Potency Trends of Δ9-THC and Other Cannabinoids in Confiscated Marijuana from 1980–1997

Abstract

The analysis of 35,312 cannabis preparations confiscated in the USA over a period of 18 years for delta-9-tetrahydrocannabinol (⌬ 9-THC) and other major cannabinoids is reported. Samples were identified as cannabis, hashish, 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 potency (concentration of ⌬ 9-THC) of marijuana samples rose from less than 1.5% in 1980 to approximately 3.3% in 1983 and 1984, then fluctuated around 3% till 1992. Since 1992, the potency of confiscated marijuana samples has continuously risen, going from 3.1% in 1992 to 4.2% in 1997. The average concentration of ⌬ 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 hand, showed no specific potency trends. Other major cannabinoids [cannabidiol (CBD), cannabinol (CBN), and cannabichromene (CBC)] showed no significant change in their concentration over the years.

The Psychotomimetic Effects of Intravenous Delta-9-Tetrahydrocannabinol in Healthy Individuals: Implications for Psychosis

“…However, peak D-9-THC plasma concentrations with the 2.5 mg dose (82787.4 l ng/ dl) and 5 mg (119.27166.5 ng/dl) were within the range of levels achieved by ad libitum smoking of a standard NIDA cigarette (70-163 ng/ml) containing 1-2.5% THC (16-34 mg) (Heishman et al, 1990;Lindgren et al, 1981;Ohlsson et al, 1980a). Of note is that the D-9-THC content of cannabis has increased (ElSohly et al, 2000) probably as a result of the cloning of high yield cannabis plants and advanced cultivation techniques. The average cannabis joint from the 1960s and 1970s contained about 10 mg of THC.…”

Estimating the Time of Last Cannabis Use from Plasma Δ9-Tetrahydrocannabinol and 11-nor-9-Carboxy-Δ9-Tetrahydrocannabinol Concentrations

“…All had increases in heart rate and subjective drug effects. According to ElSohly et al (35 ), in 1997 the mean THC concentration in seized cannabis was 4.2%. Of course, cannabis can have a higher THC content.…”

The THC content of cannabis in Australia: evidence and implications

“…12 Data from the Marijuana Potency Monitoring Project have shown an increase in the THC content of 31,000 samples from 1.2% in 1980 to 4.2% in 1997 (see Figure 1). 10 The NZ Government has tested the THC content of cannabis samples over the past two decades. These have not shown any sizeable increase in average THC content which has remained within the range of 2.0% to 4%.…”