A comparison of parallel dust and fibre measurements of airborne chrysotile asbestos in a large mine and processing factories in the Russian Federation

Our plain-English summary of A comparison of parallel dust and fibre measurements of airborne chrysotile asbestos in a large mine and processing factories in the Russian Federation, by E. Feletto, S.J. Schonfeld, E.V. Kovalevskiy, et al (International Journal of Hygiene and Environmental Health, 2017).

The study

• Authors: E. Feletto, S.J. Schonfeld, E.V. Kovalevskiy, I.V. Bukhtiyarov, S.V. Kashanskiy, M. Moissonnier, K. Straif, J. Schüz, H. Kromhout
• Journal: International Journal of Hygiene and Environmental Health
• Published: 2017;220(5):857-868
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Introduction: Historic dust concentrations are available in a large-scale cohort study of workers in a chrysotile mine and processing factories in Asbest, Russian Federation. Parallel dust (gravimetric) and fibre (phase-contrast optical microscopy) concentrations collected in 1995, 2007 and 2013/14 were used to determine if dust to fibre conversion factors can be estimated.

Materials/subjects And Methods: Daily medians of multiple parallel dust and fibre concentrations by sampling points were used to derive fibre to dust ratios. Applying linear mixed models, we estimated best linear unbiased predictions for the fibre to dust ratios.

Results And Discussion: A total of 620 daily median fibre to dust ratios were derived. In the factories, modelled ratios varied by unit, increasing along the stages of asbestos enrichment as expected. In the mine, ratios were higher in winter compared to summer. Overall, the ratios showed a strong negative dependency on dust concentration.

Conclusions: Our study shows that dust to fibre conversion is possible by unit but extrapolations are needed. The patterns for exposure by dust and fibre will be similar but estimated fibre levels will show less contrast due to the conversion factor being smaller at higher dust concentrations.

Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.

In plain English

This study used air measurements from the Uralasbest chrysotile asbestos open-pit mine and factories in Asbest, Russian Federation. The aim was to test converting historic dust measurements into fibre concentrations for a workers' cohort study. Dust (by weight) and fibres (by phase-contrast microscope) were sampled side by side at fixed points: in two factories in 1995 and 2007, one factory in 2013/14, and the mine in 2007 and 2013/14. This gave 620 daily fibre-to-dust ratios for statistical modelling. Factory ratios differed by unit, rising from crushing and sorting through enrichment to final product. Factory ratios in 1995 and 2007 were higher than in 2013/14 by 48% and 36%, both statistically significant. Mine ratios were 67% higher in winter than in summer, though the authors cautioned that all winter mine measurements came from 2013/14. Each 1 mg/m3 rise in dust lowered the ratio by 9% in the factories and 20% in the mine. The authors concluded that conversion is possible below 15 mg/m3 of dust, if done by unit and adjusted for dust level. They noted that samples came only from two factories and recent years.

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 measurement study comparing parallel stationary dust and fibre measurements, analysed with linear mixed models (no participant-level data)
• Who was studied: Sampling points in the open-pit mine and in Factory 4 and Factory 6 of Uralasbest, Asbest, Russian Federation. Samples came from 1995, 2007 and 2013/14, giving 620 daily median fibre to dust ratios: 95 from the mine and 525 from the factories. There were no mine data for 1995, and only Factory 6 was sampled in 2013/14 because Factory 4 closed in 2010.
• Exposure: Airborne chrysotile asbestos dust, measured gravimetrically in mg/m3, and fibres, counted by phase contrast optical microscopy in f/cm3. Measurements were taken at mine units (mining, mine dump, drilling, rail transport) and at factory units (crushing and sorting, enrichment, final product packaging, laboratory).
• Main results:
  • The overall fibre to dust ratio in the factories was 1.15 in 1995, 0.98 in 2007 and 0.66 in 2013/14. In the mine, the median ratio was 0.92 in 2007 and 1.20 in 2013/14.
  • In the factories, ratios depended on unit and increased as the enrichment process progressed from crushing and sorting through enrichment to final product. The between-unit variance approached statistical significance in the factories (p = 0.06) and was not statistically significant in the mine (p = 0.39).
  • In the factories, ratios from 1995 and 2007 were 48% and 36% higher than in 2013/14, both statistically significant.
  • In the mine, ratios from 2007 were 31% higher than in 2013/14, with the difference approaching statistical significance (p = 0.06).
  • In the mine, winter ratios were 67% higher than summer ratios (p = 0.01). In the factories there was no statistical difference between summer and winter.
  • For every 1 mg/m3 increase in dust concentration, the fibre to dust ratio decreased by 9% in the factories and by 20% in the mine.
  • A sensitivity analysis using daily mean instead of daily median concentrations gave very similar results.
• The authors' conclusion: The authors concluded that converting asbestos dust to fibre concentrations is possible for dust exposures under 15 mg/m3, but that it should be done at the unit level with adjustment for the actual dust concentration. They also concluded that estimated fibre levels will show less contrast than dust levels, because the conversion factor is smaller at higher dust concentrations.
• Limitations the authors state:
  • Parallel samples were available for only two factories and only from recent years of production, so applying them to dust measured 40 to 60 years earlier will be challenging.
  • Applying the model at dust levels above 15 mg/m3, which occurred before 1960, would give unrealistically low fibre estimates.
  • Ratios were not constant over time, and the model cannot account for changes in mining and processing practices or in the asbestos content of the ore.
  • The seasonal difference in the mine should be interpreted cautiously, because all winter mine measurements came from 2013/14.
  • The parallel dust and fibre samples did not always run for the same length of time.

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.

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• Tobacco smoking among chrysotile asbestos workers in Asbest in the Russian Federation — A. Olsson, E.V. Kovalevskiy, et al. (2020)
• Cancer mortality in chrysotile miners and millers, Russian Federation: main results (Asbest Chrysotile Cohort-Study) — J. Schüz, E. Kovalevskiy, et al. (2024)
• 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)
• 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)
• Airborne concentrations of chrysotile asbestos in serpentine quarries and stone processing facilities in Valmalenco, Italy — A. Cattaneo, A. Somigliana, et al. (2012)

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