Microbial panel

Hemp is a plant grown outdoors, dried in barns and handled by people, so it carries microorganisms. Most are harmless. The panel looks for the ones that are not and for total loads that signal poor drying, storage or sanitation.

Common targets are total aerobic bacteria, total yeast and mold, bile-tolerant gram-negative bacteria, Escherichia coli, Salmonella and several Aspergillus species. Which ones a lab tests, and the limits it applies, follow state rules that vary considerably (Jameson 2022). Hemp sold outside a state cannabis program may have no required panel.

Two methods are used. Culture plating grows organisms on media and counts colonies, which takes days. Quantitative PCR detects microbial DNA within hours but can count dead cells. A 2026 review of cannabis contaminant methods notes that labs are still working toward consistent validated approaches across product types (Cannabis Cannabinoid Res 2026).

Risk follows format. Flower and raw biomass carry the most organisms. Extraction with solvents or CO2 and the heat of distillation remove most of them, so isolate and distillate products rarely fail. Gummies and other water-containing edibles can support growth after manufacture, which is why water activity and preservatives matter.