A moldy orange. Not necessarily the kind of stuff you’d find in cannabis. But still mold. Credit: Sandy Millar / Unsplash

Connecticut cannabis regulators have increased the acceptable amount of mold in tested product over the last year, leaving some advocates concerned about safety.

“It’s clear that the debate over industry best practices for cannabis microbial testing is far from over,” said medical cannabis patient Lou Rinaldi. “What is not up for debate, however, is that the August 2020 changes to the medical cannabis testing standards in Connecticut were made unethically and possibly even illegally.”

Last year, AltaSci Labs, one of Connecticut’s two cannabis testing labs requested that the state increase its threshold to 10^6 Colony Forming Units per gram, with the added stipulation that there be zero tolerance for Aspergillus mold. Basically, the state set a limit of 1,000,000 mold or fungal cells for every gram of flower. The state agreed with the new interpretation of the law, without issuing a formal rule about the change. 

The Association of Public Health Laboratories recommends that states adopt mold testing standards that cap the limit at 10^3 CFU/g.

Since the incarnation of its medical cannabis program, Connecticut has adopted a 10^4 threshold. Maine and Massachusetts, both of which have legal adult-use markets, follow the same threshold.

“There has been a focus on prohibiting specific yeast and mold organisms shown to be injurious to human health and safety, rather than placing a limit on all colony-forming units in general,” said Kaitlyn Krasselt, spokesperson for the Connecticut Department of Consumer Protection. “This protects public health and safety, while balancing the cost of cultivation and testing that is often passed down to the consumer.”

Although Aspergillus has been identified as a potential danger, especially to those who are immunocompromised, there is still uncertainty about the safety of other molds that could be present, such as Botrytis or Cladosporium.

“I wouldn’t be surprised if visibly moldy product begins clearing its way to shelves at 10^6 CFU/g. This isn’t like doubling the threshold, it’s increasing it by multiple orders of magnitude,” said Mike Esposito, lead microbiologist for MCR Labs in Framingham, Massachusetts.

Esposito explained that testing standards that look at the “total aerobic bacteria,” or “total yeast and mold” can be generally murky, because not all organisms that are detected bring an immediate risk of food poisoning or fecal-borne viruses. At the same time, setting a higher threshold for testing increases the likelihood of products harming users.

“Quality indicator tests mainly indicate the quality of production, so when we see very low counts of quality indicators on product we know that the grower is taking every step possible to make their product as safe and high quality as they can,” said microbiologist Esposito. “Excessively high counts on quality indicators could mean that working environments for individuals handling that material are sub-optimal, potentially leading to long-term issues like hypersensitivity pneumonitis or occasional opportunistic infections of the lungs or skin.”

“If I lived in a state where quality indicator action limits went up to 10^6, I would want to see COAs [Certificate of Analysis] for every product I bought telling me the actual count on the product, and I would try my best to avoid working at a facility where cannabis with 10^6 CFU/g was handled daily to protect my health over the long term.”

Finding the appropriate regulatory standard for cannabis is difficult, considering its Schedule I status, according to Krasselt. While there is no official standard, the United States Pharmacopeia does recommend that mold counts in cannabis products not exceed 10^4 CFU/g, with a zero tolerance for Salmonella and E. Coli.

“Contamination of cannabis inflorescence with pathogenic bacteria, yeast, and mold during cultivation, harvesting, drying, storage, and/or distribution is a serious risk, especially considering that cannabis may be consumed by at-risk patient populations such as those with compromised immune function,” said a report from the U.S. Pharmacopeia published last year in the Journal of Natural Products. 

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Zack cut his journalistic teeth covering high school sports in the south before spending a decade covering local government, politics and the courts in the Boston, Massachusetts area. He's previously written...