Richard Beasley, MBChB, DM, FRACP, DSc, Director of the Medical Research Institute of New Zealand, in a Jan. 29, 2008 interview with Reuters explaining the results of his Feb. 2008 study "Cannabis Use and Risk of Lung Cancer: a Case–control Study" in the European Respiratory Journal:

“Cannabis smokers end up with five times more carbon monoxide in their bloodstream (than tobacco smokers)…

In the near future we may see an ‘epidemic’ of lung cancers connected with this new carcinogen. And the future risk probably applies to many other countries, where increasing use of cannabis among young adults and adolescents is becoming a major public health problem.”

Jan. 29, 2008