Harmful fungi that can contaminate hemp and marijuana plants are a potential threat to public health, according to a recent report by researchers from the U.S. and Canada.
“Hemp and cannabis are new crops, and we are in the early stages of understanding relationships with their pathogens,” said Kimberly Gwinn, a professor at the University of Tennessee (UT), one of the authors. “Several pathogens produce mycotoxins, compounds that negatively impact human health and are regulated in other crops.”
Historically, cannabis research has mostly focused on substance abuse and medical uses, but with the legalization of hemp and more relaxed laws for marijuana in many states, further study is needed to uncover any potential health risks in the cannabis crop system, the report suggests.
Even cannabis consumed for medical purposes, which presumably is under more strict safety controls, carries the risk of mycotoxins that might make some patients ill, the authors said in a press release from UT’s Institute of Agriculture.
Research gaps
In a comprehensive review, the report’s authors “summarize the current literature on mycotoxins in hemp and cannabis products, identify research gaps in potential mycotoxin contamination in hemp and cannabis (marijuana), and identify potential developments based on research in other crop systems.”
The report was published in the research journal Frontiers in Microbiology. In addition to Gwinn, professor of entomology and plant pathology at the UT agriculture institute, others contributing to the report were Maxwell Leung, assistant professor, and Ariell Stephens, graduate student, the School of Mathematical and Natural Sciences at Arizona State University; and Zamir Punja, professor of plant pathology/biotechnology at Simon Fraser University, Burnaby, British Columbia, Canada.
Standards lacking
“Although fungi and mycotoxins are common and well-studied contaminants in many agricultural crop species, they have been generally under-studied in cannabis and hemp,” the researchers said, noting that methodologies used to regulate food and pharmaceuticals have yet to become standard for the hemp and marijuana industries.
“The wide range of consumer uses of cannabis (marijuana) and hemp flowers, including for medical use by patients with susceptible conditions, makes it uniquely challenging to assess and manage human health risk of these contaminants,” according to the journal article.
The paper looks at Aspergillus, Penicillium, Fusarium, Mucor, and other fungi that can infect plants and produce mycotoxins. Environmental factors such as where the plants are grown, whether indoors or outdoors, and in soil or soilless media, may impact the kinds of contaminants and ensuing health risks, according to the report, which reviews regulations and research methods of such contaminants, and offers recommendations to produce safer products.
Highest risk: Smoking
Studies reviewed by the authors show some fungi may cause infection in lung and skin tissues in immunocompromised persons. Such infections were found to be most common when cannabis is smoked and less common in edible marijuana or hemp-derived products. The researchers also found cancer and transplant patients, and consumers with HIV and type 1 diabetes, may be particularly susceptible to infection. Workers who harvest hemp and marijuana could also be at risk, they said.
“A major hurdle faced by cannabis and hemp industries is addressing the disconnect between production-related issues and human safety issues,” the article states.
All case studies linking cannabis use and fungal infections, except one, involved patients who were immunocompromised, the researchers found. The authors urged such patients to use products that have been sterilized until better data are obtained.
The authors said one potential solution to reduce the risk of harm from fungi is to develop a two-tier system that distinguishes between medical and recreational products.
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