Fiber levels and disease in workers from a factory predominantly using amosite

Our plain-English summary of Fiber levels and disease in workers from a factory predominantly using amosite, by A.R. Gibbs, M.J. Gardner, F.D. Pooley, et al (Environmental Health Perspectives, 1994).

The study

• Authors: A.R. Gibbs, M.J. Gardner, F.D. Pooley, D.M. Griffiths, B. Blight, J.C. Wagner
• Journal: Environmental Health Perspectives
• Published: 1994;102 Suppl 5(Suppl 5):261-3
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The Cape Boards Plant at Uxbridge produced insulation board containing amosite asbestos between 1947 and 1973 with only small amounts of chrysotile. After 1973 only amosite was used. In this study we examined lung samples from 48 workers who had been employed at the plant and who had come to autopsy. The study investigated the fiber levels against the lung pathology including amount of interstitial fibrosis and numbers of ferruginous bodies. The degree of interstitial fibrosis and number of asbestos bodies were graded and the tissues were analyzed by transmission electron microscopy and energy dispersive X-ray analysis and the fibers counted and typed. The 48 cases included 5 mesotheliomas and 14 lung cancers. The mineral analysis results were dominated by the amosite fiber levels. The amounts of chrysotile were relatively small. There were higher levels in lung cancer cases than mesotheliomas and higher levels in mesothelioma cases than those who had died from nonasbestos related diseases. Analysis of the lung tissues showed a consistent pattern of high amosite levels, which confirms the impression that amosite was the predominant form of asbestos used and also indicates that the factory had been a very dusty one.

In plain English

The authors examined autopsy lung tissue from workers at the Cape Boards Plant at Uxbridge. The plant made insulation board predominantly with amosite from 1947, with small amounts of very short chrysotile, and used only amosite after 1973. Tissue came from 49 subjects, including five pleural mesotheliomas and 14 lung cancers. Fibers were counted by electron microscopy in 43 of them. Amosite dominated, with a mean of 784.9 million fibers per gram of dried lung, against 12.1 million for chrysotile. Higher amosite levels went with higher grades of lung fibrosis and asbestos bodies. No such link was found for chrysotile, whose amounts were small. Mean amosite levels (millions of fibers per gram of dried lung) were 1433.8 in 14 lung cancer cases, 1000.7 in five mesothelioma cases and 296.9 in 24 other cases. The gap between mesothelioma and other cases reached the 5% level only on a one-tailed test. Mesothelioma and lung cancer did not differ significantly. The authors concluded that the findings corroborated amosite as the predominant fiber and supported the suggestion that the factory was dusty up to the 1960s.

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 pathological and mineralogical study of autopsy lung tissue, comparing fiber counts by transmission electron microscopy with graded lung pathology
• Who was studied: Workers from the Cape Boards Plant at Uxbridge who had come to autopsy. Pathologists and coroners provided 143 tissue blocks from 48 subjects, plus histological sections only from one more subject (49 in all). Mineral analysis was possible for 43. The subjects included 5 pleural mesotheliomas and 14 lung cancers. Dates of death are not given.
• Exposure: Work at a plant producing insulation board containing predominantly amosite since 1947, with small amounts of very short chrysotile (grades 6 or 7). Since 1973 amosite was the only asbestos used.
• Main results:
  • Among the 43 subjects with mineral analysis, mean fiber counts in millions per g of dried lung tissue were amosite 784.9 (median 106.3), crocidolite 22.5 (median 0.1) and chrysotile 12.1 (median 1.1).
  • There was a positive relationship between amosite levels and grades of fibrosis and asbestos bodies. Conclusions were unaffected by including or excluding three outlier lung cancer cases, whose amosite counts were 6476, 7853 and 3313 million per g.
  • There was no evidence that chrysotile levels affected the grades, but chrysotile amounts were small.
  • Mean amosite counts, in millions of fibers per g of dried lung tissue, were 1433.8 in the 14 lung cancer cases, 1000.7 in the 5 mesothelioma cases and 296.9 in the 24 other cases.
  • The comparison of mesothelioma with other cases was significant at the 10% level on a two-tailed test (p = 0.0941) and at the 5% level on a one-tailed test. There was no significant difference between mesothelioma and lung cancer (2-tailed p = 0.5786). The comparison of lung cancer with other cases gave a 2-tailed p of 0.1830.
  • Eleven subjects, including one mesothelioma case, had substantial amounts of crocidolite. The authors noted that this exposure could have occurred outside this factory.
  • Only three of the five mesothelioma cases had tissue suitable for assessing fibrosis, and these showed moderate to severe asbestosis.
• The authors' conclusion: The authors concluded that the tissue results corroborated factory information that amosite was the predominantly used fiber, and supported the suggestion that the factory was dusty up to the 1960s. They also judged light microscopic grading of asbestos bodies and fibrosis reasonably accurate and useful where exposure was predominantly to amosite.
• Limitations the authors state:
  • Systematic sampling of lung specimens was not possible, because the study was retrospective, specimens came from a wide geographical area, and several pathologists were involved.
  • Three lung cancer cases with very high counts made it difficult to draw firm conclusions when comparing lung cancer with the other two groups.
  • The results were not completely consistent: grade 3 fibrosis subjects had a lower mean amosite level than grade 1 to 2.5 subjects. The authors attributed this probably to sampling error.
  • In some cases fibrosis could not be assessed because adequate lung samples away from tumor had not been taken. Tissue for mineral analysis was available for only 43 cases.

Topics

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

Medical terms in this study, explained in our Lexicon: Amosite, Chrysotile, Autopsy, Pathology, Interstitial Fibrosis, Ferruginous Bodies, Asbestos Bodies, Transmission Electron Microscopy (TEM).

Related studies

• Long term radiological effects of short term exposure to amosite asbestos among factory workers — R. Ehrlich, R. Lilis, et al. (1992)
• Fiber burden and patterns of asbestos-related disease in workers with heavy mixed amosite and chrysotile exposure — A. Churg, S. Vedal (1994)
• Mortality experience of amosite asbestos factory workers: dose-response relationships 5 to 40 years after onset of short-term work exposure — H. Seidman, I.J. Selikoff, et al. (1986)
• Final results from a 90-day quantitative inhalation toxicology study evaluating the dose-response and fate in the lung and pleura of chrysotile-containing brake dust compared to TiO2, chrysotile, crocidolite or amosite asbestos: Histopathological examination, confocal microscopy and collagen quantification of the lung and pleural cavity — D.M. Bernstein, B. Toth, et al. (2021)
• Persistent effects of Libby amphibole and amosite asbestos following subchronic inhalation in rats — S.H. Gavett, C.U. Parkinson, et al. (2016)
• Correlation between fibre content of lung and disease in east London asbestos factory workers — R.M. Rudd (1989)

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