Study Examines Children’s Exposure to Secondhand Cannabis Smoke

Image | adobe.stock/Michael

In a recently published study, researchers sought to examine the exposure of in-home secondhand cannabis smoke (SHCS) in children, measured by urinary biomarkers (1). The cross-sectional study, “Exposure to Secondhand Cannabis Smoke Among Children,” was published January 23, 2025, in JAMA Network Open.

Researchers analyzed data from the 2012-2016 randomized clinical intervention, Project Fresh Air (PFA), which aimed to reduce indoor fine particulate matter. This study included 275 children under 14 years old, and the household was required to have at least one adult tobacco smoker. The urinary biomarkers were examined in 2022. The study assessed the cannabinoids (-)-trans-Δ⁹-tetrahydrocannabinol (THC), which is metabolized to 11-hydroxy-Δ⁹-tetrahydrocannabinol (OH-THC), which is further metabolized to 11-nor-9-carboxy-Δ⁹-tetrahydrocannabinol (COOH-THC), and noted that all three can be used for biomarkers for cannabis exposure.

In the households, an air particle monitor was installed, which continuously counted fine air particles, along with a passive air nicotine dosimeter. Project staff conducted an interview after seven days with the parent or guardian on particle generating activities within the past seven days. The question, “How often in the past 7 days did anyone smoke medicinal or recreational marijuana in your home?” was asked of parents and guardians in order to assess in-home cannabis smoking. The parent or guardian collected the urine sample, which was transported by staff to the laboratory.

Results from the study included:

• 29 households reported in-home cannabis smoking within the past seven days
• 75 children had detectable urinary cannabinoids
• In households that had reported cannabis smoking, 20 of 29 children had detectable THC equivalents (TTE levels)
• In households that did not report cannabis smoking, 40 of 169 children had detectable TTE levels
• The odds of detecting cannabis biomarkers from children in households reporting cannabis smoking was five times the odds of households that did not report cannabis smoking

Ultimately, researchers concluded that in-home cannabis smoking and secondhand cannabis smoke exposure to children are related, and called for further studies. “Approaches to decrease in-home cannabis smoking, especially in households with children, should be tested,” the conclusion stated. “Investigation of how evolving cannabis regulatory environments impact in-home smoking patterns and potential increased child SHCS exposure is essential. Lastly, more information is needed on the long-term health risks of SHCS exposure.” The discussion section included the suggestion establishing rules again cannabis smoking in house and indoors to protect children’s health.

Limitations of the study included potential underreporting of in-home cannabis smoking, the focus on tobacco rather than cannabis, a lack of specification of method of cannabis smoking, and missing data from some households. The study was also noncausal, and is possibly limited in its generalization to other populations. The researchers also noted that further studies should measure effects of cannabis exposure in locations outside the home as well.

Reference

1. Tripathi, O.; Parada Jr, H.; Sosnoff, C.; Matt, GE.;. Quintana, PJE.; Shi, Y.; Liles, S.; Wang, L.; Caron KT.; Oneill, J.; Nguyen, B.; Blount, BC; Bellettiere, J. Exposure to Secondhand Cannabis Smoke Among Children. JAMA Netw Open. 2025. DOI: 10.1001/jamanetworkopen.2024.55963