Decline in death rates among asbestos insulation workers 1967-1986 associated with diminution of work exposure to asbestos

Our plain-English summary of Decline in death rates among asbestos insulation workers 1967-1986 associated with diminution of work exposure to asbestos, by H. Seidman, I.J. Selikoff (Annals of the New York Academy of Sciences, 1990).

The study

• Authors: H. Seidman, I.J. Selikoff
• Journal: Annals of the New York Academy of Sciences
• Published: 1990;609:300-17; discussion 317-8
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 004083).

Abstract

We investigated the consequences of a reduction of asbestos exposure among a cohort of asbestos insulation workers in the United States and Canada. By examining data over three time periods during which asbestos exposure declined, we obtained data indicating that reduction in exposure was associated with an observable decrease in mortality, with little time lag, from some asbestos-associated diseases, even among workers previously exposed for 20 or more years.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

This prospective study followed the mortality of 17,800 men who belonged to the asbestos insulation workers' union in the United States and Canada on January 1, 1967, through December 31, 1986. They had used insulation containing chrysotile in early years and chrysotile plus amosite later. Exposure fell after an OSHA standard in 1972 and the removal of asbestos from new insulation in 1972-1973, though the reduction was not measured and exposure did not stop entirely. The authors compared death rates in 1967-1972, 1973-1979 and 1980-1986 among men with similar time since first exposure. Death rates from lung cancer, peritoneal mesothelioma and asbestosis generally fell significantly among men less than 40 years from first exposure. No decline was seen for pleural mesothelioma. The text reported no decline among men 40 or more years from first exposure, though figure captions put this cutoff at 45 years for peritoneal mesothelioma and 50 for asbestosis. The authors concluded that controlling asbestos exposure can lower the risk of death from some asbestos-associated diseases. They noted that reduced smoking may have contributed to the lung cancer decline, and that the effect of replacement man-made mineral fibers is unknown.

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: Prospective cohort mortality study comparing observed and expected deaths (and death rates per 100,000 person-years) in three time periods, 1967-1972, 1973-1979 and 1980-1986, within groups with similar years since first exposure
• Who was studied: 17,800 men who were members of the International Association of Heat and Frost Insulators and Asbestos Workers in the United States and Canada on January 1, 1967, followed to December 31, 1986 (301,592.6 person-years at risk)
• Exposure: Asbestos insulation work. Materials contained chrysotile in early years and chrysotile plus amosite later. The Canadian chrysotile is believed to have contained small proportions of tremolite, generally less than 1%. Crocidolite was not used by these workers. Exposure was reduced after an OSHA standard in 1972 and the removal of asbestos from new insulation materials in 1972-1973.
• Main results:
  • Among groups with less than 40 years since onset of exposure, death rates from lung cancer, peritoneal mesothelioma and asbestosis generally showed a significant decrease across the three periods
  • The text reported no decline for pleural mesothelioma, and no decline in groups 40 or more years from onset
  • Figure caption: pleural mesothelioma death rates showed no decline in 1967-1986
  • Figure caption: peritoneal mesothelioma death rates declined among men 15-44 years from onset of employment, but not among those 45 or more years from onset
  • Figure caption: asbestosis death rates declined except among workers with 50 or more years from onset of exposure
  • Example from the lung cancer table (best evidence) for men 30-34 years from onset: the death rate per 100,000 person-years was 1066.8 in 1967-1972, 955.5 in 1973-1979 and 554.5 in 1980-1986
  • In the second ten years of follow-up (1977-1986), 2,680 deaths occurred among the 15,529 men who survived the first 10 years
• The authors' conclusion: The authors concluded that control of asbestos exposure can lead to a decrease in risk of death from some asbestos-associated diseases. They described the risk as at least partly, but not entirely, reversible by control of further exposure, and said no benefit was seen among workers with 40 or more years of exposure.
• Limitations the authors state:
  • Studying changes over time is difficult even in the same cohort, because later survivors differ from the earlier population at risk
  • Smoking-specific comparisons were difficult to make
  • Reduced cigarette smoking or lower tar and nicotine content may have contributed to the decline in lung cancer and perhaps asbestosis death rates. The authors considered it unlikely to have influenced peritoneal mesothelioma.
  • The reduction in exposure was not measured
  • Exposure did not stop altogether. Older stock, maintenance and repair, and abatement work continued to involve asbestos.
  • The effect of the man-made mineral fibers that replaced asbestos is unknown
  • The study gives no information on crocidolite
  • SMRs based on best-evidence diagnoses are given for information only, because they are not strictly comparable with expected deaths based on death certificates

Topics

Medical terms in this study, explained in our Lexicon: Insulator, Asbestos Exposure.

Related studies

• Influence of age at death on accuracy of death certificate disease diagnosis: findings in 475 consecutive deaths of mesothelioma among asbestos insulation workers and asbestos factory workers — I.J. Selikoff (1992)
• Asbestos-associated deaths among insulation workers in the United States and Canada, 1967-1987 — I.J. Selikoff, H. Seidman (1991)
• Use of death certificates in epidemiological studies, including occupational hazards: variations in discordance of different asbestos-associated diseases on best evidence ascertainment — I.J. Selikoff, H. Seidman (1992)
• Asbestos exposure, cigarette smoking and death rates — E.C. Hammond, I.J. Selikoff, et al. (1979)
• Death certificates in epidemiological studies, including occupational hazards: inaccuracies in occupational categories — I.J. Selikoff (1992)
• Mortality experience of insulation workers in the United States and Canada, 1943--1976 — I.J. Selikoff, E.C. Hammond, et al. (1979)

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