Pleural plaques and asbestos: further observations on endemic and other nonoccupational asbestosis

Our plain-English summary of Pleural plaques and asbestos: further observations on endemic and other nonoccupational asbestosis, by R. Kiviluoto (Annals of the New York Academy of Sciences, 1965).

The study

• Author: R. Kiviluoto
• Journal: Annals of the New York Academy of Sciences
• Published: 1965;132(1):235-9
• Cited by: 38 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. 002505).

Summary of the article

The author reported further observations on pleural plaques in people in Finland who did not work with asbestos. Anthophyllite asbestos had been mined there since 1918. Several hundred cases of pleural calcification had earlier been found in non-miners near two open asbestos mines, termed 'endemic asbestosis'. Slight pulmonary fibrosis was visible on X-ray in about 14% of 150 such cases. Heart volume, measured on X-ray in 130 plaque cases, was 18% greater than in controls of similar age taken from the X-ray file. In 38 plaque cases and 23 controls, diffusing capacity was reduced in nine and two respectively, a difference that was not statistically significant. Mean vital capacity was 3600 versus 4000, which was significant. The author considered positive conclusions impossible. Of 216 histologically proven lung carcinomas in Northern Karelia in 1958-61, all in men, the cases were not more frequent around the mines. Twenty-one of them also had endemic asbestosis. One pleural mesothelioma, with lifelong environmental exposure, was recorded in 1959-62. Among 35,000 routine chest X-rays in 1963-64, 77 plaque cases were found, and 68 were questioned about exposure. Bricklayers had dyspnea and definite fibrosis. Cases without detectable dust exposure had slight or no lung changes. The author concluded that plaques develop slowly, and that even slight, brief exposure may cause pleural changes decades later. Plaques, though not pathognomonic, were judged useful for industrial hygiene and epidemiology.

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 article reported several sets of observations by the author on pleural plaques in people in Finland who did not work in asbestos mining. Anthophyllite has been mined in Finland since 1918. The author called plaque cases found near two open asbestos mines "endemic asbestosis". Slight lung fibrosis was seen on X-ray in about 14 per cent of 150 such cases. In 38 plaque cases compared with 23 controls, mean vital capacity was lower (3600 versus 4000), and this difference was statistically significant. Reduced diffusing capacity (9 plaque cases, 2 controls) was not statistically significant, and the author judged positive conclusions impossible. Among 216 lung carcinoma cases in Northern Karelia in 1958-61, cases were not more frequent around the two mines. The Central Hospital paid special attention to possible pleural mesothelioma during 1959-62, and only one case was recorded there. Among 35,000 routine chest X-rays in Tampere in 1963-64, 77 plaque cases were found. The author concluded that plaques develop very slowly and that even very slight exposure over a short period may cause pleural changes years or decades later.

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: Report of clinical and X-ray observations. It includes comparisons of plaque cases with controls, a hospital lung carcinoma case series, and individual case histories.
• Who was studied: People in Finland with pleural plaques or calcification who were not employed in mining, living near two open asbestos mines. The groups were: 150 endemic cases; 130 cases for heart volume measurement; 38 plaque cases and 23 controls for lung function tests; 216 lung carcinoma cases at the Central Hospital of Northern Karelia, 1958-61; and 77 plaque cases found at Tampere Central Hospital, 1963-64.
• Exposure: Nonoccupational (environmental) exposure to asbestos near two open asbestos mines in Finland, where anthophyllite has been mined since 1918; tremolite-asbestos is also described in Northern Karelia. Among the Tampere cases, the exposures included occupational and intermittent exposure to mixed dusts containing asbestos (for example, bricklayers and building workmen).
• Main results:
  • Slight pulmonary fibrosis was detectable on X-ray in about 14 per cent of 150 endemic cases.
  • Heart volumes of the plaque group (130 cases) were 18 per cent greater than those of the controls.
  • Diffusing capacity was decreased in 9 of the 38 plaque cases and 2 of the 23 controls; this difference was not statistically significant.
  • Mean vital capacity was 3600 in the plaque cases and 4000 in the controls (units not stated). The reduction was statistically significant at the 95 per cent level (F = 4.76).
  • The 216 lung carcinoma cases in Northern Karelia were not more frequent around the two asbestos mines. Endemic asbestosis and lung carcinoma occurred together in 21 cases.
  • The Central Hospital paid special attention to possible pleural mesothelioma during 1959-62, and only one case was recorded there. That person had lifelong environmental asbestos exposure.
  • 77 cases of pleural plaques were found among 35,000 routine chest X-ray examinations at Tampere in 1963-64.
  • Among the Tampere cases, bricklayers had various degrees of shortness of breath and definite pulmonary fibrosis on X-ray. Cases with no detectable dust exposure had slight or absent lung changes.
  • In one plaque case whose father had been exposed to mixed dusts 50 years earlier, all three of the patient's sisters had bilateral pleural changes. The husband had no changes.
• The authors' conclusion: The author concluded that plaques develop very slowly and that even very slight exposure over a short period may cause pleural changes many years or decades later. The author also stated that lung and pleural tumors are rare compared with plaques in environmentally exposed people, and that the lung carcinoma distribution counted against a causal conclusion.
• Limitations the authors state:
  • Reduced vital capacity can occur in many diseases, so positive conclusions about lung function were not possible.
  • Judging the degree of fibrosis in living patients, and its link to asbestos dust, is complex and difficult.
  • Asbestos exposure is often very hard to discover from case histories.
  • Asbestos is hard to find in tissue sections of ordinary thickness.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Plaques, Endemic, Anthophyllite, Pleural Calcification, Pulmonary Fibrosis, Diffusing Capacity (DLCO), Carcinoma, Pleural Mesothelioma.

Related studies

• Asbestos-related cancer risk in patients with asbestosis or pleural plaques — J. Ameille, P. Brochard, et al. (2011)
• Inter-reader agreement in HRCT detection of pleural plaques and asbestosis in participants with previous occupational exposure to asbestos — F. Laurent, C. Paris, et al. (2014)
• Pleural plaques in asbestosis: effect of Candida albicans — K.C. Saxena, L. Srivastava, et al. (1982)
• Further observations on the ultrastructure and chemistry of the formation of asbestos bodies — J.M. Davis (1970)
• Further observations on the short-term retention and clearance of asbestos by rats, using UICC reference samples — A.P. Middleton, S.T. Beckett, et al. (1979)
• Pleural plaques and exposure to mineral fibres in a male urban necropsy population — A. Karjalainen, P.J. Karhunen, et al. (1994)

Browse more research in Annals of the New York Academy of Sciences, or return to medical research.