[lolinder]

I think you need to flesh that standard out a bit. Maybe something more like this:

> If the material has been in continual use since before the industrial age and we have yet to find any evidence of harm, it is far more likely to be safe than newer materials with which we have fewer centuries of experience.

Our ancestors used all kinds of things that were terrible for them and it doesn't require overintellectualizing to find exceptions, they're everywhere. But this late in the development of medicine it is fairly reasonable to suggest that if there's a long-standing tradition of using a material and we have yet to find that it causes harm, it is more likely to be safe than something new.