Fungus present on cannabis can present a health concern due to the generation of metabolites known as mycotoxins that are toxic. These toxins are capable of showing negative health effects at concentrations in the part-per-billion (ppb) level. Of primary concern are a group of mycotoxins known as the aflatoxins. There are four forms of aflatoxins that are targeted in the analysis. These are aflatoxin G1, G2, B1, and B2. A fifth mycotoxin, ochratoxin A, is also monitored.
The threat posed by these toxins is greatest for patients with pulmonary complications as well as those who are immunocompromised. To date, little research has been done to study the effects of inhaling smoke from products contaminated with mold and fungus.
Testing for these toxins is mandated by Health Canada for medical marijuana, though it is applicable to all products that may contain fungal contamination and is meant for human consumption.