What are Mycotoxins?

A mycotoxin is a “mold-poison.” Mycotoxins are a secondary metabolite produced by fungi and some molds that readily colonize crops and can cause disease and death in animals, including humans. Some can cause cancer, some suppress the immune system, and others can attack the liver and kidneys. Mycotoxins have also been linked to tremors and nervous system disorders.The FDA has set regulations  for the maximum allowable amounts of mycotoxins that can be found in food and animal feed. The highest of which is 20 parts per billion for direct human exposure. To break that down, for every kilogram of product, no more than .02 milligrams can be from mycotoxins. Two of the primary types of mycotoxins that are associated with cannabis are aflatoxins and ochratoxins.

One of the main pushes for legalization of cannabis on a federal level is to ensure a standardized set of testing to eliminate harmful substances and organism that may be found during cultivation. States that have allowed medical and recreation use have done a great job policing themselves but in order ensure that the end user is getting a product that is safe from coast to coast federal oversight is required.



Aflatoxins are a type of mycotoxin produced by the Aspergillus parasiticus and Aspergillus flavus fungal species. If ingested they can suppress the immune system, mutate DNA, cause liver cancer and can cross the placenta to exert harmful effects into the fetus. There are five types of aflatoxins to be aware of: aflatoxin B1, B2, G1, G2 and M1. Aflatoxins are classified as a Level 1 carcinogen, Aflatoxin M1 is not a direct product of Aspergillus, but is an animal metabolite coming from animals that have consumed aflatoxin-contaminated feed.

When there is profound aflatoxin contamination in a crop, there is little, if anything, that can be done about it. Diluting a batch of contaminated material by mixing it with a non-contaminated batch of the same material is generally not allowed for consumable crops under the FDA regulations, although there have been extenuating circumstances in the past where exceptions have been made.

Other methods, such as chemical remediation with ammonia, are strictly prohibited for aflatoxin-contaminated crops.

Another property of aflatoxins that makes them so threatening is their molecular stability. These molecules maintain their molecular integrity in temperatures higher than 160 degrees Celsius, well above the melting point of known cannabinoids. If mycotoxins are present in cannabis during harvest, they have the potential to become concentrated above the FDA limits during processing into oils and extracts.



Ochratoxins also have a similar carcinogenic and mutagenic profile as aflatoxins. Ochratoxin A is produced by Penicillum verucosum as well as Aspergillus ochraceus. These fungal products are deemed a mutagen and carcinogenic due to their ability to break DNA strands and inhibit their repair mechanisms. There is also significant data linking exposure to Ochratoxin A to a serious and fatal kidney disease called Balkan Endemic Nephropathy.


The threat of aflatoxin and ochratoxin production is seemingly unavoidable when these species are present; but these biological processes can be minimized. Aspergillus is a fungus that grows in soil and numerous other places, under the right conditions. Aflatoxin contamination can occur anywhere from seed to harvest, as well as production and storage.

Like many microorganisms, Aspergillus favors environments with ample oxygen and moisture. Most pre-harvest strategies to prevent these mycotoxins involve chemical treatment, and are therefore not ideal for the cannabis industry. Rather, preventing aflatoxin production during harvest and storage are the most practical stages for mitigation. Studies have confirmed a positive correlation between aflatoxin production with increased water activity, or moisture percentage. Water activity is becoming a more common laboratory test; it can and should be used to determine how likely microbes may grow on a given crop.
Despite the lack of cannabis protocols and guidelines for reducing mycotoxin contamination, there are some basic practices that can be utilized from other agricultural facets that will help avoid the production of aflatoxins and ochratoxins.