I'll try. It's a difficult subject.
To protect human health, countries around the world have an absolute standard below which they will not go. We do as well. Protecting human health, we say, and the environment, are our primary mandates. But the act is clear: we have to consider the competitiveness of the agriculture sector and we have to consider providing tools--pesticides--to users in Canada.
For human health, when you think of consuming residues on foods, there is, based on the toxicity of a pesticide, an absolute amount that we won't let you consume above. Now typically, in any country, a number of pesticides are contributing to that amount. The difficulty comes because we don't have the same multiples of pesticides registered in every country.
In Canada, if I say, for chemical A, that we have ten products that have chemical A in them and we're going to make sure you don't consume above this amount, we might set an MRL of ten for each of the ten. In the United States they might have 200 different pesticides that have that active in it. They might have to set a lower MRL to make sure that the total consumption doesn't go above that level. They might have two pesticides and could set a higher MRL to make sure you don't go above that consumption.
The reaction of the human body to a chemical remains the same no matter if you're here, in California, in Cuba, in New Zealand, or in Japan.
With respect to the effects on the environment, that can be quite different. It obviously depends very much on the kind of environment in which you're using a pesticide. For example, we know that sun decomposes or breaks down most pesticides. So if you're in a tropical country with a lot of sunlight, the level of pesticide in the environment is likely to deteriorate faster with time than if you're in Canada, which has a northern climate. You're trying to control both environmental exposure and human health exposure through the use of the pesticides. Because they can be used on many different foods, you have this concern about maximum residue limits and differences all over.
When we look at safety, we look at the toxicity of the pesticide. We look at, in Canada, what foods it's used on and what foods are imported into Canada with potential pesticide residues. We have data on what Canadians consume, and that goes from infants right through to seniors, broken down by subpopulation group and gender. We synthesize all those things when we're setting an MRL.
There is often the ability to protect human health and protect the environment and change an MRL and change use, but sometimes there isn't.