Reducing In-Home Cannabis Smoking Could Significantly Cut Children's Exposure to Toxic Secondhand Smoke: JAMA

"Given that young children spend a large portion of their time indoors, minimizing in-home cannabis smoking could significantly reduce their exposure to the harmful and carcinogenic chemicals present in cannabis smoke," the researchers wrote.

The research underlines that children, particularly young ones, spend a considerable amount of their time indoors, making them especially vulnerable to the toxic and carcinogenic chemicals present in secondhand cannabis smoke. As cannabis use becomes more widely accepted and legal in several regions, the health risks associated with exposure to secondhand smoke are raising increasing concerns among public health experts. Considering this, Osika Tripathi, San Diego State University, School of Public Health, San Diego, California, and colleagues aimed to examine the relationship between in-home cannabis smoking and the presence of urinary cannabinoids in children living in the household.

For this purpose, the researchers used baseline data from Project Fresh Air, a 2012-2016 clinical trial conducted in San Diego County, California, which included households with children under 14 years and at least one adult tobacco smoker. Children’s urine samples were analyzed in 2022 for cannabis biomarkers, including Δ9-tetrahydrocannabinol (THC) and its metabolites. In-home cannabis smoking was assessed through parent reports, air particle counts, and daily cannabis smoking events. The study found a significant association between in-home cannabis smoking and the detection of cannabis biomarkers in children’s urine, with greater exposure linked to higher urinary THC equivalents.

Key Findings:

• 275 children were included in the analysis, with a mean age of 3.6 years. The cohort consisted of 144 males (52.4%), 38 Black children (13.8%), 132 Hispanic children (48.0%), and 52 White children (18.9%).
• Twenty-nine households (10.6%) reported in-home cannabis smoking in the past 7 days.
• Seventy-five children (27.3%) had detectable urinary cannabinoids.
• The odds of detectable TTE in children’s urine were significantly higher in households with in-home cannabis smoking compared to those without (OR, 5.0).
• For each additional daily cannabis smoking event, the odds of detectable TTE increased (OR, 2.5).
• Although TTE levels were higher among children exposed to more daily cannabis smoking events, the increase per event (35.68%) was not statistically significant.

The study indicates a clear link between in-home cannabis smoking and children's exposure to secondhand cannabis smoke.

"Strategies aimed at reducing in-home cannabis smoking, particularly in households with children, should be explored. It is also crucial to investigate how changes in cannabis regulations affect in-home smoking patterns and potentially increase child SHCS exposure. Additionally, further research is needed to better understand the long-term health risks associated with SHCS exposure," the researchers concluded.

Reference:

Tripathi O, Parada H, Sosnoff C, et al. Exposure to Secondhand Cannabis Smoke Among Children. JAMA Netw Open. 2025;8(1):e2455963. doi:10.1001/jamanetworkopen.2024.55963