Predictions of Mortality from Mesothelial Tumours in Asbestos Factory Workers

Our plain-English summary of Predictions of Mortality from Mesothelial Tumours in Asbestos Factory Workers, by Muriel L. Newhouse, G. Berry.

The study

• Authors: Muriel L. Newhouse, G. Berry
• Published: n.d.
• Type of article: Journal article
• 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

The authors used death records from a London asbestos textile and insulation factory, where chrysotile, amosite and crocidolite were all used and mixed exposures were the rule, to predict deaths from mesothelial tumours up to the year 2000. About 3,000 men and 700 women were included. Up to 30 September 1972, among men who survived at least 10 years after first employment, 31 of 426 deaths (7.3%) were from a mesothelial tumour. For women it was 14 of 158 (8.9%). Of the 45 tumours, 23 were pleural and 22 peritoneal. The rate rose from 6 per 100,000 subject years at 10 to 15 years after first exposure to 318 at 30 or more years. It was higher with longer and more severe exposure. Using a mathematical model, the authors projected 121 to 194 tumours in men and 42 to 59 in women for 1971 to 2000, peaking in the 1980s. The authors concluded these tumours would cause 7 to 11% of male deaths and somewhat more among women. They described the projections as uncertain because data were limited.

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 of factory worker cohorts, used with a mathematical model to project future deaths from mesothelial tumours
• Who was studied: About 3,000 men (first employed from 1933 up to 1964, excluding laggers) and 700 women (first employed 1936 to 1942) at an asbestos factory in the East End of London that operated from 1913 to 1968
• Exposure: Chrysotile, amosite and crocidolite asbestos in the manufacture of asbestos textiles and heat insulating materials, with mixed exposures the rule. Workers were grouped as 'severe' or 'low-moderate' exposure and as less than 2 years or 2 years or more of exposure.
• Main results:
  • Men who survived at least 10 years after first employment: up to 30 September 1972, 31 of 426 deaths were from a mesothelial tumour (7.3% of all deaths)
  • Women: 14 of 158 deaths were from a mesothelial tumour (8.9%)
  • Of the 45 mesotheliomas in the two groups, 23 were pleural and 22 peritoneal
  • The mesothelioma rate per 100,000 subject years rose from 6 at 10 to 15 years after first exposure to 318 at 30 or more years
  • In workers with low-moderate exposure and short employment, the mesothelioma rate was about one sixth of the rate in those with severe and long exposure (these rates were not adjusted for differences in follow-up)
  • Men: projections gave 121 to 194 mesothelial tumours for 1971 to 2000, and 7.3% to 10.8% of deaths due to mesotheliomas by 2000
  • Women: projections gave 9.1% to 12.0% of deaths due to mesotheliomas by 2000, with 42 to 59 tumours predicted for 1971 to 2000
  • Even under the lowest estimates, the peak was predicted for the 1980s, with incidence at the turn of the century similar to the level at the time of writing
  • From incomplete data for 1971 up to mid-1973, 13 deaths from mesotheliomas had been confirmed
• The authors' conclusion: The authors estimated that mesothelial tumours would account for between 7% and 11% of total mortality in men and somewhat more in women. They expected the highest numbers in the 1980s, followed by a decline as the cohort shrank through deaths from all causes.
• Limitations the authors state:
  • The authors called the projection hazardous because it was based on only 45 mesotheliomas observed over 20 years
  • The model's parameter estimates were imprecise because of the limited data
  • All-cause mortality in the cohorts, and national death rates themselves, may change over the next 30 years
  • The dust hazard in the factory may have changed during the period of exposure
  • The rates by exposure group were not adjusted for differences in length of follow-up between groups

Topics

Medical terms in this study, explained in our Lexicon: Chrysotile, Amosite, Crocidolite.

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