Median CBD Potency Decreasing In Confiscated Marijuana Samples, Study Says

Santa Monica, CA: Detectable levels of the cannabinoid CBD (cannabidiol) are declining, according to a review of over 5,000 marijuana samples seized by law enforcement in California. The review appears on the website of the journal Drug and Alcohol Dependence.

Investigators at the RAND Corporation in Santa Monica assessed changes in the median THC and CBD levels of cannabis samples seized in California between the years 1996 and 2008. Researchers reported that median THC levels rose during this time period while median CBD levels fell.

“[M]edian THC potency has increased from 4.56 percent in 1996 to 11.75 percent in 2008,” authors reported. “The increase in THC was far more dramatic in non-border areas (from 4.18 percent in 1996 to 13.95 percent in 2008) than in border areas (4.52 percent in 1996 to 6.84 percent in 2008). … [W]e see the opposite trend for CBD. … The median level of CBD dropped from 0.24 percent in 1996 to 0.08 percent in 2008.”

Authors of the paper speculated that the falling potency of CBD in seized samples was because “growers are making greater use of plant strains that favor THC production over CBD production.”

Cannabidiol is a nonpsychotropic cannabinoid that is believed to temper the psychoactive effects of THC. In preclinical trials, the compound has demonstrated the ability to both treat symptoms and modify the course of various diseases. A recent review published in the journal Trends in Pharmacological Sciences reported that CBD possesses over a dozen separate therapeutic properties – including anti-cancer properties, anti-diabetic properties, anti-epileptic properties, and anti-bacterial properties.

In recent years, a select number of growers have begun breeding ‘CBD-rich’ strains of cannabis (defined as four percent CBD or higher) specifically for the medical marijuana market. Information on these strains, their CBD content, and their availability to the public is available online at the website:

For more information, please contact either Paul Armentano, NORML Deputy Director, at:, or Dale Gieringer, California NORML Coordinator, at: (415) 453-5858. Full text of the study, “Heterogeneity in the composition of marijuana seized in California,” will appear in the journal Drug and Alcohol Dependence.