According to this article on NPR.org, this study looked at children, ages 1 month to 2 years, who were hospitalized for bronchiolitis. They all lived in Colorado, a state where recreational marijuana is legal, and their urine samples were sent to the Centers for Disease Control and Prevention for a screening that detects low levels of marijuana metabolites.
Unsurprisingly, 75 percent of the children whose caregivers indicated they’d been in a home where they’d been exposed to cannabis had traces of marijuana in their urine.
Wilson concluded that “There is a strong association between those who said there was someone in the home who used marijuana or a caretaker who used marijuana and the child having detectable marijuana levels.”
“Our hypothesis is that it is not good for kids,” she says.