CU Boulder researcher warns of untested toxins in cannabis, calls for expanded safety measures – 9News
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BOULDER, Colo. — A University of Colorado Boulder researcher is raising new concerns about what may be lurking in legal cannabis.
Tess Eidem, Ph.D. said certain toxins tested for in food are not being screened in marijuana. She said she worries about the potential risk this could pose to consumers and workers.
“In the cannabis space… because there is no federal oversight, there’s kind of piecemeal state regulations that try to protect consumers, but really none of those regulations address a food safety approach,” said Eidem. “So, they basically allow anything to happen along your entire process as long as it passes compliance testing at the end.”
She said gaps in testing could leave a potentially dangerous blind spot for legal cannabis users. State regulators said they already test for certain mycotoxins and continue to review potential changes as research emerges.
Eidem is research associate and microbiologist at CU Boulder. She’s also former cannabis industry quality control specialist.
“In the cannabis industry you can grow infected plants, recover it, and treat it with some of these antimicrobial treatments which are remediation technologies. So, flower would fail [testing] because it was infected by a plant pathogen or it became spoiled after harvest and instead of identifying the root cause of those problems and addressing it there, many cannabis producers will just remediate and recover that contaminated product… that is concerning because it’s not really addressing the problem,” Eidem said.
Eidem said cannabis is already required to go through robust testing for things like heavy metals, pesticides, microbes, and some mycotoxins, but certain Fusarium mycotoxins, regulated in food, aren’t included. Eidem points to research, including a University of Arizona study, that found Fusarium mycotoxins in about 14% of cannabis samples tested, compared to less than 1% for the five mycotoxins currently required on state testing panels.
“One of those Fusarium mycotoxins is called Vomitoxin because when it’s eaten it makes people throw up,” said Eidem. “It has been found in Canadian cannabis at two times the level that is allowed in human food, and we’re also seeing an increased incidence in vomiting associated with cannabis use and so there’s a correlation there. We do not know if it’s causing some of this cyclical vomiting or cannabis hyperemesis syndrome that we’re seeing in cannabis users, but there’s enough evidence now to show that these mycotoxins produced by Fusarium could be a consumer safety risk.”
Eidem said in Colorado, contaminated or moldy cannabis that fails microbial testing can be remediated or treated, retested, and ultimately sold. She noted that consumers often have no way of knowing by sight whether the product was previously contaminated. A 2024 law forbids the state from labeling any cannabis products that are remediated, or previously failed testing. She said this approach focuses on passing a final test, instead of preventing contamination in the first place.
“Some of these microorganisms do survive irradiation and ozonation and other radio frequency, these remediation technologies, and we know that their mycotoxins can survive as well, so they are not erased away or eliminated off these cannabis products,” she said.
Eidem has presented scientific findings to regulators and advocated for expanding testing requirements, but said she faces pushback, including arguments that no established cannabis-specific testing methods exist.
“We test for them in all sorts of other crops, corn, wheat, rye, oats, soybeans,” she said. “Cannabis is not that much different than these other crops, so it would not take much time to really get some methods established.”
She said because of the lack of research in the cannabis space, the industry has been slow to adopt preventive safety measures used in food production.
“I’d like to see more funding for academic researchers to look at these mycotoxins, to see if it carries over into smoke, to see if it carries over an extraction into edibles and things like that,” said Eidem. “Understanding the risk to consumers is really important and part of these regulations is to protect consumers and patients, but if we aren’t looking at specific mycotoxins which we know can now be present on cannabis flower, then we’re really not protecting anybody.”
9NEWS also spoke with the Colorado Marijuana Enforcement Division (MED). A spokesperson for MED said while the literature available does not seem to point to a widespread issue of Fusarium mycotoxins in regulated marijuana that doesn’t mean they aren’t worried about it.
MED said they discussed at a Science and Policy meeting on Feb. 6 that “the determination of appropriate limits for testing is challenging, particularly when the toxicological profiles for the potential analytes and their route of administration is not available.”
MED went on to say they continue to explore the evolution and potential expansion of testing requirements. MED also has a team of investigators that routinely inspect licensed businesses.
