The charts, above, show all the test results for cannabis flower in Massachusetts for the years 2019 and 2022. The x-axis is "Max THC," and tells you the total maximum THC yield per mass of flower. The y-axis is number of test results, and tells you how many times flower was reported to contain a particular level of THC in that year. Notice how the reported levels of THC increased... in 2018, most flower was labelled under 20% Max THC, but in 2022 most was labelled over 20%
But did the potency of flower really change? Maybe a little.
Most of the cannabis flower tested each year is produced by the same big companies (so-called MSOs), using the same growing methods. For the years 2018-2020, the potency of flower barely budged.
In 2021, Massachusetts got a couple of new testing labs that are owned by big investors. The levels of THC reported in cannabis flower began to rise. We broke down the data into several groups, based upon the wording of a comment in each entry. The grouping by comments breaks up the data into tests reported by a few different labs, or groups of labs. This allowed us to show that a small subset of labs produces higher average levels of Max THC than the rest.
Analysis of these aggregated data is a powerful tool! The Cannabis Control Commission of Massachusetts (CCC) lacks the skill and willingness to do this work. By monitoring these data, the Institute of Cannabis Science pressures the markets for cannabis to become more honest.
We bought cannabis and had it tested at three different labs.
Even though the three labs have differences in their methods, they gave results for potency that were highly consistent with each other - but different from the label!
The blue column, above, shows the Max THC reported on the labels for 15 strains of flower. The green column to its right shows the average of values of Max THC measured by our three labs. Notice that we ALWAYS find less THC than the label says!
There is an additional trick some dispensaries use to advertise really high levels of THC. Some list "Total THC" on their website, a number they make by adding the weight% of THC to the weight% of THCA, without correcting for the loss of mass when THCA is converted to THC by decarboxylation. These numbers are in red boxes in the table above.
That's how a dispensary can advertise flower at 35.2% THC when it only yields 24.8% THC (third row in the table above).
Some dispensaries use the weight% of THCA, the precursor to the active THC, from the label when they note the level of THC on their website. These are the values in yellow boxes in the "advertised" column, above.
Off-the-shelf testing measures the honesty of the market. The first step to making cannabis markets safe is measuring what buyers receive.