Marijuana Secondhand Smoke Isn’t as Bad as Tobacco Smoke

Few serious people would bother to argue tobacco is healthier than cannabis. Even for a contrarian, it’s a doomed exercise. Surely few people could honestly make this argument. Certainly they couldn’t declare that secondhand exposure to cannabis smoke is worse than breathing secondhand tobacco smoke.

Yet such a line is being pushed in our discourse, right now — and not for the first time.

“Secondhand smoke more dangerous from marijuana than cigarettes: Study,” reads a headline published in the Washington Times on March 20. Other news outlets were more circumspect. “Are there risks from secondhand marijuana smoke? Early science says yes,” the Philadelphia Inquirer posited on March 26, but the takeaway is the same.

Such source material has been used to ring a “maybe marijuana is as bad as cigarettes, or worse!” bell for much of the past decade. You could work very hard and look very deep and not find a better example of a false equivalency, based on a faulty premise.

Incredibly, the institution responsible for pushing a line that’s leading news outlets and their readers to put both cannabis and tobacco in the same deadly bucket happens to be based in San Francisco, the historic home of medical marijuana and the legalization movement.

Matt Springer, a researcher from the University of California, San Francisco — one of the nation’s leading institutions for data about smoking and lung health — has been investigating the impact of cannabis smoking on lung health for much of the past decade. He opened this line of inquiry after attending a Paul McCartney concert at AT&T Park in 2010, where he smelled lots and lots of marijuana being burned.

Springer and the university published findings suggesting cannabis smoke is just as bad — or even worse! — than tobacco smoke in 2014 and 2016, as well as earlier this year, setting off the same round of alarmist headlines.

Each time, the source material came from the same body of work. Springer and his researcher team exposed lab rats, whose cardiovascular systems aren’t too dissimilar from ours, to second-hand marijuana smoke.

They found the rats’ blood vessels became constricted and took longer to return to normal than when they were exposed to tobacco smoke. The data changed somewhat — in 2014, the researchers found that rats’ blood vessels’ ability to dilate and increase blood flow was 70 percent reduced, a figure they changed to 50 percent in 2016.

Cannabis users likely have experienced the same phenomenon as Springer’s lab rats. Cannabis use leads to a brief temporary spike in blood pressure as the body’s blood vessels constrict. This can lead to a heightened heart rate, and light-headedness or dizziness if a person stands up quickly. It can also lead to the feeling that “I’m freaking out, man” and the accompanying lifetime of declaring “weed freaks me out.”

The thing is (and this is important!) tobacco use involves a host of other deleterious health effects that have not been linked to cannabis use. You might have heard of them. Lung cancer, COPD, heart disease, reduced lung function. To date, the only longitudinal study examining marijuana use found no link between cannabis smoking and these horrible diseases. In fact, initial results suggested they have a mild protective effect. The findings were “against our expectations,” said Donald Tashkin, the University of California, Los Angeles researcher who led the study. (Also notable: Tashkin’s study should be given more weight than other results from Europe and the United Kingdom, where most cannabis users consume the drug mixed with tobacco, a practice less widespread in the U.S.)

This latest recycling of Springer’s research, willfully manipulated by the Times and other outlets to make it appear that cannabis is in the same league as tobacco, is the fault of Kaiser Health News, which published a story whose message was essentially, “cannabis smoke exposure is under-studied.” And yes, this is true. What’s not by any metric true is the theory that the two drugs pose similar risks to human health.

Tobacco smoking is the world’s leading cause of preventable death. More than 480,000 Americans die every year because of smoking cigarettes — including 41,000 people whose deaths are attributable to secondhand smoke exposure. Notably, and famously, cannabis has killed no one, despite many well-funded efforts to prove otherwise.

But the thing is, tobacco users currently enjoy more freedom and rights than cannabis users. Smoking cannabis in public, anywhere at all, is punishable by a citation in California, Colorado, and most everywhere else the drug is legal. A cigarette user in the exact same spot, the patio of a bar, for example, can puff away with impunity. That’s intellectually dishonest by any metric.

TELL US, do think secondhand smoke from tobacco is worse than from cannabis?