Occupational exposure limits for carcinogens in Ontario workplaces: Opportunities to prevent and control exposure

Status: dormant


The goal of this project is to identify opportunities for Ontario to improve its occupational exposure limits for carcinogens.


Over 200 substances or agents are known or likely to cause cancer in humans according to the International Agency for Research on Cancer. Many of these carcinogens are found in workplaces, such as industrial chemicals, pesticides, and radiation. Estimates of the number of cancers that are due to workplace exposures vary widely, but all of these are preventable.

Occupational exposure limits are legal or recommended maximum allowable concentrations of a hazardous substance in a workplace. These values are usually set by national authorities or other institutions. To help prevent cancer and protect health, it is important that limits for carcinogens are rigorous, up-to-date, and reflect the best possible standards for workers.



In order to report on occupational carcinogens that are relevant to Ontario workers, we began with the list of nearly 100 exposures identified as research priorities by OCRC’s stakeholder community in 2009. We then obtained the list of carcinogens profiled on the CAREX Canada website. We found the occupational exposure limits for each of these 79 carcinogens in Ontario and compared them to values across Canada and in six other jurisdictions. Estimates of the number of workers exposed were drawn from CAREX Canada. We focused our discussion on the carcinogens that had limits that greatly varied across jurisdictions and had limits in Ontario that exceeded the other jurisdictions. Based on this evidence, we made specific recommendations for carcinogens that can have more rigorous limits in Ontario.


Cancer and other health effects can occur from lower levels of exposure. This project highlights that Ontario should monitor the standards set by other jurisdictions and take a lead in establishing rigorous values. Key recommendations generated from this analysis support continued research efforts and policy-making to decrease occupational exposure limits in Ontario.


The Ontario Ministry of Labour’s annual OEL update process includes a public consultation in which stakeholders are invited to submit comments on the proposed changes. The OCRC has prepared submissions for the 2012, 2013, and 2014 reviews.


OCRC response to 2018 proposed OEL changes

2014 OCRC OEL Recommendations
2013 OCRC OEL Recommendations
2012 OCRC OEL Recommendations
Poster based on the 2012 report


Paul Demers (Occupational Cancer Research Centre)
Manisha Pahwa (Occupational Cancer Research Centre)
Calvin Ge (CAREX Canada)