Mesotheliomas, minerals, and man-made mineral fibres

Our plain-English summary of Mesotheliomas, minerals, and man-made mineral fibres, by P.C. Elmes (Thorax, 1980).

The study

• Author: P.C. Elmes
• Journal: Thorax
• Published: 1980;35(8):561-3
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 002031).

Summary of the article

In this editorial, the author reviewed the evidence available in 1980 on which mineral fibres cause mesothelioma and noted that no clear advice could yet be given on its prevention. South African evidence had been consistent with the view that only crocidolite causes mesothelioma. No mesotheliomas had occurred in the Finnish anthophyllite mining area, although a high proportion of the population developed pleural plaques. A few more cases than expected had been reported in the Canadian chrysotile mining area, where crocidolite had been processed during the 1939-45 war and some chrysotile is contaminated with tremolite. Among British and Canadian gas mask workers, all but one of the 100 or more cases arose among those making military masks with crocidolite filters. Civilian masks contained chrysotile. Because mesothelioma has an average latent interval of about 40 years and exposure records are scanty, the author discussed lung fibre analysis by optical and electron microscopy. He noted that chrysotile fibres probably break up and dissolve in the tissue. Animal injection experiments suggested that potency relates to fibre size and shape rather than fibre type. Studies of rock, wool and glass fibre workers had not confirmed this concern. The author also described mesotheliomas in Turkey linked to erionite and tremolite. He concluded that reliance would have to be placed on animal and cell-culture tests.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This 1980 editorial by P C Elmes reported no new data. It reviewed published evidence on what causes mesothelioma. The author stated that no clear advice on preventing mesothelioma could yet be given. The editorial cited South African evidence that mesotheliomas were almost exclusively confined to crocidolite mines, mills and their environs. Among British and Canadian gas mask makers, all but one of 100 or more cases arose in those making crocidolite military respirators, not chrysotile-filter civilian masks. The one "civilian" case had not been fully investigated. No chrysotile exposure with exceptionally high mesothelioma risk had been reported, but the author wrote that doubt about its safety would remain. In rodent injection experiments, potency seemed related to fibre size and shape, not type, so long as fibres persisted in tissue. Reports from Turkey linked mesothelioma to erionite and to tremolite used in stucco and whitewash. Mesothelioma's mean latent interval is about 40 years, and most potentially hazardous fibres were recently commercialised. The author therefore concluded that, in the short term, animal and cell-culture tests, not human epidemiology, would have to be relied on.

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: Editorial (commentary reviewing previously published evidence; no original data)
• Who was studied: No study population of its own. The editorial discussed groups reported elsewhere: miners and millers in South Africa, Finland and Canada; gas mask workers in Britain and Canada; amosite insulation factory workers in the USA; villagers in Turkey.
• Exposure: Asbestos fibre types (crocidolite, chrysotile, amosite, anthophyllite, tremolite), man-made mineral fibres (rock wool, glass fibre) and other mineral fibres such as erionite
• Main results:
  • The author stated at the outset that no clear advice could yet be given on the prevention of mesotheliomas.
  • Citing South African evidence, the editorial stated that mesotheliomas had been almost exclusively confined to the crocidolite mines and mills and their environs, not the chrysotile and amosite mines.
  • Among gas mask workers in Britain and Canada, all but one of the 100 or more mesothelioma cases arose among those who made the military gas masks, which were made with crocidolite. The civilian masks had chrysotile filters, and the one 'civilian' case had not been fully investigated.
  • The editorial cited a high incidence of mesothelioma reported by Selikoff and colleagues at a dusty wartime factory making amosite insulation material.
  • No chrysotile exposures with an exceptionally high risk of mesothelioma had been reported so far, but the author wrote that doubt would remain as to the safety of chrysotile.
  • Lung fibre analyses cited by the editorial supported the view that crocidolite was the most important cause of mesothelioma in Britain, and that amosite may be the most frequent fibre in the USA.
  • In rodent experiments, fibres were injected into the pleura or peritoneum. Potency seemed related to fibre size and shape and unrelated to whether fibres were natural or synthetic, asbestos or non-asbestos, so long as they persisted in the tissue.
  • Studies of rock wool and glass fibre workers had not so far confirmed the fears raised by the animal experiments.
  • In two villages in rural Anatolia, Turkey, further study indicated that the most likely cause of mesothelioma was erionite, a fibrous zeolite, in local rock and soil. Another area of Turkey had a high incidence of lung cancer and mesothelioma related to tremolite used for stucco and whitewash.
  • The editorial stated that mesothelioma has a mean latent interval from first exposure of about 40 years.
• The authors' conclusion: The author concluded that, because most fibres in the apparently hazardous size range had only recently been exploited commercially, human epidemiology was unlikely to be a useful guide in the short term. In the author's view, reliance would have to be placed on in vivo animal tests and in vitro cell-culture tests to determine which fibres should be excluded from the air we breathe.
• Limitations the authors state:
  • The author noted that records from the period before and during the 1939-45 war were scanty, so reliable information on dust levels or even fibre type was hard to obtain.
  • The author noted that electron microscopy of lung tissue is slow and expensive, and only relatively small numbers of lungs had been fully analysed.
  • The author noted that the rate at which chrysotile fibres break up and dissolve in human lungs is not known.
  • The author noted that the dusts used in the animal injection experiments did not represent the dust to which workers were exposed.

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: Mesothelioma, Crocidolite, Anthophyllite, Pleural Plaques, Chrysotile, Tremolite, erionite.

Related studies

• Persistence of man-made mineral fibres (MMMF) and asbestos in rat lungs — B. Bellmann, H. Muhle, et al. (1987)
• Respiratory cancer incidence in Swedish construction workers exposed to man-made mineral fibres and asbestos — G. Engholm, A. Englund, et al. (1987)
• Formation of 8-hydroxydeoxyguanosine by asbestos and man made mineral fibres — P. Leanderson, P. Söderkvist, et al. (1988)
• Lung dust analysis in the assessment of past exposure of man-made mineral fibre workers — J.C. McDonald, B.W. Case, et al. (1990)
• Respiratory health effects of man-made vitreous (mineral) fibres — P. De Vuyst, P. Dumortier, et al. (1995)
• Deposition of inhaled asbestos and man-made mineral fibres in the respiratory tract — A. Morgan (1995)

Browse more research in Thorax, or return to medical research.