The Ontario Mining Exposure Database


In order to better understand the potential risks to workers in the mining industry and to inform prevention activities, the OCRC created a database of exposure measurements collected in mines in Ontario. The objective was to create a database that will serve as a valuable tool for exposure surveillance and prevention in the Ontario mining industry.

Now completed, the database is being used to:
• Examine trends in mining exposures over time
• Evaluate the effect of historical interventions, such as regulation or technological change, on exposure levels
• Examine differences in exposure related to mine type and location
• Explore the construction of job-exposure matrices for common mining exposures

On this page:


In 2011, there were 38 mines operating in Ontario with over 18,000 people employed in mining operations. Workers in the mining industry may be exposed to carcinogens, including radon, crystalline silica, diesel engine exhaust, arsenic, nickel, and chromium. Many of these exposures can also negatively impact the respiratory health of workers. Despite this, there was previously no centralized or accessible database of exposure measurements from mines in Ontario, and therefore no easy way to track exposures across the mining sector. Records of exposure measurements are often stored in paper form, and may be subject to damage or loss. Digitalizing these records in an electronic database (Ontario mining exposure database) provides long-term data security and allows for the identification of exposure trends over time and across Ontario.


Data from the Ministry of Labour, research organizations, health and safety associations, and mining companies has been identified across Ontario. The OCRC entered into a legally binding data sharing agreement with Ontario Ministry of Labour and other organizations, including Workplace Safety North (WSN) and Laurentian University, to locate exposure data and enter it into an electronic database.  Hard copies of the exposure data are transported to the OCRC office for thorough review, entry into the database, and subsequent analysis. Descriptive statistics and exposure trends over time have been explored. Several models using various determinants of exposure have been investigated.

  • In the underground group of miners, a 6% annual decrease over time was observed. In this group, the commodity group with the highest average respirable crystalline silica (RCS) level was zinc mines and the lowest was iron mines. In the surface group, an 8% decreased over time was observed and the commodity group with the highest average RCS level was gold mines and while the lowest was observed in zinc mines. In both groups company-collected data had lower estimated RCS compared to regulator-collected data.
  • More results are available in the manuscript: Estimating historical exposure to respirable crystalline silica in the mining industry in Ontario, Canada using a newly developed exposure database (Accepted April 1, 2021 by the journal Annals for Exposures and Health).

Analyses using the database will increase our understanding of exposures in the mining industry and help target prevention efforts where they will have the greatest impact on workers’ health. Additional future applications of the database include designing interventions to minimize exposures that will have the biggest impact on workers’ health and improving research methods for assessing exposures as part of ongoing cohort studies of mining-related disease.

Progress (updated April 2021)

Data analysis is mostly completed and a manuscript was prepared for this the project. As a separate project, we are currently exploring the feasibility of using the Ontario mining exposure database to create a simpler job exposure matrix (JEM) for silica. The JEM can be used to assign exposures to mining cohorts available at the OCRC and estimate cumulative exposures.

  • In the 2012 Bridging the Gap competition, the Occupational Cancer Research Centre (OCRC) was awarded funding to assess the feasibility of creating the database.
  • Funding for completion of the full database was received from the Ontario Ministry of Labour: Demers PA, Arrandale VH, Lightfoot NE, Genesove LJ. Creation of the Ontario Mining Exposure Database. 2014-2015.
  • Funding for analysis of the database was also awarded by the Ontario Ministry of Labour:
    Demers PA, Arrandale VH, Lightfoot NE. Occupational Exposure Surveillance in the Ontario Mining Industry. 2015-2017.
Scientific Article
  • Estimating Historical Exposure to Respirable Crystalline Silica in the Mining Industry in Ontario, Canada Using a Newly Developed Exposure Database

Research Team
Paul Demers
Nancy E Lightfoot
Laurentian University
Leon J Genesove
Ontario Ministry of Labour
Victoria H Arrandale
OCRC and University of Toronto
Linh Nguyen
Colin Berriault
Kate Jardine
Nicola Blagrove-Hall