Industrial Toxicology, Third Edition

Our plain-English summary of Industrial Toxicology, Third Edition (1975).

The study

• Published: 1975
• Type of article: Book excerpt
• Our copy: from Johns-Manville's own medical library.

In plain English

This textbook section on asbestos, from Industrial Toxicology, Third Edition, is not an original study. It drew on published reports and the authors' clinical experience. It described asbestosis, pleural plaques, lung cancer, and pleural and peritoneal mesothelioma. Noting that published reports disagreed on whether asbestosis progresses after exposure stops, the authors judged, on balance and from HLH's experience, that it becomes progressive once the dose causes measurable lung function abnormality. They called pleural effusion with a history of asbestos exposure practically pathognomonic of (almost always pointing to) malignant mesothelioma, while also citing reports of effusion without malignancy. Asbestos bodies in sputum or lung biopsy, they wrote, prove exposure only. They stated that chrysotile can be mined and used safely with engineering control and that crocidolite is a serious hazard even in small doses. They stated that the mesothelioma risk from amosite alone was unknown as of January 1974. The authors concluded that engineering control must be strictly applied to workroom fiber and dust levels. They noted that past exposures may be impossible to assess accurately.

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: Textbook chapter section (narrative review of published literature plus the authors' clinical experience)
• Who was studied: No defined study population. The section draws on published reports and on clinical experience, including New England shipyard workers studied by HLH in the 1960s. These workers had used three forms of commercially used asbestos while removing old insulation from ships' boilers and pipes.
• Exposure: Industrially used forms of asbestos (chrysotile, anthophyllite, amosite, crocidolite) in uses such as heat insulation, brake linings, pipe and furnace fittings, asbestos textiles, vinyl asbestos tile, fireproofing and asbestos cement pipe
• Main results:
  • The authors noted that reports in the literature do not agree on whether the pulmonary fibrosis of asbestosis progresses once exposure has stopped
  • On balance and judging from HLH's experience, the authors stated that asbestosis becomes progressive if the dose reaching the lower respiratory tract is large enough to cause measurable lung function abnormality
  • The authors stated that pleural effusion, with or without pulmonary infiltrates, together with a history of asbestos exposure is practically pathognomonic of malignant mesothelioma
  • The authors also cited reports of pleural effusion without malignancy and stated that such pleural reactions may occur without asbestosis or malignancy
  • The authors stated that finding asbestos bodies in sputum or lung biopsy proves exposure only
  • In their summary of fiber types, the authors stated that chrysotile can be mined and used safely with engineering control
  • The authors stated that crocidolite is a serious hazard even in small doses, especially in combination with chrysotile and/or amosite
  • The authors stated that the threat of malignant mesothelioma from amosite exposure alone was unknown as of January 1974, while the risk from crocidolite was definitely established
  • The authors stated there is no specific therapy for asbestosis. Steroids had been tried without success, and oxygen had helped control symptoms.
  • The authors wrote that there were to date no reports of asbestos-related malignancy in nonsmokers
  • The authors reported that the most recent (1973) printed limit for all types of asbestos fibers was 5 fibers per ml greater than 5 microns in length of respirable size. It was suggested by the British Hygiene Society in 1968 and adopted by the United States, with agitation to reduce it to 2 fibers.
• The authors' conclusion: The authors concluded that study of old and new reports of asbestosis makes clear that engineering control must be strictly applied to workroom levels of both fiber and dust, and that safe levels are constantly changing
• Limitations the authors state:
  • The precise character of total asbestos dust exposure in an individual worker or group may be impossible to assess accurately in retrospect, and recorded disease may be due to a mixture of inhaled material
  • The authors acknowledged there are no entirely convincing studies to prove that a worker with asbestosis should leave exposure. The recommendation rests on clinical experience that the fibrosis is progressive.
  • Sampling methods and fiber counting were complex and not yet standardized

Topics

Medical terms in this study, explained in our Lexicon: Pleural Plaques, Lung Cancer, Peritoneal Mesothelioma, Pleural Effusion, Asbestos Exposure, Mesothelioma, Asbestos Bodies, Sputum.

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