Quote:
Originally Posted by JonoBN41
But all these studies and meta studies aside, remember that cigarette smoking was very early identified as causing lung cancer and heart disease for the very reason that smokers got it, and non-smokers didn't. If in fact second-hand smoke had had a similar effect on everyone, we would still be trying to figure out what was causing it.
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Not really - the connection between smoking and lung cancer came in two separate but related prongs, one dealing with actual laboratory studies using live tissue (see: "tar-painting" studies on mice) and one dealing with epidemiological evidence (such as the NCI's Monograph series, found
here.
Now, you're trying to say that epidemiological evidence should have been clouded or subverted completely if second-hand smoke also causes cancer. However, this is likely false, if you consider that active smoking is considerably more dangerous than passive (or second-hand) smoking - this increase in scale would likely be sufficient to find the smoking/cancer link on its own. This is not a sufficient condition to claim that passive smoking is not dangerous - after all, there are other kinds of lung cancer as well. Just because we can separate smoking from, say, asbestos exposure, this doesn't mean that asbestos no longer is a 'cause' of lung cancers (mesothelioma, to be precise, but the point remains).
It's not enough to get cute with a statement like "If second-hand smoke had an effect similar to smoking . . ." because that's not the issue. In fact, if passive smoking is even 1/100th as dangerous as active smoking, it becomes a public health hazard. The science isn't perfect, but to deny the effects of inhaling smoke for second-hand users is as laughable as denying the effects of the same action on active smokers.