Misinformation may be putting consumers at risk when it comes to cannabis safety. A recent XRPure survey revealed that 91.7 percent of Americans believe medical cannabis should be decontaminated, and 90.5 percent think brands should label if a product has been treated. However, most people don’t understand the options for decontamination and the processes behind them. In fact, only one in four respondents (26.4 percent) reported feeling confident in their knowledge of available methods, such as X-ray, ozone, or radiofrequency (RF) technologies.
This gap in understanding is more than just a lack of information; it poses a significant public health risk. Decontamination removes harmful microbials and helps protect cannabis consumers. It is particularly crucial for medical cannabis, as medical patients may face more severe or even life-threatening risks from exposure to these contaminants.
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Common Cannabis Microbes
Some of the most common cannabis microbes are Aspergillus, Salmonella, E. coli, powdery mildew, as well as other types of yeast and mold. Here’s a brief breakdown of each:
Aspergillus is a toxic mold that can produce aflatoxins (toxic compounds). Characterized by greenish-black mold, it may contaminate cannabis at various stages of its production–from initial cultivation to drying, curing, and storage. Certain forms can cause aspergillosis, a potentially fatal lung infection, and may pose a higher risk to those who are immunocompromised. Exposure to Aspergillus is most common through inhalation of cannabis through smoking or vaping, or consumption. It has been identified by several states as one of the greater threats to public health, and as such, cannot be present in samples of dried cannabis.
Salmonella is a bacterial pathogen often associated with food contamination, but it can also be present in cannabis if sanitation and handling practices are not up to standard. Salmonella contamination can occur at any stage of cannabis production, including cultivation, harvest, processing, or packaging, and usually stems from fecal exposure. Those who are infected with Salmonella may be at risk of gastrointestinal illness; however, for individuals with weakened immune systems, the symptoms can be more severe or even life-threatening. Salmonella is more likely to be present in contaminated edibles or non-inhalant forms of cannabis like tinctures, oils, and concentrates.
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Escherichia coli (E. coli) is a bacterium that can be found in contaminated soil, water, or surfaces. It can enter the cannabis supply chain through poor hygiene or unsanitary conditions. While many strains are harmless, some can cause gastrointestinal illness or more severe conditions. Similar to Salmonella, E. coli is a bigger concern in cannabis edibles, especially those involving raw ingredients, where bacteria can thrive if ingredients are not cooked properly.
Powdery mildew is a fungal disease that first appears as white, grayish, powdery-like spots on cannabis leaves, stems and sometimes buds. While powdery mildew is often viewed as a cultivation issue, as it reduces plant yield and can compromise their potency and purity, it can also pose health risks to users. Those who smoke, vape, inhale or ingest cannabis contaminated with powdery mildew may be at risk from minor irritation symptoms, like cough and sore throat in healthy consumers, to more serious conditions like fungal infections in immunocompromised individuals and respiratory infections in medical cannabis patients.
Not all yeast and molds found in plants pose harm. However, states will often conduct total yeast and mold counts (TYMC), which are key microbiological tests to capture the total number of viable yeast and mold colonies in a sample. High counts indicate improper handling, storage, or sanitation, as well as the presence of harmful molds that may trigger conditions like allergic reactions or cause fungal infections, especially for those with vulnerable immune systems.
Decontamination Methods for Cannabis
When looking to decontaminate cannabis to rid the plant of microbes, operators have many options to choose from, each of which comes with pros and cons. Some of which are:
X-Ray
How it works: X-ray decontamination uses ionizing radiation generated by high-energy X-rays (typically from an X-ray tube) to kill or inactivate microbes by damaging their DNA and cellular structures. It does not apply heat during the process and offers deep penetration, similar to gamma ray decontamination, but with on-demand energy generation (no radioactive materials).
Pros:
- Highly effective on mold, bacteria and spores
- Deep penetration
- No radioactive materials and on-demand
- Preserves the integrity of terpenes and cannabinoids
- Machines can be installed on-site in grow facilities
- Can be used on packaged products
Cons:
- High initial equipment cost
- Equipment must have radiation shielding and be compliant with safety regulations
- Limited number of providers
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Gamma Ray
How it works: Gamma-ray irradiation typically uses Cobalt-60, a radioactive isotope commonly used for sterilization, to disrupt microbial DNA. Gamma emits a constant stream of radiation that cannot be turned on and off.
Pros:
- Highly effective against all microbes, including spores
- Deep penetration and great for large, dense flower or bulk product
- No heat or moisture, so the product form is preserved
Cons:
- Uses radioactive materials – strictly regulated and licensed
- Must be done at off-site facilities
- Terpene degradation at high doses
- Long set-up times; not ideal for on-demand decontamination
Ozone
How it works: Exposes cannabis to ozone gas (O₃), which oxidizes and destroys microbial cells.
Pros:
- Effective for mold, mildew and bacteria
- Non-toxic, no chemical residue if applied properly
- Ideal for air and surface sanitation
Cons:
- Ozone is toxic to humans in high doses
- Generally considered a surface treatment and may not penetrate dense buds
- Cannot be used on packaged product, requires exposure to the gas
- Can degrade terpenes and cannabinoid profiles if overused
- May dry or discolor the product
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Radiofrequency
How it works: Uses electromagnetic waves (typically at 27.12 MHz) to produce heat within the cannabis flower. This internal heat destroys microbial contaminants.
Pros:
- Non-chemical and residue-free
- Penetrates deep buds
- Quick treatment times, only a few minutes per batch
- Kills mold, yeast and bacteria
Cons:
- Risk of overheating, which can degrade terpenes, overdry buds and damage flower structure
- High initial equipment cost
- Effectivity is highly dependent on moisture content
- Batch size limits; may need multiple units to do large volumes
Microbial contamination of cannabis is a concern for all users, especially for medical cannabis patients who may be more vulnerable to infection. Microbes such as Aspergillus, Salmonella, E. coli, powdery mildew, and total yeast and mold can affect both the safety and quality of the plant. For this reason, it is important for operators to decontaminate their cannabis. Several options, including X-ray, gamma irradiation, ozone treatment, and radiofrequency, are available. Choosing what works best for each operator depends on their specific needs and the products they are producing. However, the goal remains the same: keeping cannabis clean, safe, and effective for all consumers.
*This article was submitted by a guest contributor. The author is solely responsible for the content.