In a small sample of young children in New York City, 20.8% had detectable marijuana metabolites in their urine, with higher rates among those exposed to household tobacco smoke.
Pediatricians, public health officials, parents in multiunit housing
20.8% of children aged 0-3 had detectable marijuana metabolites in their urine
What the researchers found
Among 53 children aged 0-3 years, 20.8% had detectable urinary COOH-THC (a marijuana metabolite), and children with high tobacco smoke exposure were significantly more likely to test positive (p<0.01).
Why it matters
Objective biomarker evidence that young children are absorbing marijuana smoke, even in a state where recreational use was then illegal, underscores that secondhand exposure in shared living spaces is a measurable public health concern.
The numbers in context
53 children; 20.8% had detectable COOH-THC; 90.2% had detectable cotinine; 34.8% of children in housing allowing smoking had detectable COOH-THC vs 13.0% in smoke-free housing; high tobacco exposure significantly associated with COOH-THC detection (p<0.01).
How the study worked
Cross-sectional study collecting urine samples from children at well-child visits or inpatient stays at Mount Sinai (2017-2018), analyzed for cotinine and COOH-THC with parent surveys.
What this study cannot tell us
Very small sample size (53 children); convenience sample from a single hospital; cross-sectional design; cannot determine health effects of detected levels.
How to read the evidence
Small convenience sample provides preliminary biomarker evidence requiring replication in larger studies.
When this study was published
Urine samples collected 2017-2018, when recreational marijuana was illegal in New York.
The bigger picture
As more jurisdictions legalize recreational cannabis, these biomarker data provide objective evidence that secondhand marijuana smoke reaches children, which could inform smoke-free housing and public health policies.
Questions still open
- At what urinary concentration of COOH-THC might health effects become concerning for young children? Would smoke-free housing policies reduce detectable metabolite levels?
Common questions
How were children exposed to marijuana smoke?
Does detecting marijuana metabolites mean the children are harmed?
Read the original research
Secondhand marijuana exposure in a convenience sample of young children in New York City.
Pediatric research, 89(4), 905-910
Citation
Sangmo, Lodoe; Braune, Tanya; Liu, Bian; Wang, Lanqing; Zhang, Li; Sosnoff, Connie S; Blount, Benjamin C; Wilson, Karen M. (2021). Secondhand marijuana exposure in a convenience sample of young children in New York City.. Pediatric research, 89(4), 905-910. https://doi.org/10.1038/s41390-020-0958-7
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