Relationship of mortality to measures of environmental asbestos pollution in an asbestos textile factory

Our plain-English summary of Relationship of mortality to measures of environmental asbestos pollution in an asbestos textile factory, by J. Peto, R. Doll, C. Hermon, et al (The Annals of Occupational Hygiene, 1985).

The study

• Authors: J. Peto, R. Doll, C. Hermon, W. Binns, R. Clayton, T. Goffe
• Journal: The Annals of Occupational Hygiene
• Published: 1985;29(3):305-55
• Cited by: 162 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. 000504).

In plain English

This mortality study followed workers at an asbestos textile factory in Rochdale, England, to 30 June 1983. The factory used mainly chrysotile, with small amounts of crocidolite. The main group was 3211 men first employed between 1933 and 1974. Two smaller groups, 145 men employed before 1933 and 283 women, were also updated. Exposure of men in the main group was estimated from dust measurements made since 1951, with earlier exposure assigned from 1951-55 levels. In the main group, lung cancer deaths were 1.31 times those expected from national rates. The excess was concentrated in men with ten or more years in scheduled (dusty) areas, observed 20 or more years after first employment (ratio 2.09). Men with under ten years in scheduled areas had one mesothelioma death, against 25 expected at the rates of longer-serving men. Lung cancer risk rose with estimated cumulative dose. Combining their results with a South Carolina textile study, the authors suggested a rounded estimate for prediction. They warned their risk estimates were of doubtful accuracy because exposure data came largely from static particle counts.

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: Retrospective cohort mortality study of factory employees, comparing observed deaths with those expected at national (and Rochdale) rates, with matched case-control analyses of lung cancer and mesothelioma within the cohort
• Who was studied: Employees of an asbestos textile factory in Rochdale, U.K., followed to 30 June 1983: (i) 145 men with at least 20 yr in scheduled areas including some time before 1933; (ii) 283 women first employed in 1933 or later with 10 or more yr in scheduled areas; (iii) a principal cohort of men first employed 1933 to 1974, totalling 3650 men and reduced to 3211 after exclusions
• Exposure: Asbestos textile manufacture using chrysotile as the principal fibre, plus small amounts of crocidolite (about 5% of the amount used for textile manufacture, 1932 to 1968); no amosite in production. Individual exposure for the principal cohort was estimated from static particle counts (particles per ml, 1951 to 1960) and fibre counts (fibres per ml, from 1961), with 1 fibre per ml taken as 35 particles per ml. Exposure from 1933 to 1950 was assigned mostly from 1951-55 levels.
• Main results:
  • Principal cohort (3211 men): lung cancer mortality was significantly raised compared with both national and Rochdale rates, SMR 1.31, P less than 0.01
  • Principal cohort: in men employed in scheduled areas for ten or more years and observed 20 or more years after first employment, the lung cancer SMR was 2.09, against 1.13 for all other men and at all other times
  • Principal cohort: at the rates seen in men with ten or more years' exposure, men with less than 10 yr exposure in scheduled areas would have been expected to have 25 mesothelioma deaths; only one was observed
  • Dose-response for lung cancer, converted at 35.3 particles per fibre: the SMR increased by 0.0054 per fibre per ml-year for the entire principal cohort and by 0.0150 per fibre per ml-year for men first employed in 1951 or later. The difference between the two estimates was statistically significant (P less than 0.05)
  • In each group of men employed 20 or more years in scheduled areas, the relative risk of lung cancer more than 35 yr after first exposure was lower than between 20 and 35 yr after first exposure
  • Pre-1933 group: among the 69 men who worked ten or more years before 1933, there were 13 lung cancer deaths against 1.58 expected
  • Women's group: in women first employed before 1950 there were 4 lung cancer deaths against 1.44 expected. The authors said the numbers of deaths were too few for material conclusions
  • Principal cohort: lung cancer was elevated in men first exposed before 1951 with less than a year's exposure (44 observed, 30.51 expected; P less than 0.05). The authors thought this was likely due largely to chance or selection bias
  • Long-term employees observed 20 or more years after first employment had an increase in gastro-intestinal cancer that was not quite statistically significant (SMR 1.53, P=0.1)
• The authors' conclusion: The authors concluded that their lung cancer estimates were consistent with those from a South Carolina chrysotile textile study (McDonald et al., 1983). For prediction, they suggested a rounded intermediate estimate: SMR = 1 + 0.01 x cumulative exposure in fibres per ml-years. They also suggested that their mesothelioma estimate may be too high for pure chrysotile, because crocidolite was also used in the factory
• Limitations the authors state:
  • No routine dust measurements were taken before 1951, so the exposure categories for men employed 1933 to 1950 were less firmly based
  • For the men employed before 1933, no early dust levels were measured, so their results are of little value for estimating the dose-risk relationship
  • The heaviest exposures were rarely measured, and particle and fibre counts correlate poorly
  • Information on the employees' smoking habits was too incomplete to use
  • Because some crocidolite was used, the mesothelioma risk estimate may be too high for pure chrysotile
  • There were too few mesothelioma cases to test the mesothelioma model stringently
  • The employee register appeared to be seriously incomplete for Asian workers (who were excluded) and about 95% complete for other workers
  • The exposure estimates rest largely on static particle counts converted to fibre counts, so the resulting risk estimates are of doubtful accuracy

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestos textiles, Asbestosis.

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