Saji George PhD Associate Professor & Chair, Department of Food Science and Agricultural Chemistry Canada Research Chair in Sustainable Nanotechnology for Food and Agriculture Faculty of Agricultural and Environmental Sciences, McGill University Quebec, Canada

02 Feb Cannabis Products Not Necessarily Free of Toxigenic Fungi and Pathogens

Posted at 21:14h in Addiction, Author Interviews, Cannabis by

MedicalResearch.com Interview with:

Saji George PhDAssociate Professor & Chair, Department of Food Science and Agricultural Chemistry Canada Research Chair in Sustainable Nanotechnology for Food and Agriculture Faculty of Agricultural and Environmental Sciences, McGill University Quebec, Canada

Dr. Saji George

Saji George PhD
Associate Professor & Chair, Department of Food Science and Agricultural Chemistry
Canada Research Chair in Sustainable Nanotechnology for Food and Agriculture
Faculty of Agricultural and Environmental Sciences,
McGill University Quebec, Canada

MedicalResearch.com: What is the background for this study?

Response: Cannabis plants are highly susceptible to microbial contamination, particularly by fungi producing harmful mycotoxins. Infection of plants by fungal pathogens could result in the contamination of cannabis products with mycotoxins that pose serious health risks, especially for immunocompromised patients who use cannabis for medical purposes. Currently industry employ decontamination methods such as gamma irradiation to clean up cannabis products likely to harbor fungi and their metabolites. However, their effectiveness in fully eliminating toxigenic fungi and associated mycotoxins remains unclear.

Our studies aimed to evaluate the persistence of fungi and mycotoxins in dried cannabis buds following gamma irradiation, using a combination of culture-based, molecular, and immunological techniques. These studies revealed that complete sterilization of cannabis buds once contaminated with mycotoxin is extremely difficult and highlighted the importance of early interventions in preventing toxigenic fungi during cultivation.


MedicalResearch.com: What are the main findings?

Main Findings:

  • Gamma irradiation significantly reduced fungal and bacterial loads, eliminating culturable bacteria; however, complete sterilization was not achieved.
  • Viable spores of toxigenic fungal genera such as Aspergillus, Penicillium, and Fusariumpersisted post-irradiation.
  • ITS sequencing and next-generation sequencing (NGS) revealed the presence of both culturable and non-culturable mycotoxigenic fungi in irradiated and non-irradiated samples.
  • PCR/qPCR detected biosynthetic genes for aflatoxins, trichothecenes, ochratoxins, and deoxynivalenol (DON) across all samples, with gene copy numbers remaining largely stable post-irradiation, indicating DNA damage without full degradation.
  • ELISA confirmed the presence of aflatoxins, ochratoxin, DON, and T2 toxins in irradiated and licensed producer samples, albeit at variable concentrations.
  • Licensed producer samples generally had lower microbial loads and gene abundance, but residual DNA and toxins 

 

MedicalResearch.com: What should readers take away from your report?

  • Cannabis products hitting the market are not necessarily free of toxigenic fungi and their metabolites. Consumers, especially those who are immune compromised, should be aware about the health risks associated with fungi and their metabolites.
  • Regulatory safety assessments of cannabis products should combine culture-based, molecular, and immunological techniques.
  • Stricter quality control and quality assurance programs should be implemented throughout the supply chain to minimize the risk of mycotoxin exposure, particularly in medical cannabis.

 

MedicalResearch.com: What recommendations do you have for future research as a results of this study?

Investigate alternative or complementary decontamination methods that more effectively remove both viable fungi and their mycotoxins.

  • Develop standardized, sensitive detection protocols for routine monitoring of toxigenic fungi and mycotoxins in cannabis products.
  • Study the long-term stability and health impacts of residual mycotoxins in cannabis under various storage and processing conditions.
  • Explore the potential for breeding or cultivating cannabis varieties with reduced susceptibility to fungal contamination.
  • Test the applicability of biocontrol agents in mitigating fungal growth and activity at the cultivation phase

 

Citation: Rani M, Kaddoura MJ, Samsatly J, Chamberland G, Jabaji S, George S. Detection of Mycotoxigenic Fungi and Residual Mycotoxins in Cannabis Buds Following Gamma Irradiation. Toxins. 2025; 17(11):528. https://doi.org/10.3390/toxins17110528

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Last Updated on February 2, 2026 by Marie Benz MD FAAD

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