Pleural fibrocalcific plaques and asbestos exposure

Our plain-English summary of Pleural fibrocalcific plaques and asbestos exposure, by L.O. Meurman (Environmental Research, 1968).

The study

• Author: L.O. Meurman
• Journal: Environmental Research
• Published: 1968;2(1):30-46
• Type of article: Review
• Cited by: 25 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 002707).

Summary of the article

This article reviewed published evidence on the association between calcified (fibrocalcific) pleural plaques and asbestos exposure. The author noted that pleural calcification visible on X-ray was relatively rare, at about 0.2% in large radiological series, and that it usually followed haemothorax, pleurisy or empyema. Studies cited included bilateral calcification in 6.3% of New York talc miners (Siegal, 1943), 5% of Dresden asbestos workers (Jacob and Bohlig, 1955), and 11 of 31 Danish insulation workers (Frost, 1956). Selikoff (1965) found 150 cases among 1,117 New York insulators, 145 of them in the 393 with more than 20 years' exposure. Other reports showed that plaques and asbestosis often did not occur together. In the Finnish anthophyllite mining area, calcification was found in 9% of adults in one commune and 6.5% in a neighbouring one, compared with about 0.5 per thousand elsewhere in Finland, including among people who had not worked at the mine or mill. Asbestos dust was found in snow up to 27 km from the mine, and asbestos stones used locally in fireplaces and saunas were suggested as a source. A Malmö autopsy study found asbestos bodies in 18 of 34 mesothelioma cases and in 12 controls. The author concluded that asbestos plays an essential part in plaque formation, but that another, as yet unknown factor, possibly environmental, also appears to be involved.

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 1968 paper was a review of the literature on calcified plaques of the pleura (the lining of the chest), not a new study. It covered asbestos and talc workers, insulation workers, mass X-ray surveys and people near asbestos deposits. The review included the author's earlier study of 438 consecutive Finnish autopsies, which found pleural plaques in 39.3%. Of 229 of these autopsies whose lungs were checked for asbestos bodies, 124 had plaques; asbestos bodies were found in 79% of those 124 and not demonstrated in the other 21%. In rural Czechoslovakia one investigator traced no asbestos exposure in people with plaques and another suggested only uncertain tremolite talc exposure; near Leipzig, only four of 33 cases had a history of occupational exposure to asbestos or talc. The author concluded that, besides asbestos dust, some unknown contributing factor seemed to be involved in plaque formation, and that how plaques form was still unclear. The author cautioned that a role for asbestos in such cases could not be ruled out until the lungs were examined for asbestos fibers or bodies.

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: Review of recent literature on calcified pleural plaques, including the author's own earlier autopsy study
• Who was studied: Published series reviewed: talc and asbestos miners and workers, insulation workers, populations screened in mass X-ray surveys (Finland, Czechoslovakia, Germany, Bulgaria and other countries), autopsy series from London and Finland, and people living near asbestos mines
• Exposure: Occupational and non-occupational (environmental) exposure to asbestos, both serpentine and amphibole: chrysotile (Canadian mines), crocidolite (South African mines), anthophyllite (Finnish mines), and tremolite talc dust
• Main results:
  • In the author's earlier Finnish study of 438 consecutive autopsy cases at three central hospitals, pleural plaques were found in 39.3% of the whole series, with a range of 13 to 57% between hospitals
  • In that Finnish study, lungs were examined for asbestos bodies only at the two hospitals where plaques were most often seen, in 229 cases. Plaques were seen in 124 of these 229, and asbestos bodies were found in the lungs in 79% of those 124 plaque cases, mostly in small amounts
  • In 21% of the Finnish plaque cases whose lungs were examined, asbestos was not demonstrated in the lungs. In the London autopsy series, asbestos was found in the lungs in all cases with plaques
  • In the London Hospital autopsy series (Hourihane et al., 1966), plaque-like pleural thickenings were seen in 4.2-11.2% of cases, all of which had small amounts of asbestos bodies in the lung
  • In the London series almost half of the cases with plaques showed asbestosis. In the Finnish series, plaques were not associated with fibrosis or other chronic lung disease
  • In mass X-ray surveys near Leipzig (Neef, 1963), 33 typical cases of bilateral plaque-like pleural calcification were found among 111,069 subjects
  • Of the Leipzig cases (Neef, 1963), only four had a history of occupational exposure to asbestos or talc
  • In mass surveys of rural populations in two Czechoslovak districts, bilateral plaque-like pleural calcifications were found. Hromek (1962) could trace no asbestos exposure, and Marsová (1964) suggested only uncertain exposure to tremolite talc
  • In Finland (Kiviluoto, 1960), calcifications were found on mass X-ray surveys in 9% of the adult population of a commune (Tuusniemi) with an anthophyllite asbestos mine and mill, and in 6.5% in the neighboring commune
  • In a Swedish-Finnish autopsy study from Malmö in which the author took part (Hägerstrand et al., 1968), asbestos bodies were found in the lungs in 18 of the cases of diffuse mesothelioma (6 in relative abundance) and in 12 cases of an age- and sex-matched control series. This was reported as giving no definite proof of an association
• The authors' conclusion: The author concluded that, in addition to asbestos dust exposure, some unknown internal or external contributing factor seemed to be responsible for pleural plaque formation, and that how plaques develop was still obscure
• Limitations the authors state:
  • The author cautioned that, in the series reporting plaques without asbestos exposure, a role for asbestos could not be definitely ruled out until the lungs had been examined histologically for asbestos fibers or bodies

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis, Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Pleural Plaques, Pleural Calcification, Pleurisy, Empyema, Bilateral, Talc, Insulator.

Related studies

• Pleural plaques: only an imagiologic finding? — P. Almeida, A. Araújo (2019)
• Pleural plaques: a signpost of asbestos dust inhalation — E.N. Sargent, G. Jacobson, et al. (1977)
• Multiple pleural plaques. II — H.C. Anton (1968)
• Calcified interlobar pleural plaques: visceral pleural involvement due to asbestos — E.N. Sargent, J.S. Felton, et al. (1981)
• Calcified plaques on mediastinal pleural reflections associated with asbestos dust exposure: four case reports — A. Solomon, G.K. Sluis-Cremer, et al. (1984)
• Asbestos-related pleural plaques — C.K. Lim, Y.F. Chen (2014)

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