A new study from the University of California, San Francisco, has found that breathing secondhand smoke from marijuana may be just as bad for the health as cigarette smoke, causing heart and blood vessel damage. The reduced functioning of the blood vessels may raise the risks of a person developing atherosclerosis, which can lead to increased heart attack risk. Atherosclerosis is a condition that causes plaque to build up in the arteries, a condition known as hardening of the arteries, which narrows them and restricts blood flow.
Senior study author Matthew Springer says that hanging out in a room where people are smoking a lot of pot may harm blood vessels. He says that there is “no reason to think marijuana smoke is better than tobacco smoke,” and advises that people avoid them both.
In the study, rats were exposed to secondhand marijuana smoke and their blood vessel function measured 10 minutes before and 40 minutes later. Blood vessel function dropped by 70 percent after a 30-minute exposure. The rats were also exposed to marijuana secondhand smoke that did not contain tetrahydrocannabinol (THC), the active ingredient in cannabis. The same reduction in blood vessel function occurred, proving that the effect was not due to the presence of THC.
With secondhand smoke exposure from tobacco, the reduced blood vessel effect generally normalizes within 40 minutes. This was not the case with marijuana secondhand smoke, which caused even greater bad effects than cigarette smoke.
As more states are legalizing recreational marijuana, safety has become a growing concern. Dr. Stephen Thornton, medical director and toxicologist at the University of Kansas Hospital’s Poison Control Center, said that for a long time marijuana was viewed as a “relatively innocuous drug.” As more people are using it now they are finding more detrimental effects. According to the U.S. Surgeon General’s 2014 report on the consequences of smoking, secondhand tobacco smoke causes approximately 34,000 premature deaths from heart disease among nonsmokers in the U.S. every year.
Springer said that he came thought of the study while attending a Paul McCartney concert, when people started lighting up all around him. Cigarettes would not be allowed in such a situation, but because it was pot people thought it was okay. Springer and his group were already studying the effects on vascular function from secondhand tobacco smoke.
According to Springer, both marijuana and tobacco smoke contain thousands of chemicals, and many are toxic. Of the more than 7,000 chemicals produced by burning tobacco, hundreds are toxic and 70 are linked to cancer. However, other studies have shown that some of the chemicals found in marijuana can play a major role in protecting the nervous system against multiple sclerosis and reducing tumor growth in cancer patients.
Springer recommends that laws regarding smoke-free areas be looked at to see if they specifically cite tobacco use or might be able to apply to marijuana smoke as well, particularly since research has now indicated that secondhand smoke from marijuana and from cigarettes are equally bad for health. The study was presented on Sunday in Chicago at the American Heart Association’s Scientific Sessions 2014.
By Beth A. Balen