An Evaluation Of Claims For Occupational Factors In Cancer Of The Lungs

Our plain-English summary of An Evaluation Of Claims For Occupational Factors In Cancer Of The Lungs, by W.E. Smith (1953).

The study

• Author: W.E. Smith
• Published: Acta Unio Internationales Contra Cancrum 9:50-58 (1953)
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library, J-M no. 001899. The article is still under copyright, so we describe it here rather than post it.

In plain English

This paper was a review. The author weighed claims linking lung cancer to radioactive ores, nickel, arsenic, chromates, asbestos, coal tar and isopropyl alcohol production. On asbestos, the author cited a 1947 British factory inspectors' report that recorded primary lung cancer in 31 of 235 cases of asbestosis, which is 13.2 in every 100. The report set this against 1.32 for a large group of silicotic lungs; the unit is missing from the scanned text. Both figures counted cancers among reported cases, not all workers. From Registrar General death statistics, the author calculated a general-population lung cancer death rate for England and Wales of 1.36, unit likewise lost. A Finnish series of 126 asbestosis cases had no cancer. The author noted that Finnish asbestos work went back only 20 years and that the Finnish series used X-rays of living workers, not autopsies. The author judged cases from Germany, the United States and Canada too few to be convincing. The author concluded that reports of occasional cases must be replaced by sound statistical study of groups of workers.

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 published reports, official statistics and personal communications on claimed occupational causes of lung cancer, followed by a transcript of the conference discussion
• Who was studied: Workers in several industries and countries, as described in other reports: Schneeberg and Joachimsthal miners, a British nickel refinery, arsenic-handling plants, chromate plants, asbestos workers with asbestosis in Great Britain and Finland, gas-works and coal tar workers, and isopropyl alcohol production workers in the United States
• Exposure: For asbestos: work in the asbestos industry leading to asbestosis. The question was whether asbestosis predisposes to lung cancer. No fiber type is named. Other exposures reviewed were radioactive ores and radon, arsenic, nickel, chromates, coal tar products, cutting oils and 'isopropyl oil'.
• Main results:
  • The 1947 report of Britain's Chief Inspector of Factories, as cited by the author, recorded primary lung cancer in 31 of 235 cases of asbestosis. The report gives a lung cancer rate of 13.2 for these asbestotic lungs, which equals 31 of 235 expressed per 100. It compares this with 1.32 for a large group of silicotic lungs reported to the same office. The unit for 1.32 did not survive scanning, and no denominator is given for the silicotic group. Both figures concern reported case series, not all asbestos or silica workers.
  • The author calculated a lung cancer mortality rate of 1.36 for the general population of England and Wales from Registrar General death statistics. This figure rests on a different basis (death statistics) from the asbestotic and silicotic lung figures. Its unit did not survive scanning.
  • According to the 1947 report, British asbestosis cases who died with lung cancer had a mean exposure of 16.5 years. Asbestosis cases who died without evidence of lung cancer had a mean exposure of 13.4 years.
  • In a Finnish series of 126 asbestosis cases reported by Wegelius, there were no cases of carcinoma. The most advanced Finnish cases, only 9 people, had an average exposure of 11.5 years.
  • In 1950, the British Factory Inspector's Office recorded only one lung cancer case among people whose asbestos employment fell wholly after the 1931 ventilation regulations. The author later learned that additional cases had occurred.
  • Lung cancer had occasionally been described at autopsy in people with asbestosis in Germany, the United States and Canada. The author judged these cases too few to provide convincing evidence of an occupational tumor hazard in those countries.
  • Among 71 men employed 5 or more years in an isopropyl alcohol production unit (unpublished data from other authors), there were 4 nasal sinus cancers, one lung cancer, one laryngeal cancer and one vocal cord papilloma.
• The authors' conclusion: The author concluded that occasional case reports suggesting an occupational cause must be replaced by sound statistical study of occupational groups. Claims of new occupational causes need evidence of more tumors than in properly selected control populations.
• Limitations the authors state:
  • The British asbestos cases had not yet been analysed against the population at risk.
  • Asbestos work in Finland had gone on for only 20 years, which limits the Finnish comparison.
  • The British and Finnish figures came from different sources: autopsies versus X-rays of living, working people.
  • Working conditions differ between countries and over time.
  • The author knew of no observations of lung cancer in asbestos workers from other countries.

Topics

Medical terms in this study, explained in our Lexicon: Lung Cancer.

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