I have a couple of comments on this.
I think it's very important to understand that Environment Canada and Health Canada have actually applied an extremely high standard of proof in their assessment of the toxicity of substances. Indeed, in order for something to be found toxic under CEPA, it would almost certainly have to be causing actual harm to the environment or human health rather than merely presenting a risk. The standard of proof they've employed is very high.
In fact, strong arguments have been made that the current process for assessing substances added to the list is excessively cautious, and things that should have been added to the list haven't been. In that context, I think the label of toxic is entirely appropriate; it sends a signal to the public that this is something to exercise caution around.
It's also, in a sense, relatively mild. I think the degree to which the public actually identifies this is still an open question. Other jurisdictions have in fact been much more aggressive. California, for example, through their proposition 65 actually requires the labelling of all consumer products that contain a number of listed substances, which runs into the hundreds. You actually see consumer products with labels on them--this is a carcinogen, or this is a developmental toxin.
Compared to that, I would say the approach under CEPA is extremely conservative.