Non-Malignant Respiratory Illnesses in Association with Occupational Exposure to Asbestos and Other Insulating Materials: Findings from the Alberta Insulator Cohort

Our plain-English summary of Non-Malignant Respiratory Illnesses in Association with Occupational Exposure to Asbestos and Other Insulating Materials: Findings from the Alberta Insulator Cohort, by S. Moitra, A. Farshchi Tabrizi, K. Idrissi Machichi, et al (International Journal of Environmental Research and Public Health, 2020).

The study

• Authors: S. Moitra, A. Farshchi Tabrizi, K. Idrissi Machichi, S. Kamravaei, N. Miandashti, L. Henderson, M. Mukherjee, F. Khadour, M.T. Naseem, P. Lacy, L. Melenka
• Journal: International Journal of Environmental Research and Public Health
• Published: 2020;17(19)
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Many insulating materials are used in construction, although few have been reported to cause non-malignant respiratory illnesses. We aimed to investigate associations between exposures to insulating materials and non-malignant respiratory illnesses in insulators. In this cross-sectional study, 990 insulators (45 ± 14 years) were screened from 2011-2017 in Alberta. All participants underwent pulmonary function tests and chest radiography. Demographics, work history, and history of chest infections were obtained through questionnaires. Chronic obstructive pulmonary disease (COPD) was diagnosed according to established guidelines. Associations between exposures and respiratory illnesses were assessed by modified Poisson regression. Of those screened, 875 (88%) were males. 457 (46%) participants reported having ≥ 1 chest infection in the past 3 years, while 156 (16%) were diagnosed with COPD. In multivariate models, all materials (asbestos, calcium silicate, carbon fibers, fiberglass, and refractory ceramic fibers) except aerogels and mineral fibers were associated with recurrent chest infections (prevalence ratio [PR] range: 1.18-1.42). Only asbestos was associated with COPD (PR: 1.44; 95% confidence interval [CI]: 1.01, 2.05). Therefore, occupational exposure to insulating materials was associated with non-malignant respiratory illnesses, specifically, recurrent chest infections and COPD. Longitudinal studies are urgently needed to assess the risk of exposure to these newly implemented insulation materials.

In plain English

This cross-sectional study looked at 990 union insulators in Edmonton, Alberta, screened in a voluntary workplace health program from 2011 to 2017. Most (88%) were men, with an average age of 45. Workers answered questionnaires about their work and the insulating materials they had ever been exposed to, and had breathing tests. Over half (55%) reported ever being exposed to asbestos. Overall, 46% reported at least one chest infection in the past three years; 16% had COPD and 4% had asthma. After adjusting for sex, age, education and smoking, asbestos, calcium silicate, carbon fibers, fiberglass and refractory ceramic fibers were each linked with more chest infections. Aerogels were not, and mineral fibers showed only a marginal link that was not statistically significant. Asbestos was the only material linked with more COPD (prevalence ratio 1.45, 95% confidence interval 1.01 to 2.05). No material was linked with asthma in single-material models; the authors called an inverse mineral fiber link in a combined model inconsistent. The authors concluded that exposure to insulation materials was associated with more chest infections and, to a lesser degree, COPD. They noted that this design cannot show cause and that exposures were not measured.

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: Cross-sectional study of insulators screened in a workplace health surveillance program, using questionnaires and breathing tests (spirometry), analysed with modified Poisson regression
• Who was studied: 990 unionized insulators (88% male, mean age 45) from Local 110 Heat and Frost Insulators and Allied Workers Union, Edmonton, Alberta, Canada, screened 2011 to 2017. 1043 registered, and 53 trainees with no exposure history were excluded.
• Exposure: Self-reported ever-exposure at work to asbestos (55%), aerogels (40%), calcium silicate (89%), carbon fibers (60%), fiberglass (86%), mineral fibers (96%) and refractory ceramic fibers (64%). Asbestos fiber types were not specified, and exposure levels were not measured.
• Main results:
  • Among all 990 insulators, 457 (46%) reported at least one chest infection in the past 3 years. 16% were diagnosed with COPD and 4% with asthma.
  • In adjusted single-material models, asbestos, calcium silicate, carbon fibers, fiberglass and refractory ceramic fibers were each associated with recurrent chest infections (prevalence ratio range 1.18 to 1.42). Aerogels and mineral fibers were not significantly associated.
  • Mineral fiber exposure was marginally associated with chest infections. The authors described this as clinically important but not statistically significant.
  • In the single-material model, insulators exposed to asbestos had a higher prevalence of COPD (prevalence ratio 1.45; 95% confidence interval 1.01 to 2.05).
  • Calcium silicate exposure showed an inverse association with COPD (prevalence ratio 0.57; confidence interval 0.41 to 0.80). The authors attributed this to fewer COPD cases among exposed workers in the oldest age quarter.
  • When all materials were put in one model, only asbestos and refractory ceramic fibers remained associated with chest infections.
  • When all materials were put in one model, the asbestos association with COPD persisted (prevalence ratio 1.55; 95% confidence interval 1.08 to 2.22).
  • After further adjustment for use of personal protective equipment, only asbestos was consistently associated with chest infections and COPD.
  • In single-material models, no occupational exposure was associated with asthma.
  • In the combined (multi-exposure) model, mineral fibers were inversely associated with asthma (prevalence ratio 0.22; 95% confidence interval 0.06 to 0.80). The authors called this inconsistent with the single-exposure model.
• The authors' conclusion: The authors concluded that chronic occupational exposure to insulation materials in insulators is associated with an increased prevalence of chest infections and, to a lesser degree, COPD.
• Limitations the authors state:
  • Cross-sectional design, so causal association could not be determined
  • Actual workplace exposures were not measured
  • Exposure levels and durations could not be measured or recalled, so no cumulative exposure index could be built
  • Information on protective equipment was inadequate, so its effectiveness could not be assessed
  • Information on other workplace exposures (vapors, dust, gas, fumes) and other possible confounders was not available

Topics

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

Medical terms in this study, explained in our Lexicon: Occupational Exposure, Insulator, Pulmonary Function Test (PFT), Work History, COPD, Silicate, Mineral Fiber, confidence interval.

Related studies

• Exposure to insulating materials and risk of coronary artery diseases: a cross-sectional study — S. Moitra, A.F. Tabrizi, et al. (2023)
• Asbestos, asbestosis, smoking, and lung cancer. New findings from the North American insulator cohort — S.B. Markowitz, S.M. Levin, et al. (2013)
• Under-reporting of compensable mesothelioma in Alberta — M.W. Cree, M. Lalji, et al. (2009)
• Lung health among boilermakers in Edmonton, Alberta — P.A. Hessel, L.S. Melenka, et al. (1998)
• Lung health among plumbers and pipefitters in Edmonton, Alberta — P.A. Hessel, L.S. Melenka, et al. (1998)
• Non-malignant occupational respiratory diseases in Germany in comparison with those of other countries — X. Baur, U. Latza (2005)

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