Second hand marijuana smoke can cause serious damage

By Dr. Ananya Mandal, MDMar 19 2018

Researchers have shown that even a minute of exposure to second hand marijuana smoke exposure can be dangerous for the blood vessels and raise the risk of several diseases. The study titled “One Minute of Marijuana Secondhand Smoke Exposure Substantially Impairs Vascular Endothelial Function,” was published recently in theJournal of American Heart Association.

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Second hand smoke has been a problem for some time now. Second hand cigarette smoke has been under the scanner but second hand marijuana smoke is also equally or even more dangerous find researchers. Most people mistakenly believe the second hand marijuana smoke is harmless. As marijuana is being increasingly legalized in several states, there should be laws in place to curb smoking pot in public places just like traditional smoking.

Pot smoke is considered to be benign mainly because there is little evidence or scientific work on the effects of this kind of second hand smoke write researchers. Lead author Matthew Springer, a Professor at the University of California, San Francisco, that the damage caused by marijuana second hand smoke lasts three times longer than tobacco smoke. He said, “We in the public health community have been telling them for decades to avoid inhaling secondhand smoke from tobacco… We have not been telling them to avoid inhaling secondhand smoke from marijuana… it’s because we just haven’t known. The experiments haven’t been done.”

The team looked at the effects of marijuana on the blood vessel walls or the vascular endothelium. For this study they looked at the femoral artery sections in rats to check for the flow dilatation. Typically both tobacco and marijuana smoke impair the dilatation of the blood vessels. Before and after exposure to marijuana smoke were measured. They noted that even a minute of exposure to this smoke can impair the blood flow in the femoral artery. They also tested with second hand smoke from traditional cigarettes. The team noted that the damage caused by either of the two is similar. What was different was that with marijuana smoke, the recovery of the endothelium was slower after the exposure was stopped -  three times slower.

The team investigated the effects of the second hand marijuana smoke and found that the dilatation of the blood vessels when exposed to marijuana second hand smoke is impaired much like with tobacco smoke. This subsides within 25 minutes of exposure with tobacco smoke. However the impaired blood flow remained same for at least 90 minutes after exposure to marijuana smoke they found.

The authors concluded that one minute of marijuana second hand smoke “substantially impairs endothelial function in rats for at least 90 minutes, considerably longer than comparable impairment by tobacco (second hand smoke)”.