Marijuana products present unique testing hurdles

Image showing cannabis testing

Marijuana testing and quality control is no simple feat.

Consider the plant itself: Cannabis contains a super sticky, resin lipid that is harder to work with than coffee, tobacco and most other natural products, said David Vaillencourt, CEO of the GMP Collective consulting firm in Colorado.

“Separating out the cannabinoids to just look at pesticides is so much more complicated because we have to get rid of (the sticky resin) to separate that out and not lose the pesticides that we want to look for,” he explained.

Then there is the fact that flower at the top of a plant has higher THC levels than flower closer to the roots.

But there are ways to distinguish samples for better accuracy, Vaillencourt said.

“You can separate batches into top, middle and bottom thirds of the plant. And then you make sure you’re mixing it up and grabbing a representative sample, not cherry-picking. You have to have a method, a protocol to get the average and make sure it’s representative,” Vaillencourt explained. He noted that the ASTM International Committee D37 on Cannabis published a standard method for this procedure, ASTM DD334.

Table showing cannabis testing failure rates

Measured variety

Even under the best circumstances, it is impossible that all batches of flower, edibles, etc., test the same at different labs or that the milligrams of THC on a label will match what’s inside to the nearest thousandth. And that’s OK.

Other industries also allot for measurement variations, provided they’re reasonable, Vaillencourt noted. He said in pharmaceuticals, range tolerances of 2% and 5% are common. For example, an ibuprofen tablet labeled as having 400 milligrams might actually have 397 milligrams.

“We’ve identified what that reasonableness is,” Vaillencourt said. “Ranges are your best friend.”

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Many products, many locations

The sheer number of cannabis products and inputs makes implementing standards difficult.

In the product realm, there is not only flower but also a large variety of concentrates, edibles and beverages containing inputs that interact differently with cannabinoids, as well as a wide variety of topicals, tinctures, suppositories and other products.

“For every different product type, you need different (testing) methods,” Vaillencourt said. “For as many new and creative products that the industry is trying to come up with, we will likely need a unique method to some degree for each one.”

Kate Rimmer, a research chemist at the Maryland-based National Institute of Standards and Technology (NIST), noted that it is common for states to have different standards for different products.

“For example, different states have different regulations about the pesticides that can be in foods. We try to provide the tools that encompass all of the regulations that we can,” Rimmer said.

Change approach

While harmonizing standards will advance quality control, it will also be important for the industry to rethink how it approaches testing more generally, Vaillencourt said.

“Part of the issue is that we take this ass-backwards approach. … In the food or pharmaceutical industry, we say: What are you putting in your product?” Vaillencourt said. “Then we test for it.”

For that approach to effectively function, Vaillencourt said, regulators would need to require that cannabis businesses maintain a list of all ingredients and raw materials—as well as their origins.

Vaillencourt said such a tracking system might have prevented the 2019 vape crisis.

“No state was saying, ‘Test for vitamin E acetate.’ That wasn’t a risk factor that anybody identified. So it wasn’t that people were hiding things. We just didn’t think to test for it,” Vaillencourt explained. “That’s how we ended up with a big crisis.”