New research finds that exposure to secondhand marijuana smoke may cause significant physical harm to your loved ones, friends and acquaintances. In a study presented in November 2014 to the American Heart Association, researchers from UC San Francisco concluded that exposure to secondhand marijuana smoke is linked to a decline in blood vessel health that may set the stage for hardening of the arteries and the onset of a heart attack.
Marijuana Consumption and Addiction
Close to 20 million American preteens, teenagers and adults are monthly marijuana consumers, according to figures compiled by the federal Substance Abuse and Mental Health Services Administration. Like all other substances that produce a sensation called euphoria by changing the chemical balance in the brain’s pleasure center, marijuana/cannabis can act as a catalyst for the onset of addiction. Evidence gathered by the National Institute on Drug Abuse indicates that a person who consumes the drug on a daily or near-daily basis has a one-in-four to one-in-two chance of developing such an addiction at some point in his or her lifetime. The symptoms of marijuana/cannabis addiction can overlap substantially with the symptoms of marijuana/cannabis abuse, the other condition included in the definition of cannabis use disorder.
Marijuana has a known ability to seriously alter the function of other critical systems inside the body besides the brain. For example, heart rate changes associated with the consumption of the drug make users temporarily about 300 percent more likely to experience a heart attack. The increased risks for a heart attack also stem partly from the changes that marijuana/cannabis triggers in the health of the body’s blood vessels (i.e. arteries and veins).
The term secondhand smoke is usually used to describe the particles and gases emitted into the air by people who smoke cigarettes. In the case of cigarettes, this smoke contains several hundred chemicals capable of damaging some aspect of human health and well-being. Exposure to secondhand cigarette smoke is clearly linked to increased chances of experiencing strokes, heart attacks and other forms of cardiovascular (heart and blood vessel) disease. Exposure to this smoke also significantly increases the odds that any given person will develop lung cancer. Unfortunately, in the U.S. tens of thousands of people who have never directly consumed a cigarette will die from secondhand smoke-related lung cancer or cardiovascular disease each year.
Impact of Secondhand Marijuana Smoke
In the study presented to the American Heart Association, the UC San Francisco researchers used laboratory experiments on rats to explore the health impact of exposure to secondhand marijuana smoke. During the study, three groups of rats were exposed, respectively, to marijuana smoke that contained the active cannabis ingredient THC (tetrahydrocannabinol), marijuana smoke that did not contain THC and air that did not contain any smoke. The researchers examined the blood vessel health of each group of animals before exposure to marijuana smoke or plain air, as well as 10 minutes and 40 minutes after exposure.
After completing their experiments, the researchers found that, within half an hour, the blood vessel health of the rats exposed to marijuana smoke declined by a precipitous 70 percent. The drop in function was equal in rats exposed to THC-containing smoke and rats exposed to marijuana smoke that did not contain THC. Forty minutes after secondhand marijuana smoke exposure, the rats’ blood vessels had not returned to normal function. This is an important finding, since the blood vessels of people exposed to secondhand cigarette smoke generally start to regain their normal function within half an hour of exposure.
The study’s authors believe that the decline in blood vessel function they observed may be enough to boost the risks that a person exposed to secondhand marijuana smoke will develop atherosclerosis (hardening and narrowing of the arteries), one of the known preconditions for the onset of a heart attack. The authors also note that, regardless of the fact that it contains a different main ingredient (THC), marijuana produces smoke that strongly resembles cigarette smoke in most important respects. They point toward a need for further research to explore the potential consequences of secondhand marijuana smoke exposure in humans.