Exploring the usefulness of occupational exposure registries for surveillance: the case of the Ontario Asbestos Workers Registry (1986-2012)

Our plain-English summary of Exploring the usefulness of occupational exposure registries for surveillance: the case of the Ontario Asbestos Workers Registry (1986-2012), by A.J. Koné Pefoyo, L. Genesove, K. Moore, et al (Journal of Occupational and Environmental Medicine, 2014).

The study

• Authors: A.J. Koné Pefoyo, L. Genesove, K. Moore, A. Del Bianco, D. Kramer
• Journal: Journal of Occupational and Environmental Medicine
• Published: 2014;56(10):1100-10
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objective: The ongoing presence of asbestos in products used across workplaces in Canada reinforces the importance of occupational exposure surveillance. This study evaluates the usefulness of the Ontario Asbestos Workers Registry.

Methods: The study includes 30,829 workers aged 15 to 80 years. Researchers reported on the data quality and analyzed the proportions of workers exposed by industry, and standardized rates by geographic areas and over time.

Results: The incidence of exposure started to decrease around 1990; but about 2000 workers were still exposed annually until 2006. Results showed large geographical disparities. Unexpectedly, workers from industries other than construction reported exposure.

Conclusions: The Ontario Asbestos Workers Registry is a useful but challenging source of information for the surveillance of asbestos exposure in Ontario. The registry could benefit from well-defined surveillance objectives, a clear exposure definition, systematic enforcement, regular data analyses, and results dissemination.

In plain English

This study evaluated whether Ontario's Asbestos Workers Registry, where employers report exposed construction and repair workers, is useful for tracking exposure. After data checks, the authors analyzed 30,829 workers aged 15 to 80 reported exposed from 1934 to June 2012. From 1986 to June 2012, 26,704 workers were newly reported exposed. New exposures began falling around 1990, but about 2000 workers were still exposed yearly until 2006. In 2011, 9.9 per 100,000 Ontario workers were reported exposed. Age-standardized exposure incidence over 1986 to 2012 ranged from 4.7 per 100,000 people in Leeds, Grenville, and Lanark District Health Unit to 2954.4 in Lambton. Construction workers were reported most, but manufacturing and educational services workers also appeared. The authors found many data errors and signs of underreporting: only 12 of 36 identified asbestos removal companies were registered. The highest mesothelioma rates were in areas with high reported exposure, such as Lambton and Hamilton, but some areas reporting few exposed workers had high rates; no definite link was found. The authors concluded the registry is useful but challenging and needs improvement before guiding policy.

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: Evaluation of an occupational exposure registry: data-quality checks, descriptive analysis of registry records by time, area and industry, and an exploratory ecological comparison with mesothelioma rates
• Who was studied: Workers recorded in the Ontario Asbestos Workers Registry (Ontario, Canada). The original data held more than 87,000 entries for 33,011 workers. The final sample was 30,829 workers aged 15 to 80 with exposures reported from 1934 to June 2012.
• Exposure: Occupational asbestos exposure in type 2 or type 3 operations (including removal, enclosure, breaking, cleaning or application of asbestos-containing material), measured as the number of workers and the hours reported. No fiber types are specified.
• Main results:
  • Between 1986 and June 2012, 26,704 workers were newly exposed. New exposures started to decrease around 1990, but about 2000 workers were still exposed each year until 2006.
  • In 2011, 263 new workers were reported, compared with 1447 in 1986.
  • Among Ontario workers, the proportion exposed was 29.7 per 100,000 in 1986. It reached 70 per 100,000 in 1989, then fell to 20.5 per 100,000 in 2005 and 9.9 per 100,000 in 2011.
  • Over the whole period 1986 to 2012, the age-standardized incidence of exposure (per 100,000 population) ranged from 4.7 per 100,000 in Leeds, Grenville, and Lanark District Health Unit to 2954.4 per 100,000 in Lambton Health Unit.
  • From 1986 to 2011, an average of 144 per 100,000 workers in the construction labor force (range 46 to 230) were reported each year. This was almost 10 times higher than in other industries.
  • Although the registry was built for construction, entries came from other sectors. The highest of these rates were in manufacturing and educational services.
  • There were signs of underreporting: only 12 of 36 asbestos removal companies identified in Ontario were in the registry, and only 11 organizations came from the eastern region.
  • Peaks in 1989 reflected reporting by Boards of Education. Of 3306 such entries, 1556 were recorded in 1989, making up 76.6% of the hours and 22.4% of all entries for that year.
  • Most registered workers were men (96%). Women accumulated more hours: half of exposed women had more than 346 hours, compared with 86 hours among men.
  • In the ecological comparison, the highest mesothelioma rates were in areas with the highest exposure rates, such as Lambton County and Hamilton. However, some health units (Northwestern and some eastern units) had high mesothelioma rates but few reported exposed workers.
  • The exploratory ecological analysis could not find a definite link between exposure and mesothelioma.
• The authors' conclusion: The authors concluded that the registry is a useful source of information on asbestos exposure in Ontario but poses challenges for interpretation. In their view, it cannot be used for policy-level decision-making until data quality, representativeness, analysis and dissemination are improved.
• Limitations the authors state:
  • The data were not representative of all potentially exposed workers, which may have biased the prevalence estimates.
  • The ecological analysis could not establish a definite link between exposure and mesothelioma. No individual-level analysis was possible.
  • The place of exposure recorded for individual workers is not fully accurate.
  • Because of the roughly 30-year latency, a strong association with cancer rates reported before 2012 could not be expected.
  • The authors lacked adequate information on workers' occupations.
  • Enforcement of reporting is not systematic, and no information is collected on use of personal protective equipment.
  • The 2011 exposure figure is likely an underestimate.

Topics

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

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