Derivation of a health-based guidance value for Δ8-tetrahydrocannabinol (Δ8-THC) and its occurrence in food.

The European Food Safety Authority (EFSA) was asked to deliver a scientific opinion on the derivation of a health-based guidance value (HBGV) for Δ8-tetrahydrocannabinol (Δ8-THC) in food with an assessment of the occurrence of Δ8-THC and the co-occurrence with Δ9-THC in hemp and hemp-derived products. Data from a clinical study were used to inform on the relative potency between Δ9-THC and Δ8-THC. The point estimate of the relative potency (ratio Δ9-THC/Δ8-THC) was in the range between 1 and 1.4, with 95% confidence between 0.97 and 1.63. Based on this range, the CONTAM Panel, using a conservative approach, set a relative potency factor of one for Δ8-THC. The CONTAM Panel had previously set an acute reference dose (ARfD) of 1 μg/kg body weight for Δ9-THC derived from adverse effects on human central nervous system (CNS). Given the similarity in the effects and the mode of action between Δ8-THC and Δ9-THC, the Panel considered that the established ARfD can be considered as a group ARfD for the sum of Δ8- and Δ9 THC. Regarding the occurrence of Δ8-THC, the majority of samples were left censored, in particular for hemp infusion leaves, hemp seed oil and hemp seeds (96%-99%). Highest detection rates and levels were found in the categories 'Sugar and similar, confectionery and water-based sweet desserts' and 'Products for non-standard diets, food imitates and food supplements'. Of 1145 samples, both substances were detected together in only 96 samples. If the two substances are produced naturally, a Δ8-THC to Δ9-THC ratio below 1 is expected; however, many of the samples, positive for Δ8-THC, were above this ratio indicating either addition of semi-synthetic Δ8-THC, formation during processing or enrichment of the natural Δ8-THC.