Obviously “we” don’t, as there are no definitive links to cancer from cannabis smoke alone.
Granted, McLellan did say, “There are so many more ways to take your cannabis these days,” so she’s not advocating complete cessation, she just prefers other means of delivery. Which is fine, vaping is better than smoking, but unlike tobacco, smoking cannabis is not a form of slow-motion suicide.
But because cannabis smoke contains many of the same carcinogens as tobacco, McLellan is likely concluding that cannabis smoke is just as deadly as tobacco smoke.
This ignores everything we know about cannabis.
Cannabis smoke contains cannabinoids such as THC and CBD which are non-carcinogenic and demonstrate anti-cancer properties.
Whereas nicotine promotes developing cancer cells, cannabinoids mitigate the carcinogenic effects of smoke. Cannabidiol is an anti-inflammatory and responsible for downplaying the “free radicals” that accelerate cancer cells.
More research is needed before McLellan can make such a blanket statement.
A case-control study of 164 oral cancer patients and 526 controls haven’t produced positive results. Researchers at John Hopkins University in Baltimore concluded, “The balance of evidence from this, the largest case-control study addressing marijuana use and cancer to date, does not favor the idea that marijuana as commonly used in the community is a major causal factor for head, neck or lung cancer in young adults.”
A 2004 population-based case-control study of 407 individuals found “no association” between cannabis use and oral cancer. A follow-up study found the same thing.
A 1997 study examining cannabis and cancer in 65,171 men and women aged 15 to 49 found no increased risks of developing tobacco-use related cancers of the lung and upper aerodigestive tract (includes the lips, mouth, tongue, nose, throat, vocal cords, and part of the esophagus and windpipe).
Furthermore, no cases of lung cancer were found in those who used cannabis but not tobacco.
A 1998 report by the British House of Lords Science and Technology Committee also found no evidence for increased lung cancer in cannabis smokers.
An 18-month study by the US National Academy of Science Institute of Medicine also found no conclusive evidence that marijuana causes cancer in humans, including cancers generally related to tobacco use.
Our own 2002 Canadian Senate review found the same thing, that case studies in literature were also “limited by the fact the patients smoked tobacco and drank alcohol.”
In journals such as Alcohol and Lancet Oncology, reviews and a 14 case-control study did not reveal “an increased risk of tobacco related cancers among marijuana smokers.”
A 2005 review found, “a conspicuous lack of evidence on the association between cannabis smoking and lung cancers.”
You’d think the head of Canada’s legalization task force would know this.
But, then again, it is a task farce. They think prohibition will work when applied to minors, that BC Bud is synonymous with violent, organized crime, and that adults need Health Canada‘s strict regulation or else they’ll get sick from contaminated cannabis.
So I guess McLellan’s ignorance shouldn’t come as a surprise.