A minute of secondhand marijuana smoke may damage blood vessels

July 27, 2016, American Heart Association
A dried flower bud of the Cannabis plant. Credit: Public Domain

Rats' blood vessels took at least three times longer to recover function after only a minute of breathing secondhand marijuana smoke, compared to recovery after a minute of breathing secondhand tobacco smoke, according to new research in Journal of the American Heart Association, the Open Access Journal of the American Heart Association/American Stroke Association.

When rats inhaled secondhand marijuana smoke for one minute, their arteries carried blood less efficiently for at least 90 minutes, whereas similar exposure to secondhand caused blood vessel impairment that recovered within 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.

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

"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 responsible for the impaired , not chemicals like nicotine and tetrahydrocannabinol (THC), the psychoactive ingredient in marijuana, nor rolling paper.

"There is widespread belief that, unlike tobacco smoke, marijuana smoke is benign," Springer 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."

Springer also noted that 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 exposure.

The inhalation of smoke should be avoided, regardless of whether it comes from tobacco, marijuana, or other sources. Inhaling smoke is bad for you—period, researchers said.

Explore further: Secondhand marijuana smoke may damage blood vessels as much as tobacco smoke

Related Stories

Secondhand marijuana smoke may damage blood vessels as much as tobacco smoke

November 16, 2014
Breathing secondhand marijuana smoke could damage your heart and blood vessels as much as secondhand cigarette smoke, according to preliminary research presented at the American Heart Association's Scientific Sessions 2014.

One in six children hospitalized for lung inflammation positive for marijuana exposure

April 30, 2016
A new study to be presented at the Pediatric Academic Societies 2016 Meeting found that one in six infants and toddlers admitted to a Colorado hospital with coughing, wheezing and other symptoms of bronchiolitis tested positive ...

Apartment dwellers more likely to smoke: CDC

July 13, 2016
(HealthDay)—Apartment residents are more likely to smoke and less likely to have smoke-free rules than people living in single-family homes, U.S. health officials report.

Secondhand smoke hits almost half of teens who don't smoke

January 11, 2016
Even though fewer U.S. teens are smoking, secondhand smoke remains a big problem for them, a government study found.

Occasional marijuana use doesn't harm lungs, study finds

January 12, 2012
Smoking marijuana on an occasional basis does not appear to significantly damage the lungs, according to a new study.

Recommended for you

Drinking alcohol makes your heart race

March 18, 2018
The more alcohol you drink, the higher your heart rate gets, according to research presented today at EHRA 2018 Congress, organized by the European Society of Cardiology.

Study of nearly 300,000 people challenges the 'obesity paradox'

March 15, 2018
The idea that it might be possible to be overweight or obese but not at increased risk of heart disease, otherwise known as the "obesity paradox", has been challenged by a study of nearly 300,000 people published in in the ...

Mending broken hearts with cardiomyocyte molds

March 13, 2018
2.5 billion. That's approximately the number of times the human heart beats in 70 years. And sometimes during the course of its unrelenting contractions and relaxations, the heart muscle can no longer bear the strain.

Common infections a bigger heart disease and stroke risk than obesity

March 13, 2018
A major study into the impact of common infections leading to hospitalisation has found they may substantially increase the risk of heart attacks, strokes and in the longer term, death.

Aspirin prevents venous thromboembolism following major orthopedic surgeries, study finds

March 13, 2018
A multicentre, double-blind, randomized, controlled clinical trial of patients who underwent total hip or knee replacement surgery showed that aspirin was as effective as rivaroxaban, the standard anti-coagulation medication, ...

Barbershop-based healthcare study successfully lowers high blood pressure in African-American men

March 12, 2018
African-American men successfully lowered their high blood pressure to healthy levels when aided by a pharmacist and their local barber, according to a new study from the Smidt Heart Institute.


Adjust slider to filter visible comments by rank

Display comments: newest first

5 / 5 (1) Jul 27, 2016
Wernicke's encephalopathy and WKS is most commonly seen in people who are alcoholic, and only 20% of cases are identified before death. This failure in diagnosis of WE and thus treatment of the disease leads to death in approximately 20% of cases, while 75% are left with permanent brain damage associated with WKS.[2] Of those affected, 25% require long-term institutionalization in order to receive effective care or "Wet Brain" NOW! thats really something to fret over ,or having a raging drunk cross your path and for some the unexpected blackout or becoming derelict....much like a "Wino". Second hand reefer smoke my A$$. Just get a VAPE!.It's only damn POT! not like it's DOPE!
not rated yet Jul 27, 2016
this medxp site is getting really old with all their reefer madness bullspit. total, unmitigated bullspit. there are MILLIONS of users who have smoked for 50+ years and there are ZERO reported cases of this happening to humans ....... EVER. shame on whatever editor decided this was good to go. idiots. pull your collective heads out of your arses.
5 / 5 (1) Jul 27, 2016
The real story is here:

>>>"Researchers also found the mere burning of the plant material appears responsible for the impaired blood vessels, not chemicals like nicotine and tetrahydrocannabinol (THC), the psychoactive ingredient in marijuana, nor rolling paper." ----------

Thank goodness we consumers figured this out more than a decade ago. - Use a vaporizer! - No smoke, no harm, at all. ---------

For clarity, it should be emphasized that tobacco smoke is MUCH more harmful than marijuana smoke outside the narrow confines of this study. Tobacco smoke KILLS more people than any other recreational drug, causing a hundred thousand deaths, primarily from lung cancer, each year, in the U.S. alone! - There are no recorded deaths from smoking marijuana in all of recorded history.
not rated yet Jul 27, 2016
Another useless article about an equally useless study. The headline says "secondhand marijuana smoke may damage blood vessels" but no where does the study say or imply that it does. It just says they operated less efficiently for a short period of time. And the article does not indicate how much less efficiently. 10%? 15%? 0.0004%? This was an article designed to generate clicks, not provide information. And about a study that was designed to try and get publicity, not research legit health concerns.
not rated yet Jul 27, 2016
The country's leading researcher of marijuana and lung disease, UCLA's Dr. Donald Tashkin, conducted investigations over 30 years, initially believing there must be a causal relationship. But he finally concluded that smoking marijuana does NOT cause cancer or ANY other serious disease. -----

Tashkin said: "We hypothesized that there would be a positive association between marijuana use and lung cancer, and that the association would be more positive with heavier use. What we found instead was no association at all, and even some suggestion of a protective effect."
5 / 5 (1) Jul 27, 2016
reefer madness will damage you brain !
not rated yet Jul 28, 2016
But reefer itself is good for it.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.