Cancer Risk Of Insulation Workers In The United States

Our plain-English summary of Cancer Risk Of Insulation Workers In The United States, by I.J. Selikoff, E.C. Hammond, H. Seidman (1973).

The study

• Authors: I.J. Selikoff, E.C. Hammond, H. Seidman
• Published: Biological Effects Of Asbestos (J.C. Wagner, Editor), Lyon: Iarc Scientific Publications, Volume 8, Pp. 209-216 (1973)
• Type of article: Conference paper
• Our copy: from Johns-Manville's own medical library, J-M no. 001319. The article is still under copyright, so we describe it here rather than post it.

In plain English

This report followed deaths to 31 December 1971 in three groups of men exposed to asbestos insulation materials. The groups were 370 surviving members of New York-New Jersey insulation workers' union locals, 17,800 members of the insulation workers' union in the United States and Canada on 1 January 1967, and 933 men hired in 1941-45 at an eastern US factory making amosite asbestos insulation materials. Among 877 fully traced factory workers, four hundred and eighty-four died. These deaths included 73 from lung cancer where 11.41 were expected, 26 from gastro-intestinal cancer where 12.86 were expected, seven from mesothelioma and 27 from asbestosis. Factory workers employed under three months had 13 lung cancer deaths against 3.55 expected, and those employed a year or more had 45 against 4.09. In the US-Canada group, lung cancer was raised 15-19 years after work began (18 deaths against 4.86 expected), but most such deaths came 30-39 years or later. The authors found no evidence that chrysotile in insulation work carried more risk than amosite, or the reverse. They concluded the risks were associated with the asbestos insulation materials themselves. Some article text is missing.

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: Mortality follow-up (cohort) studies of three groups of workers, comparing observed deaths with deaths expected from US national death rates
• Who was studied: Three groups. (1) The 632 members of the New York-New Jersey insulation workers' union locals on 1 January 1943, of whom 370 were alive on 1 January 1963 and were followed to 31 December 1971. (2) 17,800 members of the insulation workers' union in the United States and Canada on 1 January 1967, followed to 31 December 1971. (3) 933 men hired in 1941-45 at an amosite insulation materials factory in an eastern US city, traced to 31 December 1971.
• Exposure: Asbestos insulation materials. Insulation workers were exposed to chrysotile (mainly in general construction and industrial work) and amosite (mainly in ship insulation). Factory workers made amosite insulating block, pipe covering and mattresses. Crocidolite was not used for US insulation work in the study period.
• Main results:
  • Amosite factory: four hundred and eighty-four deaths among the 877 men fully traced to 31 December 1971
  • Amosite factory: 73 lung cancer deaths where 11.41 were expected, and 26 gastro-intestinal cancer deaths (including oesophagus) where 12.86 were expected
  • Amosite factory: mesothelioma caused seven deaths and asbestosis 27
  • Gastro-intestinal cancer: 41 deaths where 13.0 were expected in the New York-New Jersey group, and 55 where 27.3 were expected in the US-Canada group (printed as 'S5'; Table 2 confirms 16 stomach + 26 colon/rectum + 13 oesophagus = 55)
  • Amosite factory, men employed more than one year: 10 lung cancer deaths where 0.65 were expected, 10-14 years from onset of work
  • US-Canada group: lung cancer death rates were significantly increased 15-19 years from onset, with 18 deaths where 4.86 were expected
  • Insulation workers: in terms of numbers, most lung cancer deaths occurred 30 to 39 years from onset of exposure, or later
  • US-Canada group: the authors saw no striking variations in lung cancer by age at which asbestos work began
  • Amosite factory, men employed less than three months: 13 lung cancer deaths where 3.55 were expected; men employed three to eleven months showed much the same increase
  • Amosite factory, men employed one year or more: 45 lung cancer deaths where 4.09 were expected
  • New York-New Jersey group, 337 men with shipyard histories obtained by interview: mortality in men with shipyard employment (greater potential for amosite exposure) did not differ substantially from that of men without it
  • US-Canada group, 1967-1971: no apparent significant difference in mortality between union locals engaged entirely in shipyard work and locals in the south-west, mid-west and central states
  • The authors found no evidence that chrysotile in insulation work was associated with greater risk than amosite, or the reverse
  • In their summary, the authors stated that among US asbestos insulation workers approximately one death in five was the result of lung cancer
• The authors' conclusion: The authors concluded that the cancer risks they described were associated with the asbestos insulation materials themselves, without any need to invoke other insulation materials.
• Limitations the authors state:
  • Comparing chrysotile and amosite is difficult because groups differing in fiber type may also differ in type and intensity of exposure, duration of exposure and time since onset
  • Studying age at onset is complicated by changes in cigarette smoking habits over the past 50 years
  • Cancers at other sites could not be evaluated because such tumours are infrequent and there were too few observations
  • Members of the non-shipyard locals may still have done some shipyard work in the past
  • Follow-up of the factory cohort had reached only 25-30 years from onset of exposure

Topics

Medical terms in this study, explained in our Lexicon: Insulator, Amosite, Lung Cancer, Mesothelioma, Chrysotile.

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