I understand experiments. But the fact remains that often effects are not linear and that was an extreme dive and that was a very heavy dose. Smoking is a risk factor for cancer. But smelling a bit of smoke around a camp fire is a common risk that many take with little apparent harm. Drinking a glass of water is good. Drinking a couple of gallons has killed a number of people. Seeing an effect under extreme conditions may raise a question but it does not establish an actual risk.