> Impossible standard. You cannot prove a negative
It's also a deep incumbency advantage. Of course the guys selling the existing stuff are going to dispute the safety of a competitor.
And when a chemical goes off patent protection and you have a new patented chemical ready to go, it's advantageous to suddenly dis the now public domain entity.
And when a chemical goes off patent protection and you have a new patented chemical ready to go, it's advantageous to suddenly dis the now public domain entity.