Back in the day, about 20-30 years ago, rats were force fed up to 2000 times or more of the normal amount of artificial sweeteners, diet sodas, even pesticides, to study how long term use or exposure of certain chemicals would effect humans. It seemed like every week, something was "found to cause cancer in laboratory rats."
I mentioned to my brother these "scientists" would keep "testing" until they found out breast milk caused cancer.
Damned if they didn't!