For example, almost everything I deal with...and it's not just the chemical cocktails, on top of that you put things like climate change and stuff. I'm quite surprised. You would think that, of several stressors, some would be additive and some would be antagonistic, if you like. I deal with climate change. Virtually every stressor I deal with seems to be worse in a warmer climate in Canada. It's quite remarkable actually, but that's now putting on another whole other type of stress. For example, you could be working where there are industrial emissions and you have, for example, PAHs, polycyclic aromatic hydrocarbons, being released, which is a carcinogen and so on and so forth. Often those same industries are releasing mercury, for example, in a cocktail of other types of metals. We come up with these analyses on what should be the limit for the PAHs, but we're doing it in isolation from all the other things that are also being released.
Very often some of our assessments are based on overly optimistic scenarios. Very often it's from laboratories where they do ecotoxicological studies, and very often in the real world out there, the situation is far worse and there are other stresses that we haven't even thought of. If you want to quote some people, we have the known knowns, the known unknowns, and the unknown unknowns, and that is quite apparent also in environmental issues. We have some known unknowns, and we have a whole lot of unknown unknowns.
I tend to be an optimist in most things. Although people have called me just overly pessimistic about environmental issues, if I look back on my career of 30 years, I have been overly optimistic on things. Things are generally worse than we think they are in the environment, and we have to be prepared for surprises. Nature is slow to forget our mistakes, and very often if we pass a certain threshold, it's very hard to go backwards.