Potency trends of Δ9-THC and other cannabinoids in confiscated cannabis preparations from 1993 to 2008.
Level 4 - case-series / case-control
Serial cross-sectional analysis of seized forensic samples (graded by design analogy for non-clinical surveillance).
PubMed 20487147 · doi:10.1111/j.1556-4029.2010.01441.x
What was done
Gas chromatography-flame ionization detection (GC-FID) was used to measure cannabinoid potency in 46,211 cannabis preparation samples seized in the United States between 1993 and 2008 under the National Institute on Drug Abuse (NIDA) Potency Monitoring program.
What was found
The mean Δ9-tetrahydrocannabinol (Δ9-THC) content across all confiscated cannabis preparations increased from 3.4% in 1993 to 8.8% in 2008. Mean yearly hashish potency varied from 2.5% to 9.2% during 1993–2003 and from 12.0% to 29.3% during 2004–2008. Hash oil potency averaged 16.8 ± 16.3% over the study period. The rise in overall preparation potency was primarily driven by nondomestic relative to domestic samples.
Why it matters
This study documents a more than twofold increase in the average THC concentration of illicit cannabis seized across the United States over a 15-year surveillance period.
Limits
Samples were derived entirely from law enforcement seizures, which may reflect policing priorities and interdiction methods rather than true market-wide consumption. The abstract does not provide exact sample breakdowns between domestic and nondomestic sources, nor does it detail storage conditions or potential cannabinoid degradation prior to analysis.
Cited by
- supports In the 1980s and 1990s, average cannabis THC content was approximately 3% to 5%.