Mold and fungi are found everywhere in the world. Due to their size and their spore’s mobility, fungi can spread throughout crops and food stores. When the conditions of humidity and temperature are favorable, the fungi can proliferate into colonies that can either destroy crops by consuming them or poison them with toxic secondary metabolites called mycotoxins. Just like some of the other potential agricultural contaminants (that is, pesticides and heavy metals), fungi, molds, and mycotoxins also must be of concern to the cannabis industry as a factor in product safety and quality. In this column, the world of fungi, mold, and mycotoxins is explored and discussed as they relate to the cannabis industry and the future of analytical testing.
The complexity and range of products produced by the cannabis industry makes it unique. The product range encompasses medicines, recreational agents, and food products. The industry has to worry not only about health effects of an inhalable product but also the effects of a medical preparation and food safety. The exposure risks of contamination from chemicals and microbials must be taken into consideration as the mode of ingestion of inhalation is used. The traditional industries of agriculture, food production, tobacco, and medicinal supplements all battle with contamination issues.
The traditional tobacco industry and now the vaping industry have been the object of scrutiny and testing, which has often showed significant levels of potentially dangerous contamination by chemicals and microbials (1). In the same vein, a large percentage of medical cannabis was found to be contaminated by some type of microbial organism in a study from UC Davis (2). In some cases, these microbial organisms were the cause of a patient’s death.
The food industry also struggles in the battle with contaminants. In the United States, it is estimated by the Centers for Disease Control and Prevention (CDC) that 48 million people get sick from foodborne illnesses and up to 3000 die from foodborne diseases (3). More than 250 agents are known to cause foodborne illness and are introduced through contamination, improper handling practices, and sanitation. These agents can be chemical, physical, or biological.
Biological contaminants are by far one of the greatest concerns for illness. Microbes are everywhere and can be beneficial or cause illness and death. The five types of microbes are bacteria, viruses, parasites, protozoa, and fungi. Fungi are a very diverse kingdom of organisms (single and multicellular) which once were considered plants. In the past, the study of fungi was a branch of botany. Now it is known that fungi are more closely related genetically to animals than plants. Fungi are nonphotosynthetic and must obtain nutrients from organic matter. Fungi that derive nutrients from decaying or dead matter are known as saprophytes; while a small percent of fungi derive nutrients from living organics and are called parasites. There are between 70,000–100,000 known species of fungi and possibly an estimated 3.8 million species in total (4).
The classification of Kingdom Fungi is constantly being debated with the influx of DNA data. Currently the kingdom contains seven phyla (Table I) (5), which span the different forms of fungal organisms from single-celled yeasts to multicellular mushrooms.
Many species of fungi produce biologically active compounds that are used in food production and medicine—where would the world be if we did not have yeast for bread or penicillin. But, there are also many toxic compounds produced by fungi.
“All Fungi Are Edible; Some Only Once” -Unknown
The classical thinking of toxicity from fungus is of the mushroom hunter out in the forest foraging for wild mushrooms. The typical mushrooms most of us think about are from the phylum Basidiomycota or club mushrooms. Toxic members of these phylums are infamous such as the Death Cap and Skull Cap. They produce secondary metabolites like amatatoxins, phallotoxins, and ergotamines that can easily be avoided by just not picking and eating those mushrooms. The more insidious toxic fungi are from the phylum Ascomycota, which include the molds, yeasts, mildew, and so on. These fast spreading and fast growing fungi are the plague of agriculture. These fungi produce the most common mycotoxins associated with food contamination.
Mycotoxins are organic compounds and secondary metabolites produced by fungus that are capable of causing illness and death. Secondary metabolites are not needed for the normal life cycle of the organism, in many cases the reason for their production is unknown (6). One species of fungi may produce different mycotoxins and some mycotoxins are produced by multiple types of fungi (see Table II). Most of the major mycotoxins of concern in human beings come from a few dozen species from the phylum Ascomycota or the sac fungi.
- J.L. Pauly and G. Paszkiewicz, J. Oncol. 2011, 1–13. https://doi.org/10.1155/2011/819129 (2011).
- G.R. Thompson, J.M. Tuscano, M. Dennis, A. Singapuri, S. Libertini, R. Gaudino, and A. Torres, et al., Clin. Microbiol. Infect. 23(4), 269–70, https://doi.org/10.1016/j.cmi.2016.12.001 (2017).
- CDC, n.d. “Estimates of Foodborne Illness in the United States” (blog). https://www.cdc.gov/foodborneburden/2011-foodborne-estimates.html.
- D.L. Hawksworth and R. Lücking, in The Fungal Kingdom, J. Heitman, B.J. Howlett, P.W. Crous, E.H. Stukenbrock, T.Y. James, and N.A.R. Gow, Eds. (American Society of Microbiology, Washington, D.C., 2017) pp. 79–95. https://doi.org/10.1128/microbiolspec.FUNK-0052-2016.
- D.S. Hibbett, M. Binder, J.F. Bischoff, M. Blackwell, P.F. Cannon, O.E. Eriksson, and S.Huhndorf, et al., Mycological Research 111(5), 509–47 (2007). https://doi.org/10.1016/j.mycres.2007.03.004.
- E.M. Fox and B.J. Howlett, Curr. Opin. Microbiol. 11(6), 481–87 (2008). https://doi.org/10.1016/j.mib.2008.10.007.
- P. Atkins, Cannabis Science and Technology 2(3), 22–27 (2019).
- R. Thomas, Cannabis Science and Technology 2(5), 22–30 (2019).
- “AZDHS | Public Health Licensing - Medical Marijuana.” n.d. Arizona Department of Health Services. Accessed November 14, 2019. http://www.azdhs.gov/licensing/medical-marijuana/index.php.
About the Columnist
Patricia Atkins is a Senior Applications Scientist with SPEX CertiPrep and a member of both the AOAC and ASTM committees for cannabis.
How to Cite this Article
P. Atkins, Cannabis Science and Technology 2(6), 20-23 (2019).