Comment by madaxe_again

You should see how the second hand smoke studies upon which all other second hand smoke studies were based were done - very similar methodology - cotton swabs were saturated with combustion residues from hundreds of cigarettes, making them into tarry masses, which were then applied to 100% of the bodies of infant rats, every day for several weeks - and they were then observed for developmental abnormalities. The discussion then explicitly states that this should not be taken as a human analogue, as the rats were seen to lick the residue off their bodies, thus consuming all of it, and that further research would be needed.

Further research was of course done - on rats - with much the same methodology.

Medicine is really prone to falling for this sort of thing - and it’s honestly no great shock, recalling the calibre of people at school who went on to become doctors. I studied physics, for Christ’s sake, and knew more about metabolic pathways than third year med students who I would help cram.