Comparative epidemiology of men exposed to asbestos and man-made mineral fibers

Our plain-English summary of Comparative epidemiology of men exposed to asbestos and man-made mineral fibers, by J.R. Goldsmith (American Journal of Industrial Medicine, 1986).

The study

• Author: J.R. Goldsmith
• Journal: American Journal of Industrial Medicine
• Published: 1986;10(5-6):543-52
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Comparative analyses are presented of selected studies of long-term reactions to occupational exposures to asbestos and man-made mineral fibers (MMMF), with emphasis on studies with dose-response information and long enough period of follow-up to observe lung cancer excess, if it occurred. Uniform dose estimates based on average number of fibers per milliliter were derived and tabulated with the corresponding standard mortality (or morbidity) ratio (SMR), crude probability for each unfavorable outcome, and the likelihood that at least as many deaths would have occurred as a result of the expected numbers under Poisson assumptions. A dose-response relationship was said to have been indicated when the crude probability increased monotonically with dose and/or the Poisson probability decreased and reached a value of less than 0.05. Some arbitrary assumptions had to be made in estimation of the dose, and they may need to be corrected. Gravimetric dose estimates may have given different results. Studies selected for analysis included Quebec asbestos miners and asbestos cement workers exposed to asbestos, and pooled U.S. and European studies of MMMF workers, as well as a sample of cigarette-smoking fiberglass workers whose X-ray films were evaluated for fine nodular or irregular opacities. The lowest dose capable of showing either a statistically significant excess (single point criterion--SP) or the median dose in an apparent dose-response relationship with cause of death or radiological results is tabulated. Radiological changes show a dose-response relationship for all types, with a median dose for asbestos of 2.8 fibers/ml. For fiberglass workers, the median dose of electron-microscopically detected fibers was two orders of magnitude less. For asbestos SP, exposures of 1.4 to 22 fibers/ml were associated with increased lung cancer, while for mineral wool, the minimal level with significant SP increase in lung cancer was an order of magnitude less. Based on fiber or particle counts, man-made mineral fibers appear to be more potent than asbestos with regard to chronic pulmonary disease.

In plain English

This paper did not collect new data. The author took selected published studies of workers exposed to asbestos or to man-made mineral fibers (fiberglass and mineral wool). The author put their exposures on a common scale of average fibers or particles per milliliter and recalculated how likely the observed deaths were by chance. The asbestos studies covered asbestos-cement workers and Quebec asbestos miners followed 20 years or more. The mineral fiber studies covered U.S. and European plant workers and U.S. fiberglass workers who smoked. Among the Quebec miners, lung cancer was above expected in every exposure group but statistically significant only at the two highest levels. In U.S. mineral wool workers, respiratory cancer was significantly raised at two intermediate exposure levels, both well below 1 fiber/ml. The author concluded that, counted by fibers or particles, man-made mineral fibers appear more potent than asbestos for chronic lung disease. The author noted that the dose estimates relied on arbitrary assumptions. The asbestos figures were also for total dust, only part of which was asbestos.

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: Comparative reanalysis of previously published occupational studies. Exposures were converted to a common dose scale and Poisson probabilities were recalculated. No new data were collected.
• Who was studied: Workers from published studies: asbestos-cement workers (Weill et al 1979); Quebec asbestos miners followed 20 years or more (McDonald et al 1980); U.S. fibrous glass and mineral wool workers (Enterline et al 1983); European MMMF workers (Saracci et al 1984); and U.S. fiberglass workers who were current smokers with at least 20 years of exposure, whose X-rays were evaluated (Weill et al 1983).
• Exposure: Asbestos-containing dust in asbestos mining and asbestos-cement manufacture; glass wool (fiberglass) and mineral wool. All doses were expressed as average fibers or particles per milliliter. The article's own text does not name the asbestos fiber types.
• Main results:
  • Quebec asbestos miners followed 20 years or more: lung cancer SMRs were elevated in all exposure categories but significant only at the two highest levels. At 2.8 particles/ml: 24 observed vs 10.9 expected deaths, SMR 2.20. At 6.9 particles/ml: 32 observed vs 12.1 expected, SMR 2.65.
  • Asbestos-cement workers: respiratory cancer appeared increased above an average of 11.0 fibers/ml (over 100 mppcf-years). At the 101-200 mppcf-year level there were 9 observed vs 3.1 expected deaths (SMR 290). Above 200 mppcf-years there were 14 observed vs 6.2 expected (SMR 226). The author's plot did not show a consistent dose-response relationship.
  • U.S. fiberglass workers, nonmalignant respiratory disease: no consistent dose-response, but SMRs were modestly elevated. At the lowest exposure level there were 78 observed vs 57.3 expected deaths (SMR 136.1), which was statistically significant.
  • U.S. mineral wool workers, respiratory cancer: SMRs were 174.3 (13 observed vs 7.46 expected) and 178.2 (17 observed vs 9.54 expected) at the two intermediate exposure levels. Both were significant, with mean exposures well below 1 fiber/ml.
  • Fiberglass workers who smoked, with 20 or more years of exposure: X-ray small opacities were more frequent at higher fiber levels. For all production workers of all ages, the rate was 0.16 (57 examined) at the lowest level and 0.44 (48 examined) at the highest.
  • Median doses in an apparent dose-response for X-ray changes were 2.8 fibers/ml for asbestos and 0.006 for glass or mineral wool, as printed in the summary table.
  • When European data were pooled with U.S. data, the combined set showed significant associations of lung cancer with mineral wool and of other chronic respiratory disease with fiberglass. Pooled p* values were 0.030 and 0.027.
• The authors' conclusion: The author concluded that, based on fiber or particle counts, man-made mineral fibers appear to be more potent than asbestos with regard to chronic pulmonary disease.
• Limitations the authors state:
  • Arbitrary assumptions were made in estimating doses and may need correcting.
  • Dose estimates based on weight of dust (gravimetric) may have given different results.
  • The asbestos exposure figures were total dust, only part of which was asbestos. Asbestos-only exposures would be lower by an unknown amount.
  • Apparent dose-response trends in crude probabilities may reflect age.
  • Some silica exposure was possible in asbestos mining and asbestos-cement work.
  • In the European data, few workers had been followed for 20 years or more. The high exposure category may have come from a different country than the lower ones.

Topics

Medical terms in this study, explained in our Lexicon: Epidemiology, Mineral Fiber, Occupational Exposure, Dose-response relationship, Lung Cancer, Asbestos-Cement.

Related studies

• Historical cohort study of US man-made vitreous fiber production workers: I. 1992 fiberglass cohort follow-up: initial findings — G.M. Marsh, A.O. Youk, et al. (2001)
• Mortality among a cohort of US man-made mineral fiber workers: 1985 follow-up — G.M. Marsh, P.E. Enterline, et al. (1990)
• Man-made mineral fiber hazardous properties assessment using transgenic rodents: example of glass fiber testing — M.C. Bottin, J.C. Vigneron, et al. (2003)
• Silica, asbestos, man-made mineral fibers, and cancer — K. Steenland, L. Stayner (1997)
• Comparative pulmonary responses to inhaled inorganic fibers with asbestos and fiberglass — K.P. Lee, C.E. Barras, et al. (1981)
• Man-made mineral fibers and interstitial lung diseases — E. Fireman (2014)

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