Medical Cannabis Potency Testing Project

Dale Gieringer, Ph.D.

California NORML, 2215-R Market St. Suite 278

San Francisco CA 94114 tel: (415) 563-5858

E-mail: canorml@igc.apc.org Given the rapidly growing use of medical cannabis for a wide variety of indications and the manifold different underground sources currently supplying patients, there is a natural interest in investigating the potency, purity, and chemical content of the available supplies of medical cannabis. While the availability of medical cannabis has increased in the wake of the passage of California's Proposition 215 and other state medical marijuana initiatives, scientific research on its content remains frustrated by the continued federal ban on medical cannabis research. In an effort to cast light in this obscure area, a research project was undertaken by a group of us, including researchers, growers, and medical cannabis buyers' clubs, with support from California NORML and MAPS, to analyze samples of medical cannabis from various patients' cooperatives and providers around the country. This effort proved to be a lesson in the difficulties and uncertainties of cannabis research in a society where freedom of pharmacological research has been stifled by an effectively totalitarian drug bureaucracy. From the outset, our project was frustrated by a lack of access to qualified research labs with expertise in analysis of cannabis. The leading research lab in the country declined to do business with us for fear of compromising government contracts, while the other likely candidates were all foreign and thus not legally accessible to us because of DEA regulations. In the end, we were fortunate to obtain the services of a laboratory that had the requisite DEA license and equipment (a gas chromatograph mass spectrometer, or GCMS), but no prior experience in cannabis analysisin fact, its primary business was drug urinalysis! The analysis of our samples was accordingly a learning process for both the lab and ourselves. Our original aim had been to obtain a broad-spectrum quantitative analysis of as many of the 60-plus naturally occurring cannabinoids as possible, in the hope of detecting differences that might produce differing therapeutic effects among the samples. To our disappointment, however, our lab could obtain laboratory standards only for the three most common cannabinoids, delta-9-THC, cannabidiol (CBD), and cannabinol (CBN). A total of 47 different samples of medical cannabis were submitted by over a half dozen different providers and patients' cooperatives ranging from California to the East Coast. Included were 42 samples of sinsemilla bud, three samples of hashish or resin; one liquid sample of a milk-based cannabis drink ("Mother's Milk"), and one capsule of an oral whole leaf preparation. Upon analysis by GCMS, the potency of the 42 sinsemilla samples was determined to range from 10.2% to 31.6% THC, with a mean of 19.4%. These results were surprisingly high, given that the average potency of marijuana in the U.S. has been typically estimated at around 3% to 4% by NIDA, with higher grade sinsemilla ranging towards 10% - 15%. The highest potency recorded came from a sample of hashish, which registered 68.6%. Yet even a sample of Mexican commercial grade registered a surprisingly high 11%, twice what we had expected. All of this cast a troubling shadow of doubt on our test results, although it appeared likely that we were dealing with highly potent varieties. In contrast, the CBD levels observed were surprisingly low. Only four of the sinsemilla samples had more than 0.3% CBD, and 35 of them had only trace amounts (<0.1%). However, one sample had an astoundingly high CBD content of 28.0% (plus 11.6% THC). Another registered 5.6% CBD and 13.4% THC. Aside from these two anomalies, the CBD results were frankly disappointing, as we had hoped to discover significant variations in the content of the samples, with accompanying variations in medical activity. Because CBD is suspected to have peculiar efficacy for control of muscle spasms and for damping anxiety and "panic reactions" caused by THC, we had hypothesized that certain patients would tend to prefer high-CBD varieties. In fact, however, it appears that few patients are ever exposed to high-CBD cannabis. Unfortunately, we were unable to procure additional specimens of the high-CBD varieties for further testing. As for CBN, the majority of samples showed only trace amounts. The highest level detected was 1.4%, and only one other sample tested above 1%. CBN is a breakdown product of THC, so high CBN levels are expected in old, degraded samples. This was confirmed by the fact that one of the samples above 1% CBN was known to be a year old. The prevalence of low CBN in the samples was evidence that most available medical cannabis tends to be fresh and well-preserved. Otherwise, these results were of limited interest, as there are few if any known medical effects of CBN. Another disappointing surprise was the failure to detect more than trace levels of THC or CBD in the liquid "Mother's Milk" sample. Upon further investigation, the lab determined that this was because it is impossible to extract cannabinoids from fat-based liquids using standard methanol extraction techniques. Consulting with other researchers, we found that there is no known method for isolating THC from fat-based liquids. Later, we located a lab that claimed to have developed a secret, proprietary method for extracting cannabinoids from fat. With considerable difficulty, we arranged to have the lab test the Mother's Milk. To our disappointment, however, once again only trace amounts of THC and CBD were detected. Just to make sure, one of us swallowed a sample of the Mother's Milk (which by now had spent several months in the freezer) and found it to be delightfully potent. Evidently, the lab's technique had failed. It appears that further advances in testing technology will be needed in order to properly analyze fat-based oral cannabis products such as Mother's milk, bhang, ghee, and possibly baked goods such as brownies. Table: THC and CBD Test Results (Round 1 vs. Rounds 2 and 3)