SYN-JEM: A Quantitative Job-Exposure Matrix for Five Lung Carcinogens

Our plain-English summary of SYN-JEM: A Quantitative Job-Exposure Matrix for Five Lung Carcinogens, by S. Peters, R. Vermeulen, L. Portengen, et al (The Annals of Occupational Hygiene, 2016).

The study

• Authors: S. Peters, R. Vermeulen, L. Portengen, A. Olsson, B. Kendzia, R. Vincent, B. Savary, J. Lavoué, D. Cavallo, A. Cattaneo, D. Mirabelli, N. Plato, J. Fevotte, B. Pesch, T. Brüning, K. Straif, H. Kromhout
• Journal: The Annals of Occupational Hygiene
• Published: 2016;60(7):795-811
• Cited by: 80 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: The use of measurement data in occupational exposure assessment allows more quantitative analyses of possible exposure-response relations. We describe a quantitative exposure assessment approach for five lung carcinogens (i.e. asbestos, chromium-VI, nickel, polycyclic aromatic hydrocarbons (by its proxy benzo(a)pyrene (BaP)) and respirable crystalline silica). A quantitative job-exposure matrix (JEM) was developed based on statistical modeling of large quantities of personal measurements.

Methods: Empirical linear models were developed using personal occupational exposure measurements (n = 102306) from Europe and Canada, as well as auxiliary information like job (industry), year of sampling, region, an a priori exposure rating of each job (none, low, and high exposed), sampling and analytical methods, and sampling duration. The model outcomes were used to create a JEM with a quantitative estimate of the level of exposure by job, year, and region.

Results: Decreasing time trends were observed for all agents between the 1970s and 2009, ranging from -1.2% per year for personal BaP and nickel exposures to -10.7% for asbestos (in the time period before an asbestos ban was implemented). Regional differences in exposure concentrations (adjusted for measured jobs, years of measurement, and sampling method and duration) varied by agent, ranging from a factor 3.3 for chromium-VI up to a factor 10.5 for asbestos.

Conclusion: We estimated time-, job-, and region-specific exposure levels for four (asbestos, chromium-VI, nickel, and RCS) out of five considered lung carcinogens. Through statistical modeling of large amounts of personal occupational exposure measurement data we were able to derive a quantitative JEM to be used in community-based studies.

© The Author 2016. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

In plain English

This study built SYN-JEM, a job-exposure matrix for five lung carcinogens, with job-, year- and region-specific estimates for four: asbestos, chromium-VI, nickel and respirable crystalline silica. Benzo(a)pyrene data were too few for job- or region-specific estimates. It did not study disease. The authors modelled personal exposure measurements from Europe and Canada, including 27,958 asbestos measurements (1971 to 2009), mostly analysed by phase contrast microscopy. Before asbestos bans, estimated asbestos levels fell by 10.7% per year (95% CI -11.3% to -10.0%). After the bans, the +1.7% yearly trend (95% CI -0.4% to +3.7%) was not statistically significant. The modelled geometric mean ratio for asbestos before versus after the bans was 3.06 (95% CI 2.65 to 3.54). Regional asbestos estimates differed up to 10.5-fold; Central and Eastern European countries were highest. For 1980, the modelled geometric mean for jobs rated high exposed was 0.074 fibres per ml, standardized to an eight-hour shift without a region effect. The highest 1980 job estimate, 0.439 fibres per ml, was for heating, ventilation and refrigeration engineering technicians. The authors concluded that the estimates appear realistic but carry uncertainty.

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. Linear mixed-effects models were applied to existing personal workplace exposure measurements to build a quantitative job-exposure matrix. No health outcomes were studied.
• Who was studied: Personal occupational exposure measurements, not people. They came from the ExpoSYN database for Europe and Canada and covered the 1970s to 2009. There were 27,958 asbestos measurements (1971 to 2009), plus measurements for chromium, nickel, benzo(a)pyrene and respirable crystalline silica. The regions were Canada, Central and Eastern European countries, France, Germany, Italy/Spain, Sweden (with all Nordic countries), the UK and the Netherlands.
• Exposure: Airborne asbestos fibre counts in fibres per ml. More than 95% of samples were analysed by phase contrast microscopy; German measurements were mostly analysed by electron microscopy. Fibre types are not specified. The other agents were chromium-VI, nickel, PAH (measured as benzo(a)pyrene) and respirable crystalline silica. Asbestos exposure was not assigned before 1945, except in Italy, Russia, Canada and the UK.
• Main results:
  • The asbestos time trend after bans was +1.7% per year (95% CI -0.4% to +3.7%), which was not statistically significant. Before bans the trend was -10.7% per year (95% CI -11.3% to -10.0%).
  • The modelled geometric mean ratio for asbestos concentrations before versus after the ban was 3.06 (95% CI 2.65 to 3.54).
  • The ratio between the highest and lowest regional estimate was 10.5 for asbestos and 3.3 for chromium-VI. Regional asbestos ratios were 3.60 for Central and Eastern European countries, 0.34 for the UK, 0.37 for Sweden, and 2.47 for Germany and the Netherlands combined.
  • Measured asbestos levels decreased by 23.1% (95% CI -26.0 to -20.0%) for each hour of increase in sampling duration.
  • For asbestos, the geometric mean ratio for jobs rated low versus high exposed was 0.83 (0.49 to 1.39), which was not statistically significant.
  • Model-based geometric mean asbestos estimates were standardized to an 8-hour shift and given without a region effect. Low exposed jobs were 0.061 fibres per ml in 1980 and 0.004 in 2000. High exposed jobs were 0.074 in 1980 and 0.005 in 2000. The 2000 values assume a ban implemented in 1995.
  • The highest model-based geometric mean asbestos estimate in 1980 was for heating, ventilation, and refrigeration engineering technicians, at 0.439 fibres per ml (0.029 fibres per ml in 2000; 159 measurements). Next were spinners (thread and yarn) at 0.407 fibres per ml. Building insulators (hand) were at 0.244 fibres per ml.
  • Time trends decreased for all five agents, ranging from -1.2% per year for benzo(a)pyrene and nickel to -10.7% for asbestos before bans. Benzo(a)pyrene data were too few for job- or region-specific estimates.
• The authors' conclusion: The authors concluded that SYN-JEM estimates appear realistic and point toward a valid method for quantitative occupational exposure assessment in general-population studies, although with uncertainty around the estimates. Job- and region-specific estimates were possible for four of the five agents.
• Limitations the authors state:
  • Electron microscopy was used only in Germany, so differences between analytical methods could not be separated from regional differences. German asbestos data were also mostly taken after the ban, which may have contributed to the higher estimate for Germany.
  • A single overall time trend was applied to each agent, which may have under- or overestimated exposure in particular industries.
  • The contrast between jobs rated low and high exposed was much lower than generally assumed. The authors suggest that worst-case monitoring of low exposed jobs may have caused this.
  • Residual variance (between plants, between workers and from day to day) was the largest component for all agents, and no information was available to explain it.
  • The measurement strategy was unknown for two-thirds of the asbestos measurements.
  • Not all measurement-strategy factors could be adjusted for, so regional estimates carry considerable uncertainty and should be interpreted with caution.
  • The limited number of benzo(a)pyrene measurements did not allow job- and region-specific estimates for PAH.

Topics

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

Medical terms in this study, explained in our Lexicon: Occupational Exposure, Crystalline.

Related studies

• Development of an exposure measurement database on five lung carcinogens (ExpoSYN) for quantitative retrospective occupational exposure assessment — S. Peters, R. Vermeulen, et al. (2012)
• Lung Cancer Risks Associated with Occupational Exposure to Pairs of Five Lung Carcinogens: Results from a Pooled Analysis of Case-Control Studies (SYNERGY) — A. Olsson, L. Bouaoun, et al. (2024)
• Comparison of exposure assessment methods for occupational carcinogens in a multi-centre lung cancer case-control study — S. Peters, R. Vermeulen, et al. (2011)
• Exposure-Response Analyses of Asbestos and Lung Cancer Subtypes in a Pooled Analysis of Case-Control Studies — A.C. Olsson, R. Vermeulen, et al. (2017)
• Comparison of expert and job-exposure matrix-based retrospective exposure assessment of occupational carcinogens in The Netherlands Cohort Study — N.S. Offermans, R. Vermeulen, et al. (2012)
• Variations in exposure to carcinogens among shift workers and non-shift workers — S. El-Zaemey, R.N. Carey (2019)

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