Tissue residue depletion of cannabinoids in cattle administered industrial hemp inflorescence

Despite interest in using industrial hemp (IH) in cattle feed, there are minimal safety data on tissues from exposed cattle. This study sought to describe cannabinoid tissue concentrations, estimate withdrawal times for cattle exposed to IH inflorescence, and generate human exposure estimates for Δ9-tetrahydrocannabinol and cannabidiol. Twenty male Holsteins received IH inflorescence orally at 4.2 mg/kg/d cannabidiolic acid for 14 d. Liver, kidney, muscle, and adipose were collected at 1, 2, 3, 5, and 8 days after IH administration and analyzed for cannabinoids using liquid chromatography mass spectrometry. Withdrawal intervals and target tissues were selected based on the slowest-depleting cannabinoid. ∆9-tetrahydrocannabinol was detected in liver, kidney, and adipose and cannabidiol in all tissues. Withdrawal intervals for liver, kidney, muscle, and adipose were 68, 21, 39, and 154 d, respectively. Adipose was selected as the target tissue and cannabidiol the marker residue. Exposure estimates generated using data from this study revealed that newborns exceeded the lowest published global toxicity threshold of 1 µg/kg Δ9-tetrahydrocannabinol. Additional work should determine safe levels of cannabinoid exposure in vulnerable populations (i.e. children and adolescents). Our results will inform future discussions regarding the inclusion of IH in cattle feed.