A Comprehensive Review of Cannabis Potency in the USA in the Last Decade

This report examines the concentration of seven major cannabinoids including Δ⁹-THC and CBD in illicit herbal cannabis products seized by the Drug enforcement Administration (DEA) over the last ten years in the USA. Cannabis Samples received from DEA reginal laboratories are analyzed by a validated GC/FID method and the results given in the report. A total of 14234 samples of herbal cannabis have been analyzed over the last ten years (between January 1, 2009 and December 31, 2019). The number of samples received over the last five to six years has decreased dramatically due to the legalization of marijuana either for medical or for recreational purposes in many US states. The results showed that the mean Δ⁹-THC concentration has increased over the last 10 years, from 9.75% in 2009 to 14.88% in 2018 and 13.88% in 2019. The mean Δ⁹-THC:CBD ratio rose substantially from 24.81 in 2009 to 103.48 in 2017. A decrease in THC:CBD ratio was recorded in the last two years, 54.39 in 2018 and 24.58 in 2019, indicating the trend in the production of more high CBD containing products. Our results show that an overall increase in potency of illicit cannabis going from approximately 10% in 2009 to approximately 14% in 2019. These results are in agreement with other potency monitoring programs in several European countries. There appears to be a recent trend of the inclusion of higher CBD levels containing chemovars in illicit cannabis.