[Foober223]

I guess if you can observe the damaging mechanic at the cellular level that is proof of causation. Rather than just statistical correlation.

All tests that just look for end results without understanding the mechanism would be showing statistical correlation. But correlation is good info. In the real world, you are going to be well off taking statistical correlation to heart. The Romans knew asbestos was deadly long before there was any ability to observe mechanics at the cellular level. All they had to go on was that people covered in asbestos died horrific deaths.