Clinical observations following asbestos exposure

Our plain-English summary of Clinical observations following asbestos exposure, by A.L. Frank (Environmental Health Perspectives, 1980).

The study

• Author: A.L. Frank
• Journal: Environmental Health Perspectives
• Published: 1980;34:27-30
• Cited by: 3 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. 002036).

Abstract

There is a spectrum of clinical entities following occupational exposure to asbestos. Methods of evaluation for these problems are reviewed. Nonmalignant clinical conditions include asbestos warts, asbestos bodies, parenchymal fibrosis (asbestosis), pleural fibrosis and calcification, and benign asbestotic pleural effusion. Asbestosis, though a benign process, is a significant cause of death. Malignant conditions associated with asbestos exposure include lung cancer, accounting for about 20% of all deaths among insulation workers and significantly related to cigarette smoking. The lung cancers tend to occur more frequently in the lower lobes and are more peripheral. Pleural and peritoneal mesothelioma and some excesses in gastrointestinal cancers are found with asbestos exposure, although these are not related to cigarette smoking. Increased rates of malignancy first become significant after 20 years from onset of exposure and are also related to duration of exposure. Difficulties with the use of death certificate data are reviewed.

In plain English

This 1980 article is a narrative review, not a new study. The author described illnesses linked to occupational asbestos exposure and how they are evaluated. Its main figures came from Selikoff and colleagues' study of 17,800 asbestos insulation workers in the United States and Canada, 1967 to 1976. In that group, 2,271 deaths occurred against about 1,661 expected. After review of autopsy, surgical and clinical records, 486 deaths were from lung cancer, against about 106 expected, and 175 were from mesothelioma. Death certificates alone were misleading. They recorded 49 pancreatic cancer deaths, but further review found only 23, close to the 17.5 expected. They also undercounted asbestosis by about one-half. The author stated that mesothelioma is not related to cigarette smoking. The author also cited other researchers' reports of mesothelioma in workers who did not handle asbestos directly and in household contacts. The author concluded that further investigation is needed to define the risk from long-term, low-level exposure in the general population.

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: Narrative review (clinical overview) with no new data of its own. Its tables are taken from Selikoff et al.'s mortality study of insulation workers.
• Who was studied: No population of its own. The main data reviewed come from Selikoff et al.'s cohort of 17,800 asbestos insulation workers in the United States and Canada, followed January 1, 1967 to December 31, 1976 (166,853 man-years of observation).
• Exposure: Occupational asbestos exposure in general (insulation work in the main cohort reviewed). The author listed chrysotile and the amphiboles amosite, anthophyllite, crocidolite and tremolite as commercially important forms.
• Main results:
  • In the Selikoff insulation-worker cohort, 2,271 deaths were observed through December 31, 1976, against 1,661 expected according to the text (1,658.9 in Table 2).
  • In that cohort, lung cancer accounted for 486 deaths by best-evidence review, against 106 expected (105.6 in Table 2). Death certificates alone recorded 429.
  • In that cohort, there were 175 deaths from mesothelioma (Table 2: 63 pleural and 112 peritoneal by best evidence) and 166 deaths from asbestosis according to the text (Table 2 gives 168).
  • Death certificates in that cohort recorded 49 pancreatic cancer deaths, which could suggest a marked increase. Further study found only 23, which the author described as not very different from the expected number (17.5 in Table 3; the text says eighteen).
  • Death certificates in that cohort underestimated asbestosis by about one-half (Table 2: 78 by death certificate vs 168 by best evidence).
  • Measured from first exposure, the author stated that lung cancer becomes important after 30 to 35 years, pleural mesothelioma after about 35 years, and peritoneal mesothelioma after about 40 years.
  • The author stated that there is no relationship between cigarette smoking and either pleural or peritoneal mesothelioma. Lung cancer, by contrast, is associated with smoking.
  • The author cited Harries's work at the Devonport Dockyard, where 53 of 55 consecutive mesothelioma cases were in trades other than those directly handling asbestos.
• The authors' conclusion: The authors' view was that individuals who will develop asbestos disease cannot yet be identified, but epidemiologic studies allow assessment of groups. They held that a wide variety of exposures, including bystander and household contact, can lead to disease. They concluded that further investigation is needed to define risks from long-term, low-level exposure in the general population.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Occupational Exposure, Asbestos Bodies, Parenchymal Fibrosis, Fibrosis, Pleural Effusion, Lung Cancer, Insulator.

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