Transfer of cannabinoids into the milk of dairy cows fed with industrial hemp could lead to Δ⁹-THC exposure that exceeds acute reference dose

The industrial hemp sector is growing and, in recent years, has launched many novel hemp-derived products, including animal feed. It is, however, unclear to what extent individual cannabinoids from industrial hemp transfer from the feed into products of animal origin and whether they pose a risk for the consumer. Here we present the results of a feeding experiment with industrial hemp silage in dairy cows. Hemp feeding included changes in feed intake, milk yield, respiratory and heart rates, and behaviour. We combined liquid chromatography-tandem mass spectrometry-based analyses and toxicokinetic computer modelling to estimate the transfer of several cannabinoids (Δ⁹-tetrahydrocannabinol (Δ⁹-THC), Δ⁸-THC, Δ⁹-tetrahydrocannabinolic acid, Δ⁹-tetrahydrocannabivarin, 11-OH-Δ⁹-THC, 11-nor-9-carboxy-Δ⁹-THC, cannabidiol, cannabinol and cannabidivarin) from animal feed to milk. For Δ⁹-THC, which has a feed-to-milk transfer rate of 0.20% ± 0.03%, the acute reference dose for humans was exceeded in several consumer groups in exposure scenarios for milk and dairy product consumption when using industrial hemp to feed dairy cows.

Bettina Wagner, Pietro Gerletti, Peter Fürst, Oliver Keuth, Thorsten Bernsmann, Annett Martin, Bernd Schäfer, Jorge Numata, Marc C. Lorenzen, Robert Pieper