What Might Be Lurking In Cannabis?

Cannabis, like all other natural products, are subject to contamination by a number of different types of biological and chemical contaminants. Some of the primary contaminants found in Cannabis include harmful bacteria and fungi, mycotoxins, agrochemicals, metals and foreign matter.

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Consumers with compromised immune systems are the most vulnerable to Cannabis contaminants like harmful mold spores, mycotoxins, bacteria, and agrochemicals.

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TYPES OF CANNABIS CONTAMINANTS

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Bacteria and Endotoxins

Primary Source of Contamination: Post-Harvest Processing

Cannabis, like any other natural product, is subject to contamination by various forms of bacteria, some of which could be harmful, like Salmonella and certain strains of E. coli. When these bacteria are consumed, the body's immune system kicks in to get rid of them. As the bodies of the bacteria break down, endotoxins are released which can trigger severe, sometimes life-threatening reactions, like septic shock.

To prevent bacterial contamination of Cannabis, always handle Cannabis with clean hands. If you are a cultivator, always ensure that surfaces that come into contact with Cannabis are sterilized before and after contact, keep Cannabis away from contact with pets, and ensure any workers that are handling Cannabis wear gloves and exercise proper hygiene.

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Yeasts, Molds, and Mycotoxins

Primary Source of Contamination: Cultivation, Post-Harvest Processing, Storage

In addition to bacterial contaminants, there are a number of fungal contaminants which may end up in Cannabis and Cannabis products. Yeasts and molds are two different types of fungi. Yeasts are very small, reproduce by budding, and have a smooth appearance when visible. Whereas molds are typically larger, grow by extending threads of hyphae, and have a rough, fuzzy appearance. Some molds, like many dark molds, and their spores, can be toxic to the human body.

​In addition, some molds excrete toxic chemical byproducts called mycotoxins. Mycotoxins can be particularly troublesome because they persist even after the fungus that produced them is dead and gone. Mycotoxins can also become concentrated in Cannabis extracts. Little research on the prevalence of mycotoxins in Cannabis has been performed and published, to date, so it is unclear whether mycotoxins in Cannabis are a significant public health risk or not.

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Agrochemicals

Primary Source of Contamination: Direct Contact During Cultivation, Contaminated Water and Growing Media

Agrochemicals are chemicals used in agricultural operations and include things like pesticides, fungicides, herbicides, and plant growth regulators. Many agrochemicals are petroleum based and mix readily with other oils, like the trichomes on Cannabis flowers. In addition, some pesticides penetrate plant tissues and form reservoirs of pesticide in the plant itself. Chronic exposure to some agrochemicals can cause serious medical disorders including neurodegeneration among others.

Agrochemical contamination is of special concern for concentrated Cannabis extracts, like "dabs", because most agrochemicals are chemically similar enough to terpenoids and cannabinoids that they, too, will become concentrated during processing.

Concerned about a certain pesticide? Visit the Pesticide Properties Database to lookup a pesticide and learn about how it affects the environment and human health.

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Metals

Primary Source of Contamination: Contaminated Soil or Water

Cannabis has the ability, like many opportunistic plants, of tolerating the accumulation of metals in its tissues. Some researchers have begun exploring whether Cannabis' ability to tolerate metal accumulation could be used to remediate soils contaminated with metals. When humans ingest metals, it can be very problematic. The human body will steadily accumulate metals, eventually reaching a tipping point where the metals begin causing tissue damage and disruption to normal physiological signaling.

Little research has actually been performed on this subject to determine whether metal contamination of Cannabis products is a significant public health risk.

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Additional Resources

WHO Guidelines for Assessing Quality of Herbal Medicines
Pesticide Use in Cannabis - Cannabis Safety Institute
Determination of Pesticide Residues in Cannabis Smoke
​Heavy Metal Tolerance and Accumulation of Cd, Cr, and Ni in Cannabis Sativa
Levels of Selected Metals in Leaves of Cannabis sativa Plants Grown in Ethiopia
Cannabis Microbiome Sequencing Reveals Several Mycotoxic Fungi Native to Dispensary Grade Cannabis Flowers
Fatal Aspergillosis Associated with Smoking Contaminated Marijuana in a Marrow Transplant Recepient
Understanding Dabs: Contamination Concerns of Cannabis Concentrates

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