Marijuana smoke puts the same kind of strain on blood vessels that tobacco smoke does, research has revealed.
Cannabis is now legal to use medicinally or recreationally in 29 states and two extracts from the plant have even been approved by the FDA to treat chemotherapy-related nausea.
Its medicinal uses have given the drug a positive reputation in recent years, but smoke is still smoke, an expert from the University of California, San Francisco warns.
Smoke from a joint – marijuana rolled in paper – has the same weakening short-term effects on blood vessels that cigarette smoke does, but last three times as long, research has revealed.
Secondhand marijuana smoke impairs blood vessel functions in the same was as tobacco smoke, but the effects last three times as long, research shows
Though it is still classified as a schedule I drug by the US Drug Enforcement Agency, marijuana has come a long way in the public eye since the days when it was called ‘the devil’s lettuce.’
Much of the fear and stigma that long surrounded (and still does, in some places) marijuana has been tied to the psychoactive effects of its active component, THC.
Research has yet to demonstrate clear benefits or harms of THC on the brain, but has, on the other hand, supplied evidence that the non-psychoactive cannabinoids in marijuana can ease anxiety, pain and nausea.
But as the drug itself becomes more widely accepted, a widespread presumption that using it – in any form – is ‘safe’ has followed.
Yet, in states where it is legal, most people are still rolling the buds from marijuana plants into joints, lighting up, and smoking them, at home or even in public, where others may be exposed to secondhand smoke.
In California, where medicinal marijuana has been legal since 1996, more than half of all consumers use it by smoking the dried buds in papers, bongs or pipes.
Doing so exposes them to some of the same negative health effects that smoking tobacco cigarettes would, according to recent research.
Dr Matthew Springer and his team at the University of California, San Francisco, exposed lab rats to secondhand-levels of both tobacco and marijuana smoke.
After one minute of exposure to either kind of smoke, the rats blood vessel function was impaired by about 50 percent.
This effect is short-term, but experts suspect that repeated exposures lead to long-lasting damage and the poor cardiovascular health seen in cigarette smokers.
However, the rats exposed to cigarette smoke recovered their blood vessel function within 30 minutes, while those that were around secondhand marijuana smoke were still suffering the effects 90 minutes later.
It’s unclear why the damage of one would last longer than the other, but ‘they’re both the result of burning dry plants,’ says Dr Springer.
We’ve proven that there is a harmful effect of tobacco that marijuana has too. That means you can no longer assume that marijuana is harmless
Dr Matthew Springer, UCSF cardiologist
‘When you burn dry plants, you get thousands of chemicals that are very, very similar, whether it is smoke from wood, tobacco, or marijuana, and many of them are toxic,’ he explains.
Many people have the impression that nicotine is the harmful aspect of of cigarettes and that marijuana smoke is not dangerous because it does not contain nicotine, Dr Springer says.
But that is not the case. ‘Weed smoke has cannabis, tobacco has nicotine, but other than those we found all the same chemicals’ in the smoke, he says.
‘Much of the harm is coming from these other compounds, and both kinds of smoke consist of fine particles getting inhaled into the lungs.
‘These fine particles are similar to air pollution and are thought to have cardiovascular effects all on their own,’ says Dr Springer.
These effects will be felt either from smoking yourself or from being exposed to secondhand smoke.
He says that the misconception that the effects of smoking marijuana as opposed to tobacco are largely reputational.
‘A lot of people will say that marijuana is natural and they view tobacco as a concoction of chemicals from tobacco companies and marijuana as a pure plant,’ he explains.
There is some truth to that, as there are additives in cigarettes. But perhaps more importantly, while there have been sweeping public health campaigns against cigarettes, marijuana has been given a ‘glow’ because of its medicinal properties.
There has been far less research on the health risks of marijuana smoke than there has on tobacco smoke, and ‘people mistake the absence of evidence of harm for the evidence of absence of harm,’ Dr Springer says.
But his research, he hopes, will debunk that assumption.
‘The take-home lesson is that, even though we haven’t proven that this has harmful effects in humans, we’ve proven that there is a harmful effect of tobacco that marijuana has too.
‘That means you can no longer assume that marijuana is harmless,’ Dr Springer says.