I think that when risk assessments are done on substances sometimes...triclosan is a good example, because it's one I know well. It was declared toxic to the environment in a draft decision, but it wasn't declared toxic to human health. We have seen a great deal of evidence that it mimics the human thyroid hormone and affects other organs of the body as well.
The Canadian Medical Association has been calling for a ban on it since 2009 because of concerns that it contributes to antibiotic-resistant bacteria. There is a great deal of evidence that it's a human health hazard. I won't go further down that path at the moment, but if we were to apply the precautionary principle in its holistic sense, I think we would see that being declared toxic to human health as well, in light of mounting evidence.
Another shout-out is IARC, the International Agency for Research on Cancer. A cancer researcher recently said that a substance has never gone down when it has its IARC designation of 2B or above, meaning that there's more and more evidence that it causes cancer. There aren't examples of substances that then get reviewed and taken off that list, that we found don't cause cancer, even though we were moving up that chain. Things don't go in reverse that way.
That's evidence that the precautionary principle when applied in risk assessment is quite up to international standards to be very cautious.