[umanwizard]

Lung cancer is caused by smoking 85-90% of the time. Probably more if you add in secondhand smoke. I think it already meets any sort of "preponderance of evidence" sort of bar to just assume anyone with lung cancer got it from smoking.

[wallyhs]

Suppose that I live in an apartment with a wood stove, second-hand smoke from a room mate, and radon. If I get lung cancer, which one is to blame? How do you know?

[ghurtado]

Citation / reference needed.

[umanwizard]

I googled it and the same stat on a couple different reputable sites, like that of the American Lung Association and the American Cancer Society.