Most cannabis labs are skeptics of THC content above 30%
By Aaron Stancik
A recent article from the April issue of Marijuana Venture highlighted what could have been, at the time, the highest potency marijuana ever reported on the planet. This weed was reported at an astronomical 41.7% THC-A. This converts to 36.6% THC, plus around 1% native THC in the plant, for a total of 38% THC. That is a radical 10% higher than award-winning Dutch cannabis strains.
The producer and author of the 41.7% story did his due diligence trying to validate the results of his lot’s reported potency. He also put together a well-written article. I can tell he had good intentions, was knowledgeable and obviously an expert grower. My response is not an attack on the authenticity of his story, but a critique of quality assurance in the Washington cannabis industry.
As scientific director of CannaSafe Analytics, I have been testing in Washington’s recreational cannabis industry since its inception. We have seen hundreds of cannabis flowers, some of which are definitely world class. After hundreds of potency measurements, the highest we have seen is 29.2% total THC. We have consistently seen the same high-THC producing strains pushing this upper limit.
In the 41.7% article, the author admitted initial shock at this high result. The editor expressed a healthy dose of skepticism too, which is a sentiment echoed by many in the cannabis science community. Heck, everybody admitted skepticism, including the manager of the lab that thrice reported it. According to the Cannabis Inflorescence Monograph, published by the American Herbal Pharmacopoeia, cannabis has an upper range around 25% THC. Ed Rosenthal in his book, “The Marijuana Grower’s Handbook,” cites 15-20% THC as constituting high-grade cannabis.
From discussions with several of my colleagues, I think most of us agree on where the actual upper limit of THC peaks.
Further, an opinion doesn’t validate a scientific result. Unfortunately, to try and validate the 41% result, the same lab retested the sample. If there is a deficiency in a lab’s methodology or quality systems, that mistake will be made systematically. The best way to validate a test result is have multiple labs perform the test. That is the concept behind proficiency testing.
A proficiency test is when a standard solution of known concentration is sent to all certified analytical labs operating in an industry. The true value of a proficiency test is the average of all results from each lab. Each lab is graded by how close they get to the average. In other words, no single lab is considered right. It is the average that best represents the actual value.
Given the current backdrop of outlandish potency inflation in the Eastern Washington market, producers who think they may have a world record would be well-advised to validate the results with a second opinion. There are 14 certified testing labs in Washington State, and some of them have built a reputation on doing good science. I have worked with members of good labs in our inter-lab working group. The Liquor Control Board has a list of the participating labs, and we are all actively involved in bringing standardization to cannabis testing.
THC-A content is a good measure of cannabis potency as it converts directly to the psychoactive compound THC. THC-A is the predominant cannabinoid in drug-type cannabis. In fact, very little neutral THC is present in the plant and it’s usually only around 1%. So, a grower can look directly at THC-A to gauge potency.
Now let’s look at the rational the author used to try to validate his world record potency. The author cited an Australian publication from PLOS ONE. In the Australian study of 218 samples, the average THC-A content was 15.02%. The study showed a few points that were likely statistical outliers above 40% THC-A. Data points significantly above average, and at the edge of a data set are generally considered outliers.
In other words, the validity of statistical outliers should be highly suspect. Now consider that the author’s 41.7% THC-A sample was 2% higher than the most outlying point in the Australian data. That definitely warrants a second professional opinion. Most dedicated cannabis labs would notice there is a problem if they saw a number like that.
In the article, the author makes it sound like cannabis has never been tested at the currently prescribed levels. To the contrary, cannabis has been tested for decades by state crime labs and forensic labs. Tens of thousands of cannabis samples, confiscated by law enforcement, have been analyzed annually. This is true worldwide, as cannabis is internationally prohibited. It has also been regularly tested by the Canadian and Dutch cannabis industries, and in the Colorado and California markets.
My friends at The Werc Shop, a well-respected cannabis lab, have tested thousands of cannabis flowers and never seen one over 30% total THC. Nowhere on the planet does cannabis test out at the inflated levels being reported in Washington State.
The author mentioned that the lab in question retested the sample three times with exactly the same result. As a Ph.D. chemist with years of analytical chemistry experience, I have to disagree. No analysis with even the most expert analyst and state-of-the-science instrumentation will ever give the exact same results. There is always a spread. It is called variance. The three results should be averaged to give the most accurate result. Three tests will give three numbers, which wasn’t mentioned in the article. Cannabis is especially varied and individual plants can have a THC gradient of about 15% from the top to bottom flowers. Even two choice buds from the same plant can vary by a few percent.
Now let’s put a THC-A content of 40% into perspective. Recently, I tested half a dozen kief samples. The average THC-A concentration of the kief samples was 42.7% THC-A, and kief is processed, concentrated resin glands from cannabis flower. At 40% THC-A, nearly half of the plant would be a single chemical compound. There would literally be no plant material left. A 40% THC-A test result belongs on a concentrate or extract.
While potency garners a great deal of attention, microbial contamination is even more crucial. CannaSafe and another lab recently tested product that was being sold in a retail store. The testing was performed independently and neither lab was aware of each other’s findings until after the results were reported. In science jargon, it was a blind study.
Both labs found that its potency was less than half the reported number on the label, and it failed for yeast and mold contamination. This is the true problem. It’s not the inflated THC values that are of most concern. No one will die from too much THC. Microbial contamination on the other hand can be quite toxic. That is a public safety and consumer health concern that the Liquor Control Board needs to address immediately. Someone is going to get sick on moldy weed, and lawsuits will start brewing in the Washington industry.
At a recent lab meeting in Olympia, I recommended a solution to the Liquor Control Board that would solve the problem of potency inflation in the industry. The agency can require BioTrackTHC, through the state’s traceability system, to flag all data reported above 35% THC-A, which corresponds to 30% THC. The agency could then identify which producers and testing labs were turning out
This would give dishonest parties an incentive to play by the rules.
For our part, CannaSafe Analytics issues this challenge to the cannabis industry in Washington State: If you discover any cannabis flower over 40% THC-A, CannaSafe will retest it for free and report the results to the Liquor Control Board. If you are in Western Washington, we will arrange for a reputable lab from our inter-lab working group to retest the sample.
As an industry, let’s stop the insanity and start the process of reporting potency accurately. The numbers don’t have to be in the stratosphere for consumers to buy it. Consumers just need to be educated on what constitutes great cannabis. Terpenes, cannabinoids and water activity all affect cannabis quality, aesthetics and flavor, not just THC.