Title : Infant exposure to cannabinoids via the mother’s milk
Abstract:
Cannabinoids are the primary active compounds in Cannabis sativa, which has been used for over 4000 years as a recreational drug. The main psychoactive constituent of hemp is Δ9-tetrahydrocannabinol (Δ9-THC). In plants, it occurs as the non-psychoactive tetrahydrocannabinolic acid (Δ9-THCA), which is decarboxylated to Δ9-THC upon heating.
Chronic THC use among adolescents is linked to cognitive deficits, increased risk of psychosis/schizophrenia, mood and anxiety disorders, and suicidal behaviors. In adults, excessive cannabis use can lead to mental, gastrointestinal, and cardiovascular problems. As a result, the legal status of cannabis preparations varies among countries, including regions (as of 2025) that have a complete ban on all cannabis products, irrespective of their THC concentration.
Other major phytocannabinoids are generally considered non-psychoactive and are known for their antioxidant and anti-inflammatory properties. They hold promise for treating conditions such as chronic pain, multiple sclerosis, epilepsy, anxiety, cancer, and Parkinson’s disease.
With cannabis preparations legalized in many countries for medical purposes and the recreational use (whether legal or illegal) of cannabis popular worldwide, the risk of offspring exposure to cannabinoids due to maternal consumption prepartum or during breastfeeding is far from negligible. For example, THC is detectable in most milk samples from users, sometimes for up to 6 days after the last use. Other cannabinoids (CBD, CBN, and metabolites) are also detected. Cannabinoids are highly lipophilic, low–molecular–weight compounds that partition into fat-rich media, including milk. Unfortunately, systematic studies of cannabinoids’ partitioning into human breast milk are ethically impossible.
In our study, we examined more than 120 cannabinoids that naturally occur at varying concentrations in Cannabis sativa. Initially, a one-class classification methodology was employed. 202 compounds (mostly pesticides, drugs, aromatic hydrocarbons, and cosmetic raw materials) with experimentally demonstrated ability to be secreted into human breast milk (coded as M/P(+)) were used as reference compounds. The key physicochemical properties of the reference compounds and cannabinoids were subjected to Principal Component Analysis. It was found that most cannabinoids fall within the chemical space of the reference compounds, so their physicochemical properties make them likely to be secreted into breast milk.
Similar results were obtained using novel, binary models based on 122 reference compounds that differ in their ability to enter breast milk (M/P(+) and M/P(-)). Discriminant analysis and artificial neural network models confirmed that most cannabinoids are likely to enter breast milk; these included several compounds whose transfer to the mother’s milk has not yet been studied.
Based on our analyses and the high consumption of phytocannabinoids by breastfeeding mothers, it may be concluded that offspring exposure via this route is a possible scenario.
