Co-exposure to refractory ceramic fibres and asbestos and risk of pleural mesothelioma

Our plain-English summary of Co-exposure to refractory ceramic fibres and asbestos and risk of pleural mesothelioma, by A. Lacourt, M. Rinaldo, C. Gramond, et al (The European Respiratory Journal, 2014).

The study

• Authors: A. Lacourt, M. Rinaldo, C. Gramond, S. Ducamp, A. Gilg Soit Ilg, M. Goldberg, J.C. Pairon, P. Brochard
• Journal: The European Respiratory Journal
• Published: 2014;44(3):725-33
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The aim of this study was to investigate the hypothesis of an increased risk of pleural mesothelioma due to co-exposure to asbestos and refractory ceramic fibres (RCF) compared to asbestos exposure alone. Males were selected from a French case-control study conducted in 1987-1993 and from the French National Mesothelioma Surveillance Program in 1998-2006. Two population controls were frequency matched to each case by year of birth. Complete job histories were collected and occupational asbestos and RCF exposures were assessed using job exposure matrices. The dose-response relationships for asbestos exposure were estimated from an unconditional logistic regression model in subjects exposed to asbestos only (group 1) and subjects exposed to both asbestos and RCF (group 2). A total of 988 cases and 1125 controls ever-exposed to asbestos were included. A dose-response relationship was observed in both groups but it was stronger in group 2. In comparison with subjects exposed at the minimum value of the cumulative index of exposure, the odds ratio was 2.6 (95% CI 1.9-3.4) for subjects exposed to 75 fibres · mL(-1) · year(-1) in group 1 increasing to 12.4 (95% CI 4.6-33.7) in group 2. Our results suggest that the pleural carcinogenic effect of occupational asbestos exposure may be modified by additional exposure to RCF.

©ERS 2014.

In plain English

This French case–control study examined whether men exposed at work to both asbestos and refractory ceramic fibres (RCF) had a different risk of pleural mesothelioma than men exposed to asbestos alone. The analysis included 988 male cases and 1125 male controls, all occupationally exposed to asbestos. Exposures were estimated from job histories using job exposure matrices. Of these men, 127 cases (12.8%) and 92 controls (8.2%) had also been exposed to RCF. Men exposed to both had a higher risk than men exposed to asbestos only (odds ratio 1.6, 95% CI 1.2–2.2). Cases in the co-exposed group also had more asbestos exposure. Risk rose with cumulative asbestos exposure in both groups. At an index of 75 fibres per mL per year, compared with the lowest exposure, the odds ratio was 2.6 (95% CI 1.9–3.4) for asbestos only and 12.4 (95% CI 4.6–33.7) for co-exposure. The authors concluded that the dose–response relationship was stronger with RCF co-exposure and that further investigation is needed. They noted that the co-exposed group was small, its confidence intervals were wide, and the fibre types were 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: case–control study using pooled French data; analysis limited to asbestos-exposed men, comparing those exposed to asbestos only with those exposed to both asbestos and RCF
• Who was studied: 988 male cases of pleural mesothelioma and 1125 male controls, all occupationally exposed to asbestos, in France. The asbestos-exposed men were drawn from a dataset of 1199 male cases and 2379 male controls. Cases came from an earlier case–control study (1987–1993) and the French National Mesothelioma Surveillance Program (1998–2006). Population controls were frequency matched by sex and year of birth.
• Exposure: occupational asbestos and refractory ceramic fibre (RCF) exposure, estimated from complete job histories using two job exposure matrices and expressed as a cumulative index of exposure; asbestos fibre types were not known (the authors state chrysotile seems to have been the most common type used in France)
• Main results:
  • Among asbestos-exposed subjects, 127 cases (12.8%) and 92 controls (8.2%) were also exposed to RCF
  • Subjects exposed to both asbestos and RCF had a significantly higher risk of pleural mesothelioma than subjects exposed to asbestos only: OR 1.6 (95% CI 1.2–2.2)
  • Cases in the co-exposed group had more asbestos exposure than cases exposed to asbestos only: 54.3% had definite asbestos exposure versus 37.4%, and they had a greater cumulative index and a longer duration of asbestos exposure
  • In the asbestos-only group, compared with the minimum cumulative index of exposure, the OR was 1.1 (95% CI 1.0–1.1) at 1 and 2.6 (95% CI 1.9–3.4) at 75 fibres per mL per year
  • In the asbestos-plus-RCF group, compared with the minimum cumulative index of exposure, the OR was 1.2 (95% CI 1.1–1.4) at 1 and 12.4 (95% CI 4.6–33.7) at 75 fibres per mL per year
  • The shape and the size of the dose–response curves differed between the two groups
  • Sensitivity analyses using different definitions of an exposed job gave similar results
• The authors' conclusion: The authors concluded that the dose–response relationship between occupational asbestos exposure and pleural mesothelioma is stronger in the presence of occupational co-exposure to RCF, and that further investigation is needed to confirm and understand this effect modification.
• Limitations the authors state:
  • In the co-exposed group, confidence intervals were large and estimates were based on few subjects
  • No information on the type of RCF used
  • No information on the types of asbestos used
  • Cases and controls came from different sources, which could have introduced bias
  • Job exposure matrices produce misclassification, so some odds ratios may have been underestimated
  • The authors could not assess the effect of the order in which asbestos and RCF exposures occurred

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Asbestos Exposure, Case-Control Study, Mesothelioma, Dose-response relationship, Odds Ratio, Carcinogenic.

Related studies

• Health effects of refractory ceramic fibres: scientific issues and policy considerations — L.R. Glass, R.C. Brown, et al. (1995)
• Risk analysis for mortality from respiratory tumors in a cohort of refractory ceramic fiber workers — A.M. Walker, L.D. Maxim, et al. (2002)
• Clinico-pathological features and somatic gene alterations in refractory ceramic fibre-induced murine mesothelioma reveal mineral fibre-induced mesothelioma identities — P. Andujar, C. Lecomte, et al. (2007)
• Exposure to refractory ceramic fibres in the metal industry — M. Linnainmaa, J. Kangas, et al. (2007)
• Refractory ceramic fiber exposure and pleural plaques — J. Lockey, G. Lemasters, et al. (1996)
• Occupational and non-occupational attributable risk of asbestos exposure for malignant pleural mesothelioma — A. Lacourt, C. Gramond, et al. (2014)

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