The standard cannabis contaminant panel covers seven groups: pesticides, heavy metals, microbials, mycotoxins, residual solvents, foreign matter, and water activity or moisture. Most US state programs require a licensed lab to screen every batch against these categories before the product reaches a dispensary shelf. Vapor products add a screen for vitamin E acetate and other diluents.
The Core Contaminant List
Pesticides
Labs screen flower, trim, and concentrates for dozens of active ingredients, including myclobutanil, imidacloprid, abamectin, bifenazate, and paclobutrazol. Many of these are banned for cannabis because they are not registered for the crop, and some break down into harmful compounds when heated. Results are reported in parts per million or parts per billion and compared to a state action limit.
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Heavy Metals
Arsenic, cadmium, lead, and mercury top the list. Plants pull these from soil, water, and nutrient mixes, and concentrates can raise the concentration because the metal does not evaporate with the solvent. Inhalation is the main exposure route for flower and vape cartridges.
Microbials
Total aerobic bacteria, total yeast and mold, and specific pathogens: Aspergillus species, Salmonella, and Shiga toxin producing E. coli. Mold counts matter most for people with compromised immune systems or lung disease. Some states require Aspergillus testing on inhalable products only.
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Mycotoxins
Aflatoxins and ochratoxin A are toxins produced by mold that can survive drying and curing. They are carcinogenic at low doses and are tested separately from live mold counts.
Residual Solvents
This category applies to extracts. Common analytes include butane, propane, ethanol, heptane, hexane, pentane, benzene, toluene, and xylene. Labs measure what is left behind after purging, in parts per million.
Foreign Matter and Filth
Hair, insect parts, rodent hair, sand, and plastic fragments. Labs use visual inspection plus microscopy. Some states fold stems and seeds into this category.
Moisture and Water Activity
Water activity above roughly 0.65 supports mold growth after the test is done. This is a stability check rather than a contaminant, but a failed result blocks sale.
How to Read a Contaminant Report
- Find the lab name, license number, and accreditation on the certificate of analysis.
- Match the batch number and sample ID on the report to the label on the package.
- Check the sample date and the report date. A test older than the batch it covers is a mismatch.
- Confirm each analyte lists a measured result and a pass or fail against the state limit.
- Look for the action limit column so you can see how close the result sits to the threshold.
- Read "ND" as not detected, which means the analyte fell below the method detection limit, not that the lab skipped it.
- Verify the report covers the product form you bought. Flower, oil, and edibles use different panels.
Limits Vary by State
There is no federal standard for cannabis. Each state sets its own list of analytes and its own action limits, and some states test fewer compounds than others. A product that passes in one state may fail in another. A certificate is only meaningful against the rules of the jurisdiction that issued it.
What the Panel Does Not Cover
A contaminant panel does not confirm potency accuracy beyond the reported cannabinoid numbers, does not measure terpenes unless that test is ordered, and does not evaluate compounds formed when the product is burned. It also says nothing about storage conditions after testing, which can change moisture and microbial results over time.