Elephant Circle’s involvement
As many of you know, Colorado has a law that says that an infant who tests positive for exposure to a Schedule I or Schedule II substance is an automatic finding of child abuse and neglect. When we heard about Dr. Teresa Baker and Dr. Thomas Hale’s research, we worried that participation in their study could land participants in hot water with Child Protective Services. So we offered to think through that issue with them with great success! Their home institution, Texas Tech, helped them navigate the human subjects’ approval process with lessons learned from the early days of HIV research. The result was an anonymous consent process, which allowed participation without worry of state involvement. Hurrah!
Our involvement continued through data collection and we were specifically involved in subject recruitment in two ways. First, our work supporting perinatal families who use cannabis provided us access to a unique population and previously established relationships that allowed us to encourage and support participation. Further, many lactation and health care professionals worried that recruiting subjects could jeopardize them professionally because of their license and/or board certification. One of the advantages of Elephant Circle being a small, independent organization is that we could lean into this risk more fully. As a result, we found ourselves creating opportunities for folks to participate in order to boost the numbers. It was hard work!
In case you don't have access to the paper itself, we wanted to make sure you could access the highlights! Here is our summary of the paper and its findings.
The goal of the study
To accurately determine the transfer of Delta-9-Tetrahydrocannabinol (D9-THC, the primary psychoactive molecule) and its metabolites (11-OH delta-9-THC and 9-carboxy delta-9-THC) into human milk at 20 minutes, 1 h, 2 h, 4 hours after smoking 0.1 g of cannabis containing 23.3% THCA. A baseline sample was also collected 2 hours prior to cannabis consumption. (For a review of the molecules involved in cannabis metabolism, please refer to this guide.)
Eight lactating women participated in this study. All participants were 2-5 months postpartum and were not supplementing with artificial milk substitutes or solids. Half of the participants reported they smoked cannabis infrequently and one smoked cannabis 7-10 times during the prior week (3 participants did not answer these questions). Participants were not taking any other medications.
Baseline D9-THC levels in human milk
Prior to cannabis consumption, D9-THC levels were exceedingly low in 6 of 8 subjects (< 2 ng/mL), suggesting that most subjects were able to abstain from using marijuana for 24 hours before the collection of the samples. The other two subjects had low but measurable levels of D9-THC (5.8 and 15.8 ng/mL) possibly due to residual accumulations of D9-THC from prior heavy use or use close to the start of milk collection.
THC levels after smoking 0.1 g cannabis
D9-THC levels were detected in the human milk as early as 20 mins after smoking and peaked at 1 hour (94 ng/mL, range 12.2 - 420.3 ng/mL) in the milk samples. These data suggest that an exclusively breastfeeding infant ingests 2.5% of the maternal dose (range 0.4-8.7%) and demonstrate that D9-THC levels decline quickly in the breastmilk compartment. By 4 hours after smoking, D9-THC levels were much lower (25.62 ± 6.8 SEM).
These pilot data demonstrate that, after smoking 0.1g of cannabis, the psychoactive molecule D9-THC enters the breastmilk compartment rapidly, peaks at 1 hour and is returning to baseline by 4 hours after consumption. Moreover, despite differences in absolute levels of D9-THC in their milk, THC peaked and declined in a similar timeframe across all participants. Finally, given the very low levels of D9-THC at baseline and the rapid decline after smoking, these data do not support the idea that D9-THC lingers in breastmilk because of its high fat content.
For the nerds out there
Several pharmacokinetic parameters for D9-THC were calculated using the data collected for this paper (n=8). Specifically, the median area under the curve (AUC) was 110.5 ng/h/mL (range: 33.9-744.4), the median average drug concentration across the dose interval (Cavg) was 27.6 ng/mL (8.4-186.1), the median maximum drug concentration across the dose interval (Cmax) was 44.7 ng/mL (12.2-420.3), the median time at which the max occurred (Tmax) was 1 hour (1-2), the median infant dose was 4.1 micrograms/kg/d (1.3-27.9) and the median relative infant dose (RID) was 1.3 (0.4-8.7). Enjoy!
Certainly, further research is needed for a complete understanding of the pharmacokinetics of D9-THC in breastmilk in addition to the clinical implications on cannabis use on parenting and infant neurodevelopment. However, these pilot data suggest that, like alcohol, there may be a day where it is possible to talk to lactating parents about the peak and fall of D9-THC exposure via human milk after smoking cannabis. We certainly aren't there yet, but this paper is a good place to start an evidence-based conversation with well-collected data.
Read the full paper here.