Peace -
I'm not sure how smoking got in this thread, but studies by scientists working for big tobacco usually came to the same obvious conclusions as those of the independents. The studies were suppressed by those who paid for them: executives, not scientists.

Even in the fifties and sixties one fact was clear: smoking was a major cause of lung cancer. There was no actual disagreement about this, unless you consider outright lying a disagreement.

Those who claimed that smoking was safe were aware of the falsehood of their claim. They were not disagreeing, they were lying. It's a different matter.