CYP1A1 and cannabis dependence: Indeed, pharmacokinetic studies showed that after sub-chronic Δ9-THC treatment of rats, plasma concentrations of Δ9-THC were in the 2-4 ng/mL range [35], which is close to those plasma concentrations observed in humans cannabis abuser [36] and about three orders of magnitude lower than the Δ9-THC concentrations needed to induce Cyp1a1 in vitro [17].