Mesothelioma in Relation to Asbestos in the United States

Our plain-English summary of Mesothelioma in Relation to Asbestos in the United States, by I.J. Selikoff, J. Churg, E.C. Hammond (1964).

The study

• Authors: I.J. Selikoff, J. Churg, E.C. Hammond
• Published: 92nd Annual Meeting of the American Public Health Association, October 6th 1964
• Type of article: Conference paper
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This 1964 conference paper reported three investigations into whether mesothelioma of the pleura (the chest lining) and of the peritoneum (the abdominal lining) was related to asbestos exposure in the United States. First, in 2,500 consecutive autopsies performed by two pathologists from 1953 to 1964, asbestosis was found in 26 cases. Of these, 4 had pleural mesothelioma and 3 had peritoneal mesothelioma, and no mesothelioma was found in the absence of asbestosis. Second, a review of 45 mesothelioma cases from the Armed Forces Institute of Pathology found asbestos bodies in the lung tissue of 12. Third, among 307 deaths from 1943 to August 1964 among members of New York Local 12 and Newark, New Jersey Local 32 of the insulation workers' union, 10 deaths were from mesothelioma (4 pleural, 6 peritoneal). None of these ten men developed the tumor less than 32 years after his first exposure. The authors concluded that mesothelioma is an important complication of asbestos exposure under relatively light, intermittent working exposure, and may not be a problem of crocidolite alone. They noted small numbers, selected autopsy cases and likely undercounting.

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: Three-part investigation: review of a pathologists' autopsy series, re-examination of mesothelioma cases held by the Armed Forces Institute of Pathology, and a mortality survey of asbestos insulation union members (conference presentation)
• Who was studied: (1) 2,500 consecutive autopsies, 1953 to 1964, from the personal series of two pathologists, including 1,020 adult males; (2) 45 cases (20 pleural, 25 peritoneal) of diffuse pleural or peritoneal malignancy in the Armed Forces Institute of Pathology files in which mesothelioma was strongly considered and some lung tissue was available; (3) 1,522 men who were members at any time from December 31, 1942 to December 31, 1962 of New York Local 12 and Newark, New Jersey Local 32 of the International Association of Heat and Frost Insulators and Asbestos Workers, with 307 deaths from January 1, 1943 to August 31, 1964
• Exposure: Asbestos exposure, shown in the autopsy series by asbestosis and in the pathology series by asbestos bodies in lung tissue. The union members were insulation workers, mainly in construction, described as having relatively light, intermittent exposure to asbestos-containing insulation materials. The paper discusses crocidolite and chrysotile import figures but does not state which fiber types the insulation workers handled.
• Main results:
  • Autopsy series: asbestosis was recorded in 26 cases. Among these 26, pleural mesothelioma was present in 4 (15%), peritoneal mesothelioma in 3 and bronchogenic carcinoma in 7.
  • Autopsy series: no case of mesothelioma was found in the absence of asbestosis.
  • Armed Forces Institute of Pathology cases: asbestos bodies were found in 12 of 45 mesothelioma cases with lung tissue available, in 6 of 20 pleural cases and in 6 of 25 peritoneal cases (according to the text).
  • Armed Forces Institute of Pathology cases: in 2 of the 12 cases asbestos bodies were already known to be present; in the other 10, this review first brought them to notice.
  • Insulation workers: among 307 consecutive deaths, ten were from mesothelioma, four of the pleura (1.3%) and six of the peritoneum (1.9%). The authors described this as almost 3 percent of deaths.
  • Insulation workers: among the 307 deaths, 53 (17.3%) were from bronchogenic carcinoma and 17 (5.5%) from asbestosis.
  • Insulation workers who died of mesothelioma (10 men): age at death ranged from 50 to 75 (average 59). Exposure lasted 15 to 43 years (average 31.4). No man developed the tumor less than 32 years after onset of exposure (average 38.5).
  • For comparison, the authors cited an American Cancer Society prospective study of 1,048,183 men and women aged 30 to 89, traced through September 30, 1962. Of 31,652 who had died, three had died of pleural mesothelioma and none of peritoneal mesothelioma.
  • One man in the autopsy series, a carpenter with pleural mesothelioma, denied ever having seen, used or handled any asbestos product, yet asbestos bodies and fibers were found in his lung after death.
• The authors' conclusion: The authors concluded that ten mesothelioma deaths among 307 consecutive deaths was extraordinarily high and showed that mesothelioma is an important complication of asbestos exposure. They said this applied to U.S. working conditions of the recent past with relatively light and intermittent exposure, that mesothelioma may not be a problem of only one kind of asbestos (crocidolite), and that it is not limited to South Africa.
• Limitations the authors state:
  • Relying only on finding asbestos bodies may grossly underestimate how often asbestos is present in tissue.
  • In many of the pathology cases very little lung tissue was available, and it was not known which part of the lung it came from.
  • The numbers of mesothelioma cases were small, so findings may be due to chance.
  • Autopsy series are selected cases, so the 7 mesotheliomas among 26 asbestosis autopsies cannot be taken as the true incidence.
  • Asbestos bodies may occasionally be found in normal lungs without asbestosis, because of chance environmental contact.
  • The insulation worker estimate may undercount mesothelioma, because only 110 of the 297 non-mesothelioma deaths had histological confirmation.

Topics

Medical terms in this study, explained in our Lexicon: Mesothelioma, Pleura, Peritoneum, Asbestos Exposure, Pleural Mesothelioma, Peritoneal Mesothelioma, Pathology, Asbestos Bodies.

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