Latest study suggests that inhaling secondhand marijuana smoke is also harmful and can damage blood vessels and the heart.

Many people know the fact that secondhand cigarette smoke is bad, but many people are not aware that secondhand smoke from marijuana is also equally bad for a non-smoker.

The study was conducted by the researchers at the University of California, San Francisco (UCSF), which suggests that smoke from tobacco and marijuana are physically and chemically alike, and inhaling marijuana smoke is as harmful and dangerous as inhaling smoke from tobacco such as from cigarettes for non-smokers.

Matthew Springer, an associate professor of Medicine at UCSF's Cardiology Division and a cardiovascular researcher, who is also the senior author of the study, reveals that the team conducted an experiment on lab mice and found adverse medical effects on the rodents.

The study involved using a modified version of a cigarette smoking device to expose lab mice to the smoke of marijuana. The scientists monitored the main leg artery function of the mice using a high-resolution ultrasound device.

Springer revealed that the function of blood vessels in lab mice reduced to 70 percent just after being exposed to marijuana smoke for between 10 and 40 minutes. The researchers also found that smoke from marijuana without tetrahydrocannabinol (THC), which is a compound that generates intoxication, also impaired the function of blood vessels in the mice.

Citing previous studies, the scientists reveal that the function of blood vessels went back to normal within just 30 minutes of exposure from tobacco smoke. However, the new marijuana study reveals that the function of blood vessels did not go back to normal even when it was measured 40 minutes following the exposure.

Scientists suggest that reduced function of the blood vessels may also elevate the chances of getting atherosclerosis and may lead to a heart attack. Atherosclerosis is hardening of the arteries that causes build-up of plaque in the arteries resulting in their narrowing and eventually restricting blood flow.

The scientists confirmed that the reduced function of the blood vessels from marijuana without THC indicates that this compound is not accountable for the adverse effect. Similarly, the study also approves that nicotine is not needed for smoke to obstruct the function of blood vessels.

The study is significant as marijuana use is getting increasingly legalized in many states of the U.S., which poses a high level of concern for public.

"If you're hanging out in a room where people are smoking a lot of marijuana, you may be harming your blood vessels," says Springer. "There's no reason to think marijuana smoke is better than tobacco smoke. Avoid them both."

The preliminary research was presented at the American Heart Association's Scientific Sessions 2014. 

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