With marijuana use exploding in line with a legalization movement sweeping the nation, many people are pitching cannabis as an all-natural medicine to help with medical conditions or a “safe” alternative to traditional intoxicants like alcohol.

But scientists and doctors say things aren’t that simple — and a belief that exposing children to marijuana, either directly or indirectly, is harmless isn’t supported by the facts.

US News reports on a December study published in the journal Pediatric Research examining Colorado children who were diagnosed with a lower respiratory infection called bronchiolitis. Of the 43 children studied, 16 percent had been exposed to marijuana smoke, and many had also been exposed to tobacco smoke.

Dr. Karen Wilson, the division chief of general pediatrics at Mount Sinai Hospital in New York City, had previously studied the risks of secondhand tobacco smoke in children in Colorado. She reported that her team had seen a change in attitudes about marijuana smoke.

“As we were asking the families whether their children were exposed to tobacco smoke, more and more of them started to say, ‘Oh, no, we don’t smoke tobacco – we only smoke marijuana because that’s natural,'” she told US News.

Wilson added, however, that her researchers’ anecdotal evidence suggested that marijuana exposure in children was already an increasing problem before the state legalized marijuana in 2014.

Studies are inconclusive on the relative risk of secondhand marijuana smoke compared to secondhand tobacco smoke. Research published in 2006 and 2014 found little to indicate that marijuana smokers took on the same risk of lung cancer as cigarette smokers, though the reason for that lower risk remains unclear — is it because THC shows signs of fighting cancer cells in the body? Is it because marijuana smokers tend to smoke much less overall than tobacco smokers?

Even the question of a “contact high” seems to be based more in apocrypha than in hard science: A Johns Hopkins study found that nonsmokers could experience some intoxication symptoms and even show a positive drug test — if they were in an unvented space with pot smokers. In other words, if your friends are hotboxing the car, don’t get in with them unless you actually want to get a little high.

Still, US News speaks to doctor who say the message on marijuana, pregnancy and children is clear: Don’t mix them. Marijuana has been linked to negative developmental consequences in infants and young children, and smoking anything while pregnant can carry significant risks for a fetus.

To read more about secondhand smoke, head over to US News and the Orange County Register.

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