died of pleural mesothelioma and 13 of asbestosis and its complications.
• Exposure: Asbestos from an asbestos cement factory in Broni (1932–1993) that used mainly chrysotile and crocidolite, with smaller amounts of amosite. Exposure was classed as occupational only (20 people, 27.8%), anthropogenic environmental only (26 people, 36.1%), or both (26 people, 36.1%). Environmental exposure meant living in an area with air-dispersed asbestos from the plant. In six cases it was both residential and household; the article does not say which exposure group these six were in.
• Main results:
  • Asbestos fiber concentrations did not differ significantly across the three exposure groups. Medians were 22,530.5 ff/gdw (occupational only), 20,336.9 (environmental only) and 24,199.7 (both); Kruskal–Wallis p = 0.192.
  • Asbestos bodies were significantly higher in people with both exposures than in those exposed only environmentally (p = 0.001). Medians were 34,002.4 versus 0.0 per gram of dry lung.
  • People who died of mesothelioma (n = 59) had a significantly lower median asbestos concentration (11,320.0 ff/gdw) than people who died of other causes, that is, asbestosis (n = 13; 297,895.0 ff/gdw); p < 0.001.
  • Crocidolite and amosite were significantly lower in mesothelioma cases than in non-mesothelioma cases. Anthophyllite asbestos and tremolite/actinolite asbestos did not differ significantly by cause of death.
  • Across all samples, crocidolite made up 51% of the asbestos found, amosite 46%, tremolite/actinolite asbestos 3.3% and anthophyllite asbestos 0.9%.
  • Fibers classed as chrysotile/asbestiform antigorite (a group the method could not separate) were found, in extremely low quantity, in only one sample.
  • In 45 of 59 mesothelioma cases (76.3%), asbestos fiber levels were well below the threshold considered demonstrative of occupational exposure.
  • In 19.4% of all lung samples, neither fibers nor asbestos bodies were observed. Of these, eight had only environmental exposure, three only occupational and three both; most died of mesothelioma.
  • Among mesothelioma cases, total asbestos and the mix of asbestos types did not differ significantly between epithelial, sarcomatoid and biphasic types.
• The authors' conclusion: The authors concluded that their results confirm that mesothelioma risk is not related to asbestos dose, as opposed to asbestosis, which they described as clearly dose-dependent. They called for more research on how long asbestos persists in the lung and on individual differences in biological response.
• Limitations the authors state:
  • Only a limited amount of lung tissue was analyzed. Finding no asbestos does not mean the lungs were free of it.
  • The technique could not tell chrysotile from asbestiform antigorite, or tremolite asbestos from actinolite asbestos, so these were grouped together.
  • Chrysotile fibers might have been too thin to detect with the microscope used, whose resolution was limited to 0.2 µm.

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: Asbestos Exposure, Malignant Mesothelioma, Asbestos-Cement, Fiber Burden, Environmental Exposure, Mesothelioma, Chrysotile, Crocidolite.

Related studies

• 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)
• 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)
• Evaluation of Deposition and Clearance of Asbestos (Detected by SEM-EDS) in Lungs of Deceased Subjects Environmentally and/or Occupationally Exposed in Broni (Pavia, Northern Italy) — S.D. Visonà, S. Capella, et al. (2021)
• Asbestos burden in lungs of non-occupationally exposed women from Broni (Pavia, Italy): a postmortem SEM-EDS study — S.D. Visonà, S. Capella, et al. (2023)
• Respirable inorganic fibers dispersed in air and settled in human lung samples: Assessment of their nature, source, and concentration in a NW Italy large city — S. Capella, D. Bellis, et al. (2020)
• Impact of asbestos on public health: a retrospective study on a series of subjects with occupational and non-occupational exposure to asbestos during the activity of Fibronit plant (Broni, Italy) — S.D. Visonà, S. Villani, et al. (2018)

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