Mycotoxins

Molds that grow on damp plant material can secrete toxins into it. The ones regulated in cannabis are aflatoxins B1, B2, G1 and G2, produced by Aspergillus flavus and Aspergillus parasiticus, and ochratoxin A, produced by several Aspergillus and Penicillium species. They are stable molecules. Drying, heating and solvent extraction do not reliably destroy them, and extraction can concentrate them.

That stability is why mycotoxins get their own test. A microbial panel detects living or recently living organisms; a product can pass it after the mold has died or been killed by processing while the toxin remains. Testing uses liquid chromatography with tandem mass spectrometry, often after cleanup with immunoaffinity columns designed for aflatoxins and ochratoxin A (Cannabis Cannabinoid Res 2026). Results are reported in parts per billion.

Limits come from state cannabis rules, which set different thresholds and sometimes different analyte lists (Jameson 2022). Hemp outside those programs relies on the brand to choose a limit, and many borrow the state limits.

Control is upstream: harvest timing, rapid drying to a safe moisture level and storage below the water activity molds need. The certificate of analysis should list each toxin, its result, the limit and the detection limit.