Children exposed to marijuana smoke may absorb traces of the drug

Some children exposed to marijuana smoke have traces of a metabolite of THC, the main psychoactive component in cannabis, in their urine.

Why it matters

Twenty-three states and the District of Columbia have legalized marijuana for either medical or recreational use, but the impact of secondhand cannabis smoke on children is largely unknown. This was the first study to use a new, highly sensitive test to document secondhand marijuana smoke exposure in children, said lead investigator Dr. Karen M. Wilson, an associate professor of pediatrics at the University of Colorado’s medical school.

The nitty gritty

Researchers took urine samples from 43 infants and toddlers who were hospitalized for bronchiolitis in Colorado. Sixteen percent of the children had detectable levels of a THC metabolite in their urine.

What they’re saying

The urine test is very sensitive, picking up even extremely small traces of the THC metabolite. The levels found in the children’s urine “are not likely to be associated with intoxication or impairment,” said Ryan Gregory Vandrey, who studies the pharmacology of cannabis at John Hopkins University. But these tests are just a snapshot of how much was in their urine that day: There’s no way to tell how much marijuana the child was exposed to overall, or for how long, he said, and any exposure in children is worrisome.

Experts are concerned about the neurocognitive impact of drug exposure during this critical period of development, said Judith T. Zelikoff, a professor in the department of environmental medicine at the New York University School of Medicine. (All the children studied were between 1 month and 2 years old.)

And there are concerns about secondhand exposure to marijuana smoke. “We know what’s in the marijuana smoke,” Zelikoff said. “We are concerned about it because it has got many of the same ingredients or components in the smoke as tobacco smoke.”

But keep in mind

This study is just a snapshot, presented at a pediatric conference and not yet peer-reviewed.

While the authors conclude that “one in six young children in our study was exposed to marijuana,” it’s important to be wary of alarmist headlines, said Vandrey. The sample size here is extremely small.

The bottom line

Parents who smoke marijuana need to be aware that their children are being exposed to drug compounds as well as the toxic effects of secondhand smoke. Until more robust studies determine the impact of this exposure, it’s best to take a conservative approach and avoid smoking marijuana near children.