Microbial Analysis

About Microbial Analysis

Avoiding microbial contamination throughout the cannabis cultivation process is nearly impossible. Most fungal contaminants are harmless and exist ubiquitously in the environment. However, some present a health risk when consumed, even at low concentrations.

Aspergillus is a genus of fungi containing hundreds of distinct species. It thrives in nearly every climate and its spores are suspended in outdoor air year-round. Most species are non-toxic. However, Aspergillus fumigatus, Aspergillus flavus, Aspergillus niger, and Aspergillus terreus are all species native to North America known to cause allergic reactions in immunocompromised individuals. These species also produce potentially carcinogenic mycotoxins. Aspergillus species grow easily on cannabis flower and are a great concern for growers and consumers.


MRA has determined the criteria for acceptable microbial content in cannabis samples in colony forming units per gram (CFU/g). In accordance with MRA standards, samples exceeding the acceptable action limit in units of CFU/g are determined to have failed testing.

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