Pot Smoking Not Linked to Lung Cancer Web MD
Pot is non-carcinogenic. Comparing to tobacco is silly. Cigarettes in their current form are very carcinogenic and deadly.
Gramps, pot in itself is not non-carcinogenic as you suggest, and the piece you referenced even states as much.
The issue is that there are as many carcinogens existing in pot smoke as there is in tobacco smoke, and by all accounts it should contribute to an increase of lung and other cancers. However the study has reportedly found that increased incidents of cancer did not correlate with heavy pot smoking.
The reason apparently remains up for study and investigation, but some have suggested it is THC that is responsible for the disparity between the cig and the doob numbers, and perhaps it counteracts the effects of the known carcinogens. The antithesis of nicotine, which apparently enhances the carcinogenic effect of the chemicals.
But the mentioned study could also bring up other questions...such as could it be that they really don't understand what is happening with tobacco either? Perhaps it is one of the ingredients that the cigarette makers use that interacts with the chemicals that is the big problem and not the plant matter itself?