Cannabis 101

Why is it so important to test cannabis products? 

Published on November 4, 2022 · Last updated November 8, 2022

Testing cannabis products is essential for consumer safety—it ensures that cannabis consumers can buy products that have been approved by a licensed lab and are safe for consumption. One of the main benefits of cannabis legalization is that a state or nation will set up an agency to regulate the quality of cannabis products that are sold in that new market. All products are tracked in a legal market, and if an issue arises with a batch, a product can be recalled and consumers notified. 

When you buy weed from the illicit market, you never know what you’re going to get. You might get weed that is moldy, drenched in pesticides, or more, which can make you ill. In 2019, the EVALI/VAPI outbreak stemmed from illicit cannabis sellers adding thickeners to vape cartridges that were not approved for consumption. Sixty-eight people died and more than 2,800 were hospitalized as a result of consuming unregulated, untested cannabis products.

Regulating substances is nothing new—it happens with alcohol, prescription drugs, over-the-counter medicines, and other substances. In the US, alcohol is regulated at the federal and state levels, and drugs and medicines are approved and regulated by the FDA (U.S. Food & Drug Administration) to safeguard public health. 

We at Leafly fully support a regulated, legal cannabis market because it ensures that consumers can buy products that have been tested and are safe for consumption. 

New York loosened weed testing rules for mold and yeast—Here’s why

How cannabis regulation and testing works

When a state votes in legal cannabis, it usually takes a year or so before dispensaries open to the public and adults can actually go and purchase weed. Part of what happens during that time is  the creation of a regulatory agency to track and test cannabis products.

In most states, an existing medical marijuana agency, state health agency, or liquor agency will take over and expand into regulating adult-use cannabis, while in others, a completely new regulatory body may be created. 

Once the regulatory agency is established, licenses are issued to different groups in the state’s cannabis industry. The types of licenses vary by state but usually include:

  • Producers (growers and breeders)
  • Processors/manufacturers (extractors)
  • Testers (lab testers)
  • Retailers (dispensaries)
  • Distributors, wholesalers, researchers, and more

Cannabis is tracked through a computer system from seed to sale, or from creation to consumption.

Products are tested for safety after growers and extractors produce them, and must pass testing before they can be legally sold. Growers produce flower, and extractors produce concentrates and edibles. 

Cannabis testing regulations: A state-by-state guide

What is cannabis tested for?

Cannabis testing regulations vary state to state, but in general, products are tested to measure potency, so consumers are aware of their strength, and for contaminants or harmful substances.

what is cannabis tested for
(Josh Titus/Leafly)

Here’s what most states test cannabis for:

  • Potency (levels of THC, CBD, and often THCA and CBDA as well)
  • Chemical contaminants 
    • Pesticides
    • Residual solvents used in extraction
    • Heavy metals, which can largely be uptaken by plants from soil
  • Microbial contaminants
    • Mold
    • Mycotoxins, or harmful substances produced by mold
    • Bacteria, usually from soil or feces
  • Physical contaminants (human hair, insects parts, and more)

Differences occur between states, and some require a test for water activity instead of mold, which is a measure of how much water is available in a product in order for mold to grow.

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Growers and extractors can also opt for a more extensive terpene and cannabinoid profiling of their products. This is usually not required by state agencies in order to be sold—currently, only California and Michigan do require terpene testing—but many producers pay for this test to give their product a leg up in the competitive market. More and more, consumers want to know the specifics of what their cannabis is made of.


Potency tests measure the level of THC in a product, as a percentage. They also measure CBD, THCA, and CBDA. This is part of the “fun stuff,” or what you want to be in a product, as Nick Mosely, CEO of Confidence Analytics in Washington State said. This valuable information tells the consumer how strong a cannabis product is so they can properly dose it.

Cannabis flower typically falls in a range of 15-25% THC, and concentrates usually between 50-80% THC, or even higher. 

“Potency is often inflated,” said Mosely. “It’s hard to accurately measure cannabinoids, and if you’re going to do a sloppy job, you’re probably going to end up biasing on the high side.”

What is a cannabinoid?

Chemical contaminants


Chemical pesticides can be used on cannabis plants during the growing process, so testing needs to be performed to determine if a product has a safe level for consumption. If too many pesticides are used, the cannabis product is rejected and cannot be sold in a legal market. 

“[Pesticides] should be of the greatest concern because it is unknown what the consequences of smoking pesticides are, and we do see pesticides in cannabis products regularly,” said Mosely.

Not all cannabis is grown using pesticides. Some use organic pesticides such as neem oil, or beneficial insects—good bugs that eat pests that damage the plant—or no pesticides at all. 

Residual solvents

When making certain cannabis concentrates, chemical solvents such as butane, propane, and others are used during the extraction process and then purged before the product is refined and packaged. Testing needs to be done on these products to make sure they have a level of residual solvents that is safe for consumption. 

Additionally, these solvents can have contaminants. Mosely explained how extractors can use almost pure butane in their extraction process, but that a filling tank may have traces of a chemical called benzene, which they see often, which can end up in the final product.

Heavy metals

The cannabis plant can uptake chemicals from the soil it’s growing in. “​​It is a great plant for soil remediation,” said Mosely. “Unfortunately, if the soil does have metals in it, now you’re getting metals into the plant.”

Metals can also make their way into the plant via the manufacturing process or when cannabis flower is dried on metal racks that aren’t food grade. 

What are cannabis terpenes and what do they do?

Microbial contaminants


Nobody wants to smoke moldy weed, but the actual concern with mold is inhaling mycotoxins, which are harmful substances produced by mold. They appear like a residue on cannabis flower. All states test for mycotoxins. 

Mosely explained how Washington and other states have done away with testing for mold and yeast and are focusing on mycotoxins instead. “[Those] are the things that are really going to get you sick. Mycotoxins can cause acute liver damage and also long-term exposure can lead to cancer,” he said.

Mold and water activity

Many states still do test for mold, but some have switched to testing for water activity, which is a measure of how much water is available for microbial growth, according to Mosely. If the water activity is below a certain threshold, that means mold can’t even grow, giving cannabis flower a long shelf life. 


Testers also look for a variety of bacteria, including E. coli, salmonella, and others, that usually come from soil or feces. These can often find their way onto cannabis plants in an outdoor setting, if plants are laid on the ground after harvesting, or if dirt is somehow sprayed up onto plants.

Physical contaminants

It might seem like a no-brainer, but cannabis products do come to testers with foreign materials in them. Testers do a visual inspection, mainly looking for insect parts, rodent feces, human hair, and more, according to Mosely. Finding any of these will result in a failed test.

Terpene and cannabinoid profiling

Some growers and extractors will pay extra to get an analysis of the terpene and cannabinoid composition of their flower or concentrates. Although usually not required by law, many consumers want these analyses to more fully see the chemical profiles of their cannabis products.

For example, Confidence Analytics can test for up to 17 cannabinoids and 48 terpenes, which is only a fraction of what the plant can produce. Any cannabinoid or terpene that you want to label on your package, you have to test for, said Mosely. You can’t just claim to have it. 

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Pat Goggins
Pat Goggins
Pat Goggins is a former Leafly senior editor who handled the site's informational Cannabis 101 and Learn section content, as well as health and science, and growing articles. When not fixing typos or reading a book, you’ll probably find him on a boat or in the mountains.
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