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Spokane, Washington  Est. May 19, 1883

WSU study finds that THC lingers in breastmilk

A customer looks at marijuana buds at the Proper Cannabis dispensary in Kansas City, Mo., on March 17.  (Brendan Smialowski/Getty Images of North America/TNS)

Traces of the psychoactive cannabis component THC can show up in breast milk, a new study out of Washington State University found.

“Breastfeeding parents need to be aware that if they use cannabis, their infants are likely consuming cannabinoids via the milk they produce, and we do not know whether this has any effect on the developing infant,” said WSU study author Courtney Meehan, a biological anthropologist.

The research in testing breast milk found that the amount of THC detected was low – an estimated average of 0.07 mg per day. A common low-dose edible cannabis product has 2 mg of THC.

Researchers also found that there was no consistent time when the THC in breast milk peaked and started to decline. That’s in contrast to a peak in alcoholic drink levels that are usually highest in breast milk 30 to 60 minutes after a woman consumes, and generally detected for about two to three hours per drink, according to the Centers for Disease Control and Prevention.

The CDC recommends that breastfeeding mothers abstain from both cannabis and alcohol.

What’s next on the researchers’ radaris whether the small THC amount has any impact on an infant. Meehan said the group has another research project that’s analyzing data on infant development related to cannabis use during lactation. The group hopes to release data by the end of this year.

“We have participants who are actually part of this recent study, but we also have a control group enrolled, so we have a larger component of the study we just published,” Meehan said.

Many of the breastfeeding moms have told the same researchers – for a related study – that their cannabis use most often is based on needs to manage anxiety, mental health issues or chronic pain. The mothers often chose cannabis over using other medications for those conditions, because they felt marijuana was safer.

The recent study included 20 breastfeeding mothers in Washington and Oregon who used cannabis. The participants, who all had infants younger than six months, provided detailed reports on their cannabis use.

The women collected milk after abstaining from using cannabis for at least 12 hours, and then at regular intervals after use, the researchers said. All was done in their own homes, at a time of their choosing and with cannabis they purchased themselves.

The researchers then analyzed the milk for cannabinoids. They found that the milk produced by these women always had detectable amounts of THC, even when the mothers had abstained for 12 hours.

People had different peak THC concentrations in their milk, according to the findings. For participants who used cannabis only one time during the study, cannabinoids peaked about 30 minutes to 2½ hours after use and then started to decline. For participants who used multiple times during the study, the majority showed a continual increase in concentrations across the day.

Lipids in milk might be part of the reason, because cannabinoids dissolve in those lipids.

“This may mean that cannabinoids like THC tend to accumulate in milk, and potentially in infants who drink it,” Meehan said.

“Milk has a lot of lipids in it, and because of that, it could be a repository for cannabinoids, meaning you might end up having them, in essence, stored. But we didn’t know the answer to that. The variation in when the THC peaked in milk is really a fascinating question, whether it is simply based on use pattern or whether there are variations in maternal characteristics that we don’t know yet.”

Lead author Elizabeth Holdsworth, working on the study while a WSU post-doctoral researcher, also referred to the THC variation. Now at Ohio State University, Holdsworth said in a news release, “if you’re trying to avoid breastfeeding when the concentration of THC peaks, you’re not going to know when THC is at its peak in the milk.”

Meehan said that past clinical trials on medication impacts have typically excluded women, and “breastfeeding women in particular.”

“It’s often quite challenging for women to access the information they need to determine what they should do while they’re breastfeeding,” she said.

Meehan said the researchers embarked on the study because cannabis use is increasing among reproductive-aged women.

“And so with that increase, there is a growing need to better understand the potential effects on human milk composition and its potential – or lack thereof – effects on developing infants.

“Unfortunately, there is not a lot of research out there, so parents have been in a research desert trying to find the necessary information that they need to be able to make their choices. They’re often making choices between two unknowns or between taking something and not.”