The traditional approach in Canada has been primarily substance by substance, but that has not always been the case. Some of the earliest assessments were of effluent from pulp and paper and effluent from metal mining, for example, which comprised multiple substances. We've alway had that authority.
As I explained in response to an earlier question, we are now moving from a commitment to look at 4,300 individual substances to increasingly looking at combinations of substances or classes of substances using existing authorities.