Potency trends of Delta(9)-THC and other cannabinoids in confiscated marijuana from 1980-1997

The analysis of 35,312 cannabis preparations confiscated in the USA over a period of 18 years for delta-9-tetrahydrocannabinol (Delta(9)-THC) and othe r major cannabinoids is reported. Samples were identified as cannabis, hash ish, or hash oil. Cannabis samples were further subdivided into marijuana ( loose material, kilobricks and buds), sinsemilla, Thai sticks and ditchweed . The data showed that more than 82% of all confiscated samples were in the marijuana category for every year except 1980 (61%) and 1981 (75%). The po tency (concentration of Delta(9)-THC) of marijuana samples rose from less t han 1.5% in 1980 to approximately: 3.3% in 1983 and 1984, then fluctuated a round 3% till 1992. Since 1992, the potency of confiscated marijuana sample s has continuously risen, going from 3.1% in 1992 to 4.2% in 1997. The aver age concentration of Delta(9)-THC in all cannabis samples showed a gradual rise from 3% in 1991 to 4.47% in 1997. Hashish and hash oil, on the other h and, showed no specific potency trends. Other major cannabinoids [cannabidi ol (CBD), cannabinol (CBN), and cannabichromene (CBC)] showed no significan t change in their concentration over the years.