While researching my column for tomorrow, I noticed that the marijuana potency numbers in last week's press release on the subject from the Office of National Drug Control Policy don't match the numbers in the Potency Monitoring Project report (PDF) from which they supposedly were drawn. The press release says:
According to the latest data on marijuana samples analyzed to date, the average amount of THC in seized samples has reached a new high of 9.6 percent. This compares to an average of just under 4 percent reported in 1983 and represents more than a doubling in the potency of the drug since that time.
But these numbers, like the ones in an ONDCP graph labeled "Potency of Seized Marijuana, 1983-2007" (see below), are actually for imported marijuana, which in the samples tested by the PMP tends to be stronger than domestic marijuana. According to page 11 of the PMP report, the overall average THC level for marijuana seized last year was 8.1 percent, significantly lower than the number highlighted by the ONDCP. In the latest quarter for which data are available (mid-December to mid-March), the average was 7.9 percent, according to page 6 of the report.
This misrepresentation is not a huge deal, because the overall averages still show more than a doubling in THC content since 1983. But the fact that the ONDCP took the numbers out of the wrong column does not help its credibility, especially since this mistake had the effect of exaggerating the THC levels that federal drug warriors see as cause for alarm.
My first post on the ONDCP's announcement is here.
Addendum: At The Huffington Post, NORML's Paul Armentano notes that imported marijuana, which represented about two-thirds of the PMP samples last year, accounts for a minority of the U.S. market. He adds that "average THC in domestically grown marijuana—which comprises the bulk of the US market—is less than five percent, a figure that's remained unchanged for nearly a decade."