Preliminary research presented at the American Heart Association’s (AHA) Scientific Sessions 2014 reveals that breathing secondhand marijuana smoke may damage the heart and blood vessels as much as secondhand cigarette smoke.

According to the AHA, blood vessel function in lab rats dropped 70% after 30 minutes of exposure to secondhand marijuana smoke in the study. In addition, even when the marijuana had no THC, which is the compound in marijuana that produces intoxication, blood vessel function was still impaired.

For the study, researchers used a modified cigarette smoking machine to expose rats to marijuana smoke. A high-resolution ultrasound machine measured how well the main leg artery functioned. Researchers recorded blood vessel dilation before smoke exposure and 10 minutes and 40 minutes after smoke exposure, as indicated on the AHA news release. Blood vessel dilation was recorded before smoke exposure as well as 10 minutes and 40 minutes following smoke exposure.

In addition, the researchers also conducted separate tests with THC-free marijuana and plain air. The result showed no difference in blood vessel function when the rats were exposed to plain air.

Matthew Springer, PhD, senior author of the study, says now that marijuana is becoming increasingly legalized in the United States, its effect on others is a growing public health concern. Springer adds, “If you’re hanging out in a room where people are smoking a lot of marijuana, you may be harming your blood vessels. There’s no reason to think marijuana smoke is better than tobacco smoke. Avoid them both.”

The AHA news release notes more research is needed to determine if secondhand marijuana smoke has other similar effects to secondhand cigarette smoke in humans.

Source: AHA