Essentially, our risk-based approach takes a look at the hazards of a certain substance. Is it a carcinogen, a genotoxin? Is there lethality or impacts to, say, fish or other forms of ecological organisms of interest, or trees, or something like that? So we take a look at that and we characterize what the hazards of a certain substance are. We then take a look at the exposure side of it. The first question we will often ask is, is the chemical even in commerce in Canada? In some cases the answer is no, it's not in commerce, in which case it would be subject to the new substance notification regulations. If it is on the DSL, though, just not in commerce, it means that there is potentially no exposure to Canadians at this point in time, but it can come into commerce.
What we do then from an exposure side is take a look at what the sources of release are, assuming it is in commerce in the country, how ecological organisms as well as humans could be exposed to the chemical, and what the exposure levels or the doses are in terms of people being exposed to the substance. From there, we will draw upon a margin of exposure from the human health side and say, are we safe or are we not? From the ecological side we look at a risk quotient, but ultimately we compare exposure concentrations to concentrations that are known to cause effects. When we talk about concentrations known to cause effects, we also build in there application factors to get it down to a level that would probably be safe, to a level that we feel would provide a certain buffer. We call them safety factors.