Four cases of mesothelioma among Finnish anthophyllite miners

Our plain-English summary of Four cases of mesothelioma among Finnish anthophyllite miners, by A. Karjalainen, L.O. Meurman, E. Pukkala (Occupational and Environmental Medicine, 1994).

The study

• Authors: A. Karjalainen, L.O. Meurman, E. Pukkala
• Journal: Occupational and Environmental Medicine
• Published: 1994;51(3):212-5
• Cited by: 31 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Four cases of mesothelioma in a cohort of 999 Finnish anthophyllite miners and millers are described. Three deaths were due to pleural mesothelioma and one to peritoneal mesothelioma among the total of 503 male deaths up to 1991. All four patients with mesothelioma had had long term (13 to 31 years) exposure in anthophyllite mining and milling. The latency time from the onset of employment until diagnosis was 39 to 58 years. All four patients were smokers or ex-smokers and had asbestosis. In three of the cases the pulmonary fibre concentration and fibre type were analysed by transmission electron microscopy. High concentrations (270 to 1100 million fibres/g dry tissue) of anthophyllite fibres were detected. The anthophyllite fibres were thicker and had lower aspect ratios than the values reported for crocidolite fibres retained in the lungs of patients with mesothelioma.

In plain English

This report described four mesothelioma cases in the follow-up of 999 people employed three months or longer between 1936 and 1967 by a company running two anthophyllite asbestos quarries and a mill in Finland: miners, millers, and forestry, transportation and office workers. Of 593 deaths up to the end of 1991, 72 were from lung cancer, four from mesothelioma and 31 from asbestosis. Three mesotheliomas were pleural and one peritoneal. In one pleural case a sarcoma could not be completely excluded. All four patients were male smokers or ex-smokers with asbestosis who had worked 13 to 31 years in asbestos mining. Between 39 and 58 years passed from starting work to diagnosis. Lung tissue from three patients contained 270 to 1100 million fibres per gram of dry tissue, and only anthophyllite fibres were identified. Mesothelioma made up about 0.8% of male deaths. The authors noted that further mesothelioma deaths could not be ruled out, as only 30% of death certificates were based on necropsy. They concluded it seems likely that anthophyllite fibres can induce mesothelioma in humans but are less potent than crocidolite or amosite fibres.

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: Case series of mesotheliomas identified during the ongoing mortality follow-up of a worker cohort, with lung fibre analysis by electron microscopy
• Who was studied: 999 workers employed for three months or longer between 1 January 1936 and 1 July 1967 by the company running two anthophyllite quarries and a mill in Finland. They included miners, millers, forestry, transportation and office workers. They were followed to the end of 1991, and four mesothelioma cases were found among them.
• Exposure: Anthophyllite asbestos mining and milling. The four patients had 13 to 31 years of exposure at the Paakkila mine, and their occupational histories showed no other asbestos exposure.
• Main results:
  • The whole cohort had 593 deaths (503 men, 90 women) up to the end of 1991. Of these, 72 were due to lung cancer, four to mesothelioma and 31 to asbestosis.
  • Of the four mesothelioma cases, three were pleural and one was peritoneal.
  • All four patients with mesothelioma were men, were smokers or ex-smokers, and had asbestosis.
  • In the four patients, the time from starting employment to diagnosis was 39 to 58 years.
  • Lung tissue was analysed in three patients. It contained 270 to 1100 million anthophyllite fibres per gram of dry tissue.
  • In those three patients, only anthophyllite fibres were found among the 400 fibres identified per sample. Numerous talc particles were also seen.
  • In the three analysed patients, median anthophyllite fibre lengths were 3.9 to 5.1 micrometres, and 20% to 29% of fibres were longer than 10 micrometres.
  • Among men in the cohort, mesothelioma accounted for about 0.8% of all male deaths. For comparison, the authors cite 0.1% in the Finnish male population in 1982-91, from Finnish Cancer Registry statistics.
• The authors' conclusion: The authors concluded that it seems likely that anthophyllite fibres can induce mesothelioma in humans, but that they are less potent than crocidolite or amosite fibres.
• Limitations the authors state:
  • Additional mesothelioma deaths in the cohort cannot be ruled out, because only 30% of death certificates were based on necropsy.
  • Death certificates in the cohort up to the 1970s may not be as accurate as general-population data from the 1980s.
  • Proportional mortality figures from different studies may not be comparable.
  • In one pleural case (case 2), a sarcoma could not be completely excluded.
  • Exposure to fibrous tremolite was geologically possible at the mine. The authors judged it, if not nil, probably very low.

Mines named here

Asbestos mines this study is about. Each mine's page says who ran it, when it worked, and what it produced.

• Paakkila mine, Finland

All asbestos mines

Topics

The National Library of Medicine indexes this study under subjects our site covers: Anthophyllite, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Mesothelioma, Anthophyllite, Pleural Mesothelioma, Peritoneal Mesothelioma, Latency, Transmission Electron Microscopy (TEM), Aspect Ratio (Length-to-diameter ratio), Crocidolite.

Related studies

• Incidence of cancer among anthophyllite asbestos miners in Finland — L.O. Meurman, E. Pukkala, et al. (1994)
• Combined effect of asbestos exposure and tobacco smoking on Finnish anthophyllite miners and millers — L.O. Meurman, R. Kiviluoto, et al. (1979)
• Rarity of mineral fibre pleurisy among persons exposed to Finnish anthophyllite and with low risk of mesothelioma — G. Hillerdal, A. Zitting, et al. (1984)
• Anthophyllite asbestos: state of the science review — S.H. Gaffney, M. Grespin, et al. (2017)
• The distribution and characteristics of asbestos fibers in the lungs of Finnish anthophyllite mine-workers — A. Morgan, A. Holmes (1984)
• High frequency and severity of pleural changes in former workers exposed to anthophyllite associated with other contaminating amphibole asbestos in Brazil — R.F. Macedo, E.M.F.P. Cerqueira, et al. (2019)

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