Maternal cannabis use may expose infants to harmful compounds through breast milk

by Levi McGarry, Washington State University

edited by Swati Mestri, reviewed by Andrew Zinin

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Infants whose mothers smoked cannabis while breastfeeding had volatile organic compounds in their urine, a recent study shows.

The study, conducted at Washington State University and published in the International Journal of Environmental Research and Public Health, is the first to investigate whether infants breastfed by women using cannabis show evidence of exposure to VOCs, which are chemicals that evaporate easily, are found in many products and may have harmful effects on human health.

This is the latest publication on cannabis use during lactation and human milk composition by the research team led by Courtney Meehan, dean of the College of Arts and Sciences and professor of anthropology.

"When we surveyed women using cannabis during lactation a couple of years ago, we learned that many mothers use cannabis in lieu of other pharmaceutical drugs because they view using cannabis as safer," said Meehan. "But data do not exist regarding the risk, or lack thereof, of cannabis use during lactation. Women are making these decisions without complete information."

Previous studies have shown that some VOCs can harm long-term human health, but despite increases in maternal cannabis use during the perinatal period, little is known about whether infants are exposed to VOCs when their mothers breastfeed them.

"Some VOCs affect human health, so infants should avoid exposure, if possible," said Meehan. "But we do not know whether the concentrations of VOCs found in our study are high enough to impact infant health."

The study enrolled breastfeeding women living in Washington or Oregon who reported smoking or vaping cannabis more than once a week. After providing demographic and cannabis use data, the participating mothers collected milk and infant urine samples throughout a study day, starting with a baseline sample after 12 hours of abstaining from cannabis.

The mothers then used cannabis as they normally would, and additional milk and infant urine samples were collected at predetermined time intervals after cannabis use.

At the end of each study day, study personnel collected milk and urine samples from the participating mothers, storing samples until they could be analyzed by the Division of Laboratory Sciences at the Centers for Disease Control and Prevention (CDC).

There were detectable levels of 24 VOC metabolites across the urine samples, with all infants having at least one sample with detectable VOC metabolite concentrations. These concentrations were higher following cannabis use than at baseline, after abstention.

"If a mother's milk is an exposure pathway to these compounds, then it is critical for doctors to have that information to inform their patients," said Meehan. "It's also critical for patients to be able to access that information to make data-informed decisions about their use of cannabis during lactation."

While the current study illuminates a potential VOC exposure pathway for infants, Meehan emphasizes that further research is needed to evaluate the potential health risks to infants from second- and thirdhand cannabis smoke exposure and possible long-term health outcomes.

"We are in a period of time where cannabis use is becoming more normalized, to the point where the societal acceptance is rapidly outpacing the ongoing research about cannabinoid exposure and impacts," said Meehan. "There has been so little research conducted on cannabis use during lactation that women and families are without information to help them make critical decisions."

Publication details

Shelby Samartino et al., Volatile Organic Compound Metabolites Are Found in the Urine of Breastfed Infants Whose Mothers Use Cannabis: The Lactation and Cannabis (LAC) Study, International Journal of Environmental Research and Public Health (2026). DOI: 10.3390/ijerph23070905

Journal information: International Journal of Environmental Research and Public Health

Key medical concepts

Volatile Organic Compounds

Clinical categories

PediatricsChildren's healthObstetrics & gynecologyWomen's healthReproductive health Provided by Washington State University Who's behind this story?

Swati Mestri

Swati Mestri holds a bachelor's degree in Electronics Engineering and has worked as a content editor since 2019. She has experience editing research documents across technology, health care, and materials science, and has a particular interest in technology and space. Full profile →

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