A mycotoxin is a highly toxic compound produced by fungus or mold. Mycotoxins are dangerous to humans, animals, and plants. Mold, and any toxin produced, can infest cannabis before harvest or while it's being stored or transported. It can also grow on edibles directly. Mycotoxins are a byproduct of mold growth that can remain toxic and unseen even after cannabis processing.
Jurisdictions with regulated medical or adult-use cannabis tend to require analytical laboratory testing of the two major mycotoxins found in cannabis, aflatoxins, and ochratoxins. Aflatoxins, normally found in soil, are some of the most harmful. Ochratoxins, produced by the molds Penicillium species and Aspergillus, are common contaminants in the food chain. Laboratories report the quantity of mycotoxins detected in micrograms per kilograms (µg/kg).
Mycotoxin exposure doesn't usually lead to death but rather damages internal organs and the immune system when cannabis consumers are exposed to regular, small doses over time. This can be especially harmful to medical marijuana patients with organ damage, kidney or liver cancer, or weakened immune systems.