Developing a company-specific job exposure matrix for the Asbest Chrysotile Cohort Study

Our plain-English summary of Developing a company-specific job exposure matrix for the Asbest Chrysotile Cohort Study, by E. Feletto, E.V. Kovalevskiy, S.J. Schonfeld, et al (Occupational and Environmental Medicine, 2022).

The study

• Authors: E. Feletto, E.V. Kovalevskiy, S.J. Schonfeld, M. Moissonnier, A. Olsson, S.V. Kashanskiy, E. Ostroumova, I.V. Bukhtiyarov, J. Schüz, H. Kromhout
• Journal: Occupational and Environmental Medicine
• Published: 2022;79(5):339-346
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objectives: Exposure assessment for retrospective industrial cohorts are often hampered by limited availability of historical measurements. This study describes the development of company-specific job-exposure matrices (JEMs) based on measurements collected over five decades for a cohort study of 35 837 workers (Asbest Chrysotile Cohort Study) in the Russian Federation to estimate their cumulative exposure to chrysotile containing dust and fibres.

Methods: Almost 100 000 recorded stationary dust measurements were available from 1951-2001 (factories) and 1964-2001 (mine). Linear mixed models were used to extrapolate for years where measurements were not available or missing. Fibre concentrations were estimated using conversion factors based on side-by-side comparisons. Dust and fibre JEMs were developed and exposures were allocated by linking them to individual workers' detailed occupational histories.

Results: The cohort covered a total of 515 355 employment-years from 1930 to 2010. Of these individuals, 15% worked in jobs not considered professionally exposed to chrysotile. The median cumulative dust exposure was 26 mg/m3 years for the entire cohort and 37.2 mg/m3 years for those professionally exposed. Median cumulative fibre exposure was 16.4 fibre/cm3 years for the entire cohort and 23.4 fibre/cm3 years for those professionally exposed. Cumulative exposure was highly dependent on birth cohort and gender. Of those professionally exposed, women had higher cumulative exposures than men as they were more often employed in factories with higher exposure concentrations rather than in the mine.

Conclusions: Unique company-specific JEMs were derived using a rich measurement database that overlapped with most employment-years of cohort members and will enable estimation of quantitative exposure-response.

© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

In plain English

The authors built job-exposure matrices (tables of estimated yearly exposure by job) for the Asbest Chrysotile Cohort Study. The cohort was 35 837 workers employed at least 1 year between 1975 and 2010 at the JSC Uralasbest chrysotile mine and factories in Asbest, Russian Federation. Estimates used fixed-location dust measurements from 1951 (factories) and 1964 (mine) through 2001, and later years were extrapolated. Fibre levels were calculated from dust, and models filled other missing years. The paper reported exposure estimates, not disease rates. Fifteen per cent of workers only ever held jobs not considered professionally exposed. Among professionally exposed workers, median cumulative exposure was 37.2 mg/m3 years for dust and 23.4 fibre/cm3 years for fibres. Exposed women had higher medians than exposed men, which the authors linked to more women working in the factories, where levels were higher. Median work duration and cumulative exposure fell across later birth and hiring groups. The authors noted limitations including fixed rather than personal sampling, modelled data, and fibre conversion from only three sets of parallel measurements. They said the matrices will be used to study cancer mortality.

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: Exposure assessment study: development of company-specific job-exposure matrices for an existing historic (retrospective) cohort study
• Who was studied: 35 837 workers who worked at least 1 year between 1975 and 2010 in the factories and mine of JSC Uralasbest, Asbest, Southern Urals, Russian Federation; 22 463 men and 13 374 women
• Exposure: Chrysotile-containing dust and chrysotile fibres. Dust came from almost 100 000 stationary dust measurements, recorded from 1951 (factories) and 1964 (mine and external rail). Measurements by sampling point were used up to and including 2001, and exposure from 2002 onwards was extrapolated. Fibres were estimated from dust using conversion factors.
• Main results:
  • 15% of cohort members worked, for their entire occupational history, only in jobs recorded as not professionally exposed to chrysotile
  • The factory matrix used 91 402 dust measurements covering 88% of 167 509 professionally exposed employment-years. The text reports that the mine/external rail matrix used 8100 measurements covering 76% of 227 458.
  • Median cumulative dust exposure was 26 mg/m3 years for the entire cohort and 37.2 mg/m3 years for professionally exposed workers. The corresponding fibre values were 16.4 and 23.4 fibre/cm3 years.
  • Exposed women versus exposed men had median cumulative dust exposure of 49.4 vs 31.4 mg/m3 years and fibre exposure of 32.9 vs 19.3 fibre/cm3 years
  • The authors attributed women's higher cumulative exposure to most exposed women working in the factories, where concentrations were higher than in the mine and external rail
  • Among exposed workers, median cumulative dust exposure was 53.4 mg/m3 years for those who worked only in the factories, 41.4 for those who worked in both areas, and 25.9 for those who worked only in the mine or external rail
  • Median work duration and median cumulative dust and fibre exposures decreased by birth cohort and by year of first job period
  • The correlation between cumulative dust and cumulative fibre exposure was 0.77. Average intensity correlated at 0.70.
• The authors' conclusion: The authors concluded that the matrices will be applied in exposure-response analyses of chrysotile dust and fibre concentrations and cancer mortality within the cohort
• Limitations the authors state:
  • Measurements came from stationary samplers, which may overestimate or underestimate exposure compared with personal samplers
  • Missing exposure data required modelling (interpolation and extrapolation) for a total of 19% of employment-years
  • Dust-to-fibre conversion was based on only three sets of relatively recent parallel measurements
  • A 15 mg/m3 cap was used in the fibre conversion, affecting 8% of monthly concentrations
  • Possible exposure misclassification, especially among the 15% whose workplaces were not systematically monitored

Topics

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

Medical terms in this study, explained in our Lexicon: Chrysotile, Cohort Study, Cumulative Exposure.

Related studies

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• Cancer mortality in chrysotile miners and millers, Russian Federation: main results (Asbest Chrysotile Cohort-Study) — J. Schüz, E. Kovalevskiy, et al. (2024)
• Occupational cohort study of current and former workers exposed to chrysotile in mine and processing facilities in Asbest, the Russian Federation: Cohort profile of the Asbest Chrysotile Cohort study — J. Schüz, I. Bukhtiyarov, et al. (2020)
• Comparison of Two Information Sources for Cause-of-Death Follow-up in the Russian Federation: The Asbest Chrysotile Cohort Study — J. Schüz, E. Kovalevskiy, et al. (2020)
• A retrospective cohort study of cancer mortality in employees of a Russian chrysotile asbestos mine and mills: study rationale and key features — J. Schüz, S.J. Schonfeld, et al. (2013)
• A comparison of parallel dust and fibre measurements of airborne chrysotile asbestos in a large mine and processing factories in the Russian Federation — E. Feletto, S.J. Schonfeld, et al. (2017)

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