Microbial Contamination of Cannabis-Infused Foods

Cannabis-infused food products usually look just like any other foodstuff. In many cases, an infused product may taste quite similar to its non-infused counterpart. Yet on a food safety level, the two stand distinctly apart. Though cannabis flower contains a number of potentially active compounds, such as flavonoids and aromatic terpenes, the term “cannabis” in cannabis-infused product refers primarily to the addition of active cannabinoids—chiefly, tetrahydrocannabinol and/or cannabidiol, but also cannabigerol and cannabinol. Such cannabinoids are usually received from cannabis extractors in the form of cannabinoid distillate. Due to the heat and chemical extremes required to extract cannabinoids to distillate, this is good news for those worried about the potential for microbial pathogens endemic to the cannabis plant to contaminate products downstream.

Zamir Punja, PhD, a professor of plant biotechnology at Simon Fraser University in Burnaby, B.C., Canada, was lead author of a 2019 study that cataloged pathogens and molds affecting the cannabis plant. He notes that most of the seven or so pathogens affecting cannabis flower buds would not survive any solvent extraction, or liquid carbon dioxide, or temperatures higher than 60^oC—the conditions under which cannabinoids are usually extracted.

“I would consider these methods to have eliminated living microbes,” Dr. Punja tells Food Quality & Safety. “What we don’t yet know is what would happen if a contaminated bud has [fungal] growth on it and the microbe produces a toxin. Some of these toxins can survive solvent extraction and are heat stable. So, they may survive through the extraction process, and possibly be concentrated. The majority of the mold should be killed by extraction, but it remains to be seen whether toxins that may be produced by the microbes growing on moldy product can still be detected in extracts.”

Kevin McKernan, the chief science officer and founder of Beverly, Mass.-based cannabis biotechnology firm Medicinal Genomics, concurs, noting that CO₂ or ethanol extraction processes sterilize the cannabis flower, but may also enrich mycotoxins and pesticides in the process. “Not all microbial contaminants are flower derived, and regulators are still looking to ensure the infused products have not been contaminated downstream of the extraction process,” he says.

Oversight

What kind of a threat do such processed mycotoxins pose for consumers? Charles T. Deibel, president of food safety testing firm Deibel Laboratories, acknowledges Dr. Punja’s and McKernan’s concerns, but he’s not certain how much we should worry about them. “Aspergillus produces an extremely heat-stable toxin aflatoxin,” Deibel says. “[Aflatoxin] is an extremely stable toxin structure, and it can absolutely survive some of the processing to make distillate, but it’s rare. You’re just looking at a numbers game. Bacteria are a hell of a lot more prevalent in recalls and [incidences of] foodborne [illness] than some of these oddball toxins like aflatoxin.”

Not just bacteria, says Lori Glauser, co-founder and interim CEO of Nevada cannabis testing firm EVIO Labs. Before infused foods and beverages go to market, producers are also testing for a variety of pathogens. “We test the final product, not just the cannabis ingredient,” Glauser says. “When testing for yeast, mold, E. coli, Salmonella, and mycotoxins in infused products, it is more likely that the pathogen is introduced from the food product itself rather than the cannabis component.”

Even the best company with all the right programs [will] still find a pathogen maybe once every five years—10 years if they’re lucky. But they find it. The pathogen is always waiting at your door.—Charles T. Deibel

It’s the food product, not the cannabis, that makes infused products so complicated, because, while infused foods come in an increasingly wide variety of shapes, flavors, and permutations, infused products are not subject to FDA oversight. “As soon as you put THC in a food product, the FDA says, ‘Not my jurisdiction,’” says Deibel.