Historical Asbestos Measurements in Denmark-A National Database

Our plain-English summary of Historical Asbestos Measurements in Denmark-A National Database, by A.S. Fonseca, A.K. Jørgensen, B.X. Larsen, et al (International Journal of Environmental Research and Public Health, 2022).

The study

• Authors: A.S. Fonseca, A.K. Jørgensen, B.X. Larsen, M. Moser-Johansen, E.M. Flachs, N.E. Ebbehøj, J.H. Bønløkke, T.O. Østergaard, J. Bælum, D.L. Sherson, V. Schlünssen, H.W. Meyer, K.A. Jensen
• Journal: International Journal of Environmental Research and Public Health
• Published: 2022;19(2)
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objectives: Due to the long lag-time for health outcomes, historical asbestos exposure measurements are valuable to support assessments of associated occupational health effects, and also to assess time trends and effects of preventive measures.

Methods: Different sources of stored data were collated, assessed and refined to create a harmonized database on historical asbestos fibre concentrations measured in specific work tasks and different industries. The final database contains 9236 asbestos measurements from Danish workplaces collected from 1971 to 1997.

Results: The geometric mean of asbestos concentrations in different occupations and tasks ranged from 0.003 to 35 fibres cm-3. Highest concentrations were registered during handling of asbestos products in the construction services during the period 1981-1997. Although all the measured asbestos exposures without the use of respiratory equipment by the worker in the period of 1971-1997 exceeded the current 8-h time-weighted average exposure limit of 0.1 fibres cm-3, the majority of samples collected in the earlier period of 1971 to 1980 did not exceed the exposure limit of 2 fibres cm-3, which was in place at the time. All exposure data obtained from 1980 and onwards were found to be one seventh of the mean fibre concentrations in the previous measurement period. The impact of time shows a clear exponentially decreasing trend-line.

Conclusions: Despite limitations in coverage of different occupations and tasks associated with the inventoried historical asbestos measurements, the data are helpful to identify specific work scenarios within an industry, where relatively high asbestos exposure levels may still occur or have occurred from 1971 to 1997.

In plain English

This study compiled Danish workplace measurements of airborne asbestos fibres from 1971 to 1997 into a national database. Of 9236 records from four archive sources, 5869 had enough information for analysis. Most came from factories making asbestos cement products and automotive materials such as brakes. In 1971 to 1980, manufacturing medians without respiratory protection were 0.6 to 2.2 fibres per cubic centimetre, maximum 103. Geometric means from 1980 onwards were seven-fold lower in several job categories. The authors found the highest concentrations during active handling of asbestos products in construction. Hospital cement floor removal gave 3.3 to 92 fibres per cubic centimetre, measured outside respirators. Because most samples covered short tasks, the authors compared them only roughly with 8-hour average limits. On that basis, all situations measured without or outside respirators had geometric means above today's Danish limit of 0.1. Most 1971 to 1980 samples in automotive manufacturing and supervision were below the limit of 2 then in force. Most records lacked sampling-method details. The authors concluded the data identify scenarios where relatively high exposures occurred and might still occur in construction.

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: Compilation and analysis of historical workplace air measurements of asbestos fibres into a national exposure database
• Who was studied: 9236 asbestos measurement records from Danish workplaces, 1971 to 1997, of which 5869 met minimum data-quality criteria. Most were from asbestos cement and automotive (e.g., brake) manufacturing. Others came from construction, railways, power plants, hospitals, schools and other settings.
• Exposure: Airborne asbestos fibre concentrations (fibres per cubic centimetre), mostly personal breathing-zone samples. These were taken during manufacturing of fibre cement plates (eternit), insulation plates and automotive materials, and during handling, removal, warehouse, maintenance, supervision and cleaning tasks. Fibre types were not distinguished in the measurements.
• Main results:
  • Manufacturing workers without respiratory protection, 1971 to 1980: median fibre concentrations of 0.6 to 2.2 fibres per cubic centimetre, with maximum levels up to 103 fibres per cubic centimetre.
  • In 1981 to 1997, median exposure fell by 79% in cement plate manufacturing and by 84% in automotive materials manufacturing.
  • Data from 1980 onwards had seven-fold lower geometric mean concentrations than the earlier period. This applied to manufacturing, cleaning, supervision and warehouse activities in the cement and automotive industries.
  • Airborne fibre concentrations were highest during active handling of asbestos products in construction services.
  • Removal and scraping of cement floors in a hospital: 3.3 to 92 fibres per cubic centimetre, measured outside the respirator.
  • In 1971 to 1980, geometric means without respiratory protection were 1.1 to 1.9 fibres per cubic centimetre in manufacturing, 0.8 in cleaning, and 0.7 in warehouse activities in the asbestos cement industry.
  • Geometric means in all situations measured without or outside respirators, 1971 to 1997, exceeded the current 8-hour limit of 0.1 fibres per cubic centimetre. This was a rough comparison, because it assumed that short-task samples represented 8-hour averages.
  • Most samples from 1971 to 1980 in automotive component manufacturing and in supervision and inspection tasks were below the limit of 2 fibres per cubic centimetre in place at the time.
  • During dismantling of pipe insulation in a hospital boiler room in 1987, concentrations measured inside workers' respirators were below 0.06 fibres per cubic centimetre. The authors described this as a 98.6% reduction.
  • Without respiratory protection, the lowest exposures were among maintenance workers (geometric mean below 0.8 fibres per cubic centimetre) and supervision and inspection workers (below 1). Office work was below 0.04.
  • A model fitted to the asbestos cement and automotive manufacturing data showed a downward trend in concentrations over time.
• The authors' conclusion: The authors concluded that, despite its limitations, the database identified specific work scenarios where relatively high asbestos exposure levels occurred and might still occur in the construction sector during repair, renovation or demolition. They also concluded it can support historical health-effect and epidemiological assessments.
• Limitations the authors state:
  • For 44.6% of personal measurements it was not stated whether a respirator was used, or whether sampling was inside or outside the mask.
  • Nearly all datasets lacked information on sampling technique and fibre counting. The likely counting method (phase contrast microscopy) cannot tell asbestos from non-asbestos fibres.
  • Samples covered short tasks of 6 to 165 minutes, so only rough comparisons with 8-hour or 15-minute limits were possible.
  • Most data came from two large industries and from regulatory checks. These likely reflect the dustiest tasks and would overestimate exposure if applied to whole workforces.
  • Companies may have influenced results by optimizing tasks, cleaning and ventilation on measurement days.
  • Data before 1980 were scarce, and the scattered data introduced uncertainty into the identification and modelling of time trends.
  • In most occupational categories outside the two main manufacturing industries, only a few measurements were available.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Time-Weighted Average (TWA).

Related studies

• A total sample preparation method for the measurement of airborne asbestos and other fibers by optical and electron microscopy — N. Kohyama, S. Kurimori (1996)
• Development of an exposure measurement database on five lung carcinogens (ExpoSYN) for quantitative retrospective occupational exposure assessment — S. Peters, R. Vermeulen, et al. (2012)
• Colorectal cancer in asbestos cement workers in Denmark — E. Raffn, E. Villadsen, et al. (1996)
• Historical state of knowledge of the health risks of asbestos posed to seamen on merchant ships — D.G. Dodge, B.D. Beck (2016)
• A comparison of fibre counting across three European national proficiency testing schemes — A.D. Jones, M.C. Arroyo, et al. (2005)
• Evaluation of bystander exposures to asbestos in occupational settings: a review of the literature and application of a simple eddy diffusion model — E.P. Donovan, B.L. Donovan, et al. (2011)

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