smoke veins

Secondhand marijuana smoke may damage your blood vessels even more than tobacco smoke.

In a new study, arteries in rats that inhaled secondhand marijuana smoke for one minute carried blood less efficiently for at least 90 minutes. Similar exposure to secondhand tobacco smoke caused blood vessel impairment for 30 minutes.

“While the effect is temporary for both cigarette and marijuana smoke, these temporary problems can turn into long-term problems if exposures occur often enough and may increase the chances of developing hardened and clogged arteries,” said Matthew Springer, Ph.D., study senior author and professor of medicine at the University of California, San Francisco’s Division of Cardiology.

Researchers examined blood vessel function in rats before and after exposure to secondhand marijuana and tobacco smoke similar to real-world levels.

“Arteries of rats and humans are similar in how they respond to secondhand tobacco smoke, so the response of rat arteries to secondhand marijuana smoke is likely to reflect how human arteries might respond,” Springer said.

Researchers also found the mere burning of the plant material appears to cause the impaired blood vessels — not chemicals like nicotine and tetrahydrocannabinol, the psychoactive ingredient in marijuana, nor rolling paper.

The increasing number of states legalizing medicinal and recreational marijuana, along with increasing potential for corporate expansion within the cannabis industry, makes it important to understand the health consequences of secondhand marijuana smoke exposure, Springer said

“There is widespread belief that, unlike tobacco smoke, marijuana smoke is benign,” he said. “We in public health have been telling the public to avoid secondhand tobacco smoke for years. But we don’t tell them to avoid secondhand marijuana smoke, because until now we haven’t had evidence that it can be harmful.”

The study is published in the Journal of the American Heart Association.