Impact Of Secondhand Pot Smoke On Heart Health

Chuck Bednar for redOrbit.com – Your Universe Online
Secondhand marijuana smoke could be as damaging to your heart and blood vessels as secondhand cigarette smoke, researchers from the University of California, San Francisco (UCSF) reported at the American Heart Association’s Scientific Sessions 2014 in Chicago on Sunday.
In the preliminary study, the authors reported that blood vessel function in laboratory rats that had been exposed to secondhand marijuana smoke for 30 minutes dropped 70 percent, even when it did not contain tetrahydrocannabinol (THC), the compound in marijuana that produces intoxication. That reduced blood vessel function could increase the chances of developing atherosclerosis, which causes plaque built-up in the arteries and could result in a heart attack.
“Smoke is smoke,” senior author Matthew Springer, a cardiovascular researcher and associate professor of medicine in the UCSF cardiology division, told Dennis Thompson of HealthDay News. “Both tobacco and marijuana smoke impair blood vessel function similarly. People should avoid both, and governments who are protecting people against secondhand smoke exposure should include marijuana in those rules.”
“Marijuana for a long time was viewed as a relatively innocuous drug, but a lot of that came from a lack of information,” added Dr. Stephen Thornton, a toxicologist and medical director of the Poison Control Center at the University of Kansas Hospital. “Now, as more and more people are using it, we’re finding more and more detrimental effects. People just need to be cautious.”
Currently, medical marijuana use is legal in 23 states and Washington DC, and recreational use of the drug is permissible in Alaska, Colorado, Oregon, Washington and the District of Columbia, Thompson said. The US Surgeon General’s office reported in 2014 that secondhand tobacco smoke is responsible for approximately 34,000 premature deaths due to heart disease in nonsmokers.
Springer and his colleagues report that marijuana and tobacco are chemically similar except for THC, and the fact that the rodents experienced a reduction in blood vessel function in THC-free marijuana suggests that the compound itself is not responsible for the effect. Previous studies have found the same is true with nicotine in cigarettes.
In their research, the UCSF scientists used a modified cigarette smoking machine to expose rats to the marijuana smoke, then used a high-resolution ultrasound machine to measure the function of their main leg artery. Blood vessel dilation was recorded both before exposure to the smoke, 10 minutes afterwards, and again 40 minutes post-exposure. Separate tests were conducted with THC-free marijuana and plain air.
No difference in blood vessel function was detected when the rats were exposed to plain air, the authors said. While previous tobacco studies found that blood vessel function returned to normal 30 minutes after exposure, it had not normalized when measured 40 minutes after exposure in the marijuana study, they added.
Springer told Thompson that he came up with the idea for the study, which has not yet been peer-reviewed and was funded by the National Institute on Drug Abuse and the Elfenworks Foundation, while attending a Paul McCartney concert at which cannabis consumption was rampant.
“We were already studying the effect of secondhand tobacco smoke on vascular function, and in the middle of the concert, a bunch of people started lighting up. My first instinct was to say they can’t do that here. But then I realized it was marijuana,” he told the HealthDay reporter. “I think if people started lighting cigarettes in the middle of a stadium, people would tell them to stop. But because they were smoking marijuana, it was OK.”
“Tobacco smoke and marijuana smoke both contain thousands of chemicals, many of which are toxic,” Springer added, noting that government officials should review laws governing indoor and/or outdoor smoking to go back and see if they specifically prohibit tobacco use, or if they would also apply to marijuana smoke.
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