Mr. Speaker, of course there is scientific evidence. For example, we know very well that there are some countries that have banned specific products on the basis of certain studies and analyses whereas others accept them on the basis of other studies. We find ourselves in a system where the assessment of certain products many not necessarily be identical. It is often a function of peoples' concern for health. “When in doubt, don't” is a an often used saying.
However, some organizations have clearly stated that there is a risk to health and that it increases with the proximity of the product to the individual. In fact, you could spend a whole day beside a sealed container of 2,4-D with no problem at all. The application of 2,4-D on fields by farmers who respect the recommended standards, where people are not nearby, is altogether different than its cosmetic use on lawns, parks and gardens, where people use the product and remain in the parks and gardens.
Therefore, in this matter, the precautionary principle does apply because, I will reiterate, when in doubt, don't. Nevertheless, other scientists also say that there is a danger to health.