Respiratory cancer and exposure to man-made vitreous fibers: a systematic review

Our plain-English summary of Respiratory cancer and exposure to man-made vitreous fibers: a systematic review, by D. Berrigan (American Journal of Industrial Medicine, 2002).

The study

• Author: D. Berrigan
• Journal: American Journal of Industrial Medicine
• Published: 2002;42(4):354-62
• Type of article: Meta-analysis, Systematic review
• Cited by: 18 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Man-made vitreous fibers (MMVF's) have some structural features similar to those found in asbestos. This has lead to concern that exposure to MMVF's could increase the risk of respiratory cancer.

Methods: Bibliographic resources were used to identify 10 case-control and 10 cohort studies, which analyzed the relationship between exposure to MMVF's and cancer of the respiratory system. Standardized mortality ratio's (SMR's) were extracted from the cohort studies for a meta-analysis.

Results: A significant increase in SMR was observed for workers exposed to rock and glass wool, but not in workers exposed to glass filament. Meta-analysis of SMR's after stratification by fiber type resulted in aggregate estimates of risk of 1.23 (95% CI = 1.10-1.38), 1.08 (95% CI = 0.93-1.26), and 1.32 (95% CI = 1.15-1.52) for exposure to glass wool, glass filament, and rock wool, respectively. Some or all of the increased mortality could be attributed to tobacco use.

Conclusions: The results highlight the difficulty of assessing small increases in risk of respiratory cancer potentially caused by occupational exposure in populations with high prevalence of tobacco use.

Published 2002 Wiley-Liss, Inc.

In plain English

This single-author article was a systematic review and meta-analysis of studies on man-made vitreous fibers (glass wool, glass filament, and rock/slag wool) and cancer of the respiratory system. The author identified 10 cohort studies and 10 case-control studies, all from North America or Europe. Pooling the cohort studies, the combined standardized mortality ratio (observed deaths compared with expected deaths) was 1.23 (95% confidence interval 1.13 to 1.33) for all exposures, 1.23 (1.10 to 1.38) for glass wool, 1.08 (0.93 to 1.26) for glass filament, and 1.32 (1.15 to 1.52) for rock wool. Among the case-control studies, only one reported an increase whose confidence interval excluded 1.0. None of the studies that examined exposure levels found a statistically significant trend between exposure and risk. Using local rather than national death rates lowered the estimates in most comparisons, and only one cohort study controlled for smoking. The author stated that some or all of the increased mortality could be attributed to tobacco use and judged the case for or against a causal relationship incomplete. The author also concluded that precautions to control exposure continued to seem worthwhile.

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: Systematic review with meta-analysis of cohort studies (fixed-effects pooling of standardized mortality ratios); case-control studies were reviewed but not pooled
• Who was studied: 10 cohort and 10 case-control studies of workers, identified through Medline, the Index of Dissertation Abstracts, ToxLine and bibliographies. All were from North America or Europe. Most covered production workers, and most subjects were white men. Cohort sizes ranged from 416 to over 32,000 people.
• Exposure: Occupational exposure to man-made vitreous fibers: glass wool, glass filament, and rock/slag wool. In all but one cohort the workers were in production; the exception was the prefabricated housing industry.
• Main results:
  • Pooled SMR for respiratory cancer mortality across all cohort studies: 1.23 (95% CI 1.13–1.33)
  • Pooled SMR by fiber type: glass wool 1.23 (95% CI 1.10–1.38), glass filament 1.08 (95% CI 0.93–1.26), rock wool 1.32 (95% CI 1.15–1.52)
  • In the case-control studies, odds ratios adjusted for smoking ranged from 0.55 to 2.03. Only the Bruske-Hohlfeld et al. [2000] estimates had confidence intervals excluding 1.0.
  • Standardizing with local instead of national mortality rates lowered the estimated risk in all but one very small study
  • Of four studies with significantly elevated SMRs based on national rates, two were no longer significantly elevated when local rates were used
  • None of the studies relating quantitative exposure estimates to risk found a statistically significant trend
• The authors' conclusion: The author concluded that there were elevated mortality rates in some cohorts exposed to rock and glass wool but not glass filament, with no evidence of a dose–response relationship. Some or all of the increased mortality could be attributed to tobacco use. The case for or against a causal relationship was described as incomplete. The author stated that precautions to control exposure, particularly to glass, rock and slag wool, continued to seem worthwhile.
• Limitations the authors state:
  • Only one cohort study controlled for smoking. It is not known whether smoking adjustment would remove the excess risk in the other cohorts.
  • Mixing local-rate and national-rate SMRs likely slightly lowered the pooled fiber-type estimates
  • There were too few studies per fiber type to test for publication bias within types
  • Case-control results were not pooled because they were heterogeneous
  • Exposure data in the underlying studies could be inadequate
  • A full assessment of causation was beyond the scope of the article

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer.

Medical terms in this study, explained in our Lexicon: Vitreous, Systematic Review, standardized mortality ratio (SMR), Meta-Analysis, Occupational Exposure.

Related studies

• Man-made vitreous fibers and risk of respiratory system cancer: a review of the epidemiologic evidence — I.M. Lee, C.H. Hennekens, et al. (1995)
• Systematic review and meta-analysis of epidemiological literature evaluating the association between exposure to man-made vitreous fibers and respiratory tract cancers — N. Suder Egnot, S.M. Benson, et al. (2020)
• Lung cancer and exposure to man-made vitreous fibers: results from a pooled case-control study in Germany — H. Pohlabeln, K.H. Jöckel, et al. (2000)
• Cytotoxic and oxidative effects induced by man-made vitreous fibers (MMVFs) in a human mesothelial cell line — D. Cavallo, A. Campopiano, et al. (2004)
• 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)
• Risk of mesothelioma and occupational exposure to asbestos and man-made vitreous fibers: evidence from two case-control studies in Montreal, Canada — J. Pintos, M.E. Parent, et al. (2009)

Browse more research in American Journal of Industrial Medicine, or return to medical research.