The Mother of All Detection

A new analytical approach can detect trace levels of cannabis in breast milk

If knowledge on the long-term effects of medical cannabis is patchy, it is virtually nonexistent when it comes to a less obvious consumer – the breastfeeding baby. Cannabinoids are highly lipophilic, so combine easily with the fats present in breast milk; when breastfeeding mothers consume cannabis, infant exposure is difficult to avoid.

As legalization at the state level grows and as cannabis is increasingly used for medicinal reasons, there are growing calls to assess any adverse impact and raise public awareness. But current analytical methods struggle to detect cannabinoids at the extremely low concentrations found in breast milk, increasing the risk of false negatives – especially in cases of passive exposure.

To that end, researchers at the Center for Disease Control and Prevention (CDC) have developed a more sensitive approach to trace detection: alkaline saponification−solid-phase extraction (SPE) to separate cannabinoids from the milk fats, followed by isotope dilution UHPLC-MS/MS. They achieved detection levels of 13, 4 and 66 pg/mL for Δ⁹-tetrahydrocannabinol (THC), cannabidiol (CBD) and cannabinol (CBN), respectively – a significant increase in sensitivity compared with current methods.

Three key cannabinoids detected in the study.

In the published paper (1), the authors state that they expect the new method “to play a critical role in assessing infant exposure to cannabinoids through breastfeeding.” Although we are still a long way off fully understanding the impact of cannabis on nursing babies, being able to measure potential exposure takes scientists one step closer.


  1. B Wei et al., “Sensitive quantification of cannabinoids in milk by alkaline saponification-solid phase extraction combined with isotope dilution UPLC-MS/MS”, ACS Omega, 1, 1307–1313 (2016).