Secondhand Marijuana Smoke Becoming Rising Health Concern for Children

Karen M. Wilson, M.D

Urine samples showed traces of a metabolite of THC in 16% of children tested. [NIH] 

A new study to be presented at the Pediatric Academic Societies 2016 Meeting will report that one in six infants and toddlers admitted to a Colorado hospital with coughing, wheezing, and other symptoms of bronchiolitis tested positive for marijuana exposure.

The study, "Marijuana Exposure in Children Hospitalized for Bronchiolitis," recruited parents of previously healthy children between 1 month of age and 2 years old who were admitted to Children's Hospital Colorado (CHC) between January 2013 and April 2014 with bronchiolitis, an inflammation of the smallest air passages in the lung. 

The parents completed a questionnaire about their child's health, demographics, exposure to tobacco smoke, and, as of October 2014, whether anyone in the home used marijuana. Marijuana became legal in Colorado on January 1, 2014.

Of the children who were identified as having been exposed to marijuana smokers, urine samples showed traces of a metabolite of tetrahydrocannabinol (THC), the psychoactive component of marijuana, in 16% of them. The results also showed that more of the children were THC positive after legalization (21%, compared with 10% before), and nonwhite children were more likely to be exposed than white children.

The findings suggest that secondhand marijuana smoke, which contains carcinogenic and psychoactive chemicals, may be a rising child health concern as marijuana increasingly becomes legal for medical and recreational use in the U.S.,said lead researcher Karen M. Wilson, M.D., an associate professor of pediatrics at the University of Colorado School of Medicine and section head at CHC. Most states with legal marijuana do not restrict its combustion around children, she said.

"Our study demonstrates that, as with secondhand tobacco smoke, children can be exposed to the chemicals in marijuana when it is smoked by someone nearby," Dr. Wilson said. "Especially as marijuana becomes more available and acceptable, we need to learn more about how this may affect children's health and development." In the meantime, she said, "marijuana should never be smoked in the presence of children."