On January 15, 2011, the Ministers of Environment and Health published notice of their intention to add forty petroleum and refinery gases, which are currently specified on the Domestic Substances List, to the List of Toxic Substances (Schedule 1 of CEPA, 1999). These gases are produced during petroleum refining, upgrading or natural gas processing, and vary in composition depending upon the source of crude oil, bitumen or natural gas, and processing. They are considered “site restricted” substances, in that they are typically not transported offsite, but are instead consumed as fuels on-site, or used as feedstocks within a facility.

Environment Canada noted that some releases of petroleum and refinery gases into the atmosphere may occur, contributing to ambient background levels of 1,3-butadiene. These gases are considered to be persistent in the atmosphere, but not bioaccumulative or inherently toxic to non-human organisms. Carcinogenicity was considered to be a critical effect for human health risk characterization, in particular in relation to 1,3-butadiene.

The Screening Assessment and Risk Management scope document for these substances are available at www.chemicalsubstances.gc.ca.