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A recent study suggests that breastfeeding mothers who use marijuana may inadvertently expose their infants to THC, the psychoactive compound in cannabis, through breast milk. This finding is worrying as there is limited research on the impact of such drugs on babies.

THC could be present in breast milk

Researchers from Washington State University found low levels of THC in breast milk. However, they observed inconsistency in THC concentrations, making it unpredictable when THC levels would peak and decline after cannabis use. Even after 12 hours, THC remained detectable, peaking and dropping at different times.

The popularity of cannabis is rising due to its legalization in many states for recreational use. The study published in Breastfeeding Medicine found that infants of mothers testing positive for THC in breast milk consumed an average of 0.07 milligrams of THC daily. This amount is comparatively low; for instance, a typical low-dose edible contains around two milligrams of THC. Although researchers suspect potential negative health impacts on infants from THC exposure, conclusive evidence is lacking.

According to lead author and biological anthropologist at Washington State University, Courtney Meehan breastfeeding individuals should be mindful that cannabis use may result in infants ingesting cannabinoids through breast milk. However the potential effects of this on infant development are currently unknown.

Lipids in breast milk dissolve lipophilic cannabinoids

The study examined the breast milk of 20 breastfeeding mothers who admitted to using cannabis. These mothers had infants under six months-old and reported their cannabis use patterns. Milk samples were collected after abstaining from cannabis for at least 12 hours and then at regular intervals after use. Cannabis residues persisted in breast milk beyond the 12-hour abstinence period.

Human milk contains lipids, and cannabinoids, being lipophilic, dissolve in these lipids. This suggests that cannabinoids, such as THC, may accumulate in breast milk and thus in infants who consume it. However, it’s uncertain when THC levels peak in a breastfeeding mother’s milk. Single-use cannabis consumers experienced peak THC levels around 30 minutes to 2.5 hours post-consumption, while frequent users showed a gradual increase in THC concentrations throughout the day.