Asbestos lung burden and asbestosis after occupational and environmental exposure in an asbestos cement manufacturing area: a necropsy study

Our plain-English summary of Asbestos lung burden and asbestosis after occupational and environmental exposure in an asbestos cement manufacturing area: a necropsy study, by C. Magnani, F. Mollo, L. Paoletti, et al (Occupational and Environmental Medicine, 1998).

The study

• Authors: C. Magnani, F. Mollo, L. Paoletti, D. Bellis, P. Bernardi, P. Betta, M. Botta, M. Falchi, C. Ivaldi, M. Pavesi
• Journal: Occupational and Environmental Medicine
• Published: 1998;55(12):840-6
• Cited by: 26 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objective: The largest Italian asbestos cement factory had been active in Casale Monferrato until 1986: in previous studies a substantial increase in the incidence of pleural mesothelioma was found among residents without occupational exposure to asbestos. To estimate exposure to asbestos in the population, this study evaluated the presence of histological asbestosis and the lung burden of asbestos fibres (AFs) and asbestos bodies (ABs).

Methods: The study comprises the consecutive series of necropsies performed at the Hospital of Casale Monferrato between 1985 and 1988. A sample of lung parenchima was collected and stored for 48 out of 55 necropsies. The AF concentration was measured with a TEM electron microscope with x ray mineralogical analysis. The ABs were counted and fibrosis evaluated by optical microscopy. The nearest relative of each subject was interviewed on occupational and residential history. Mineralogical and histological analyses and interviews were conducted in 1993-4.

Results: Statistical analyses included 41 subjects with AF, AB count, and interview. Subjects without occupational exposure who ever lived in Casale Monferrato had an average concentration of 1500 AB/g dried weight (gdw); Seven of 18 presented with asbestosis or small airway lung disease (SAL). G2 asbestosis was diagnosed in two women with no occupational asbestos exposure. One of them had been teaching at a school close to the factory for 12 years. Ten subjects had experienced occupational asbestos exposure, seven in asbestos cement production: mean concentrations were 1.032 x 10(6) AF/gdw and 96,280 AB/gdw. Eight of the 10 had asbestosis or SAL.

Conclusion: The high concentration of ABs and the new finding of environmental asbestosis confirm that high asbestos concentration was common in the proximity of the factory. Subjects not occupationally exposed and ever living in Casale Monferrato tended to have higher AB concentration than subjects never living in the town (difference not significant). The concentrations of ABs and AFs were higher than those found in other studies on nonoccupationally exposed subjects.

In plain English

This necropsy (autopsy) study examined lung tissue from the consecutive autopsies done at the General Hospital of Casale Monferrato, Italy, home to a large asbestos cement factory, from July 1985 to July 1988. Of 55 autopsies, 48 had a lung sample and 41 people were analysed. Ten people had occupational asbestos exposure, seven of them in asbestos cement production. Their lung asbestos fibre and asbestos body levels were significantly higher than in the 31 people without such exposure. Seven of the ten had asbestosis and one had small airway lesions (SAL). Among the 31 without occupational exposure, two had asbestosis and nine had SAL. Both of these asbestosis cases were women who had lived in Casale Monferrato. One had taught for 12 years at a school 250 m from the factory. Non-occupationally exposed people who had ever lived in the town had higher average asbestos body counts than those who never had, but the difference was not statistically significant. The authors concluded this confirmed high environmental asbestos exposure in the area linked to asbestos cement production. They noted small numbers and only one lung sample per person.

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: Necropsy (autopsy) study of a consecutive, unselected series of hospital autopsies, with lung fibre and asbestos body counts, lung tissue examination, and interviews with relatives
• Who was studied: 55 autopsies at the General Hospital of Casale Monferrato, Italy, July 1985 to July 1988. A lung sample was available for 48, and 41 people were included in the statistical analyses. Nearest relatives were interviewed in 1994.
• Exposure: Occupational asbestos exposure, defined as any job in asbestos cement production or work in the construction industry. Residence in Casale Monferrato, where the asbestos cement factory operated, among people without occupational exposure.
• Main results:
  • The 10 occupationally exposed subjects (7 in asbestos cement production) had a mean of 1.032 x 10^6 total asbestos fibres per gram dry weight (gdw). The 31 subjects without occupational exposure had a mean of 0.024 x 10^6 fibres/gdw.
  • Mean asbestos bodies were 96285 AB/gdw in the 10 occupationally exposed subjects and 1064 AB/gdw in the 31 non-exposed subjects.
  • The exposed and non-exposed groups differed significantly for asbestos fibres (p less than 0.005), crocidolite (p=0.02), asbestos bodies (p=0.006) and frequency of asbestosis and SAL (p less than 0.005).
  • Among the 10 occupationally exposed subjects, asbestosis was found in 7 and SAL in 1.
  • Among the 31 subjects without occupational exposure, asbestosis was found in 2 and SAL in 9.
  • Among non-occupationally exposed subjects, 5 SAL cases and 2 G2 asbestosis cases occurred in the 18 who ever lived in Casale Monferrato. The 13 who never lived there had 4 SAL cases and no asbestosis.
  • The two non-occupationally exposed women with asbestosis had each been in Casale Monferrato for over 50 years. One had worked as a school teacher for 12 years (1958 to 1969) at a school 250 m from the factory. No information was available for the other. Both had 800 AB/gdw.
  • Among subjects without occupational exposure, mean asbestos bodies were 1466 AB/gdw (SD 2244) in the 18 who ever lived in Casale Monferrato and 500 AB/gdw (SD 576) in the 13 who never did. The difference was not significant.
  • The authors used a cut-off of 1000 AB/gdw, which they describe as considered indicative of occupational exposure. It was exceeded by 8 of 10 occupationally exposed subjects (6 of 7 asbestos cement employees), by 5 of 18 non-occupationally exposed subjects living in Casale, and by 1 of 13 non-occupationally exposed subjects never living in Casale.
  • Of the 392 fibres detected in the study, 4% were chrysotile and 96% amphibole.
  • Average fibre length was 16.3 in occupationally exposed subjects and 11.7 in subjects without occupational exposure (p less than 0.0001).
  • One man was excluded from the analyses as an outlier: a farmer with no reported occupational exposure whose two sons worked in asbestos cement production. His lung contained 532 000 crocidolite fibres/gdw and 770 ABs/gdw. He had SAL and died from pleural mesothelioma.
• The authors' conclusion: The authors concluded that the two cases of histological asbestosis, the high prevalence of SAL and the high asbestos body concentrations among non-occupationally exposed residents confirm a high prevalence of environmental asbestos exposure in the area, related to asbestos cement production.
• Limitations the authors state:
  • Only one lung sample per person was available, and the location in the lung was not recorded.
  • The study was based on limited numbers.
  • Analyses by smaller areas of the town and by distance of home from the factory gave inconsistent results because of small numbers and were not presented.
  • Subjects with no fibres or asbestos bodies detected were counted as 0, which underestimates the means.

Topics

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

Medical terms in this study, explained in our Lexicon: Environmental Exposure, Asbestos-Cement, Autopsy, Casale Monferrato, Pleural Mesothelioma, Occupational Exposure, Asbestos Bodies, Fibrosis.

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