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

Feeding industrial hemp silage affected feed intake, milk yield, respiratory and heart rates, and behaviour of dairy cows. Transfer of cannabinoids from feed to milk was investigated with liquid chromatography-tandem mass spectrometry and toxicokinetic computer modelling, and potential exposure to consumers explored. 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 (Delta(9)-tetrahydrocannabinol (Delta(9)-THC), Delta(8)-THC, Delta(9)-tetrahydrocannabinolic acid, Delta(9)-tetrahydrocannabivarin, 11-OH-Delta(9)-THC, 11-nor-9-carboxy-Delta(9)-THC, cannabidiol, cannabinol and cannabidivarin) from animal feed to milk. For Delta(9)-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.

Automated summary

The transfer of cannabinoids from industrial hemp to milk was investigated in a feeding experiment with dairy cows. It was found that Δ(9)-THC had a transfer rate of 0.20%, exceeding the acute reference dose for humans in some scenarios of milk and dairy product consumption.