16% of Hospitalized Toddlers in Colorado Had Detectable Marijuana Metabolites in Their Urine | Research

The takeaway

Among 43 children under age 2 hospitalized with bronchiolitis in Colorado, 16% had detectable marijuana metabolites in their urine, with exposure more common in non-white children and those with tobacco smoke exposure.

Parents who use cannabis and have young children.

16% of hospitalized toddlers had detectable marijuana metabolites; 44% of non-white children were exposed

What the researchers found

Researchers tested urine from 43 young children (ages 1 month to 2 years) hospitalized with bronchiolitis in Colorado for marijuana metabolites using highly sensitive LC/MS/MS testing.

16% of samples were positive for COOH-THC (the primary marijuana metabolite), with concentrations ranging from 0.03 to 1.5 ng/mL. Two subjects had levels above 1 ng/mL. The exposure was detected through secondhand marijuana smoke, not intentional administration.

Non-white children had significantly more exposure than white children (44% vs. 9%, p < 0.05). Children with higher tobacco smoke exposure (cotinine > 2.0 ng/mL) were more likely to also be positive for marijuana metabolites (40% vs. 7%, p < 0.01), suggesting households with tobacco smoke are also more likely to expose children to marijuana smoke.

Why it matters

This is one of the first studies to objectively document secondhand marijuana smoke exposure in young children. The 16% positivity rate is concerning given that these children were already hospitalized with a respiratory illness. Whether secondhand marijuana smoke contributed to or worsened their bronchiolitis is unknown but raises important questions.

The numbers in context

43 children tested. 16% positive for COOH-THC. Range: 0.03-1.5 ng/mL. 2 children had levels > 1 ng/mL. 77% male. 52% under 1 year. Non-white children: 44% vs. 9% exposed (p < 0.05). High tobacco exposure: 40% vs. 7% also marijuana-exposed (p < 0.01).

How the study worked

Cross-sectional study of children aged 1 month to 2 years hospitalized with bronchiolitis in Colorado (2013-2015). Parent survey and urine analysis for cotinine (tobacco metabolite) and COOH-THC (marijuana metabolite) using LC/MS/MS with very low detection limits (0.015 ng/mL for COOH-THC).

What this study cannot tell us

Very small sample (43 children). Single-site study in Colorado. Cannot determine whether the marijuana exposure contributed to the bronchiolitis. The detection of metabolites confirms exposure but cannot determine the magnitude, frequency, or route (could be from clothing or surfaces, not just smoke). No comparison to hospitalized children outside legalization states.

How to read the evidence

Preliminary evidence from a small, single-site study with biomarker confirmation.

When this study was published

Published in 2017. One of the first studies to objectively measure secondhand marijuana smoke exposure in children.

The bigger picture

As cannabis legalization expands, secondhand exposure in children becomes a public health concern parallel to secondhand tobacco smoke. This study provides the first biomarker evidence that young children in Colorado are being exposed to marijuana smoke, establishing a baseline for monitoring and motivating research on health effects.

Questions still open

Does secondhand marijuana smoke worsen respiratory illness in young children? What are the developmental effects of chronic secondhand marijuana exposure? Should pediatric screening for marijuana metabolites become routine in legalization states?

Common questions

Can secondhand marijuana smoke affect young children?

This study confirmed that marijuana metabolites can be detected in the urine of young children, proving that secondhand exposure occurs. Whether this exposure causes health problems is still unknown, but the finding raises concerns, particularly since these children were hospitalized with respiratory illness.

How are young children being exposed to marijuana?

Through secondhand smoke in the home. This study found that children in households with tobacco smoke were also more likely to have marijuana metabolites, suggesting these exposures often co-occur. The metabolites detected (COOH-THC) confirm systemic absorption, meaning the children are not just smelling smoke but actually absorbing marijuana compounds.

Read the original research

Detecting biomarkers of secondhand marijuana smoke in young children.

Pediatric research, 81(4), 589-592

View on PubMed ↗Publisher’s paper ↗

Citation

Wilson, Karen M; Torok, Michelle R; Wei, Binnian; Wang, Lanqing; Robinson, Michelle; Sosnoff, Connie S; Blount, Benjamin C. (2017). Detecting biomarkers of secondhand marijuana smoke in young children.. Pediatric research, 81(4), 589-592. https://doi.org/10.1038/pr.2016.261