Cannabis Testing: What Are Regulators Checking For?

Did you know how much testing goes into your cannabis to provide safe consumption?

Hand wearing blue gloves holding a vial filled with golden yellow liquid with cannabis in the background Photo credit: Shutterstock

When regulators check to make sure legal cannabis is safe and up to par, what standards is that cannabis supposed to be meeting?

When cannabis of any form is legalized, it also becomes subject to regulation. The product must be run through several tests to ensure it’s safe for consumption before it’s allowed to hit shelves. But what exactly would make cannabis unsafe? What are the regulators testing for? It turns out that answer varies depending on which state you’re in. Most, however, require testing for a few key things: potency, pesticides, heavy metals, and contaminants.

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Cannabinoid Content

Every single marijuana product you purchase will tell you how much of a ride you’re in for when you ingest the substance. If it’s marijuana flower, the plant’s THC content will be expressed as a percentage on the front of the packaging. If you have an edible, the THC will be expressed as a weight or volume. The same is true of other cannabinoids like CBD, CBG, Delta-8, Delta-10 and so on. That regulation is similar to alcoholic beverages expressing their alcohol content on the packaging.

White cannabis plastic container with THC warning and other cannabinoid potencies with a green nugget in front

All cannabis products will have a break down of cannabinoids on the label. Photo credit: Creative Commons

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The goal there is to help guide consumers, so they know how much of the product to ingest. Edibles will often have suggested serving sizes written onto the packaging. That detail is extremely important, since products can vary widely in their potency. 


Testing for pesticides is common practice for marijuana regulators. That’s with good reason, too. In Maine, people fell ill after ingesting medical marijuana that, when tested, came up positive for multiple different types of pesticides, along with solvents, rubbing alcohol, mold, and bacteria. 

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Man looking at a neon green pesticide bottle in a grocery store

There a strict pesticide regulations in most states with recreation and medical cannabis. Photo credit: Shutterstock

In Delaware, pesticides are the only contaminants specified for what regulators have to look out for. Florida specifies that marijuana growers can use pesticides, but only if that pest killer is registered with the Florida Department of Agriculture and Consumer Services. In contrast, Massachusetts prohibits any kind of pesticide whatsoever, including organic ones. 

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Heavy Metals

Heavy metals within earth’s crust break apart and mix with soil, sometimes in high quantities because of mining and industrial agriculture. The ones the FDA is most concerned about are mercury, cadmium, lead, and arsenic, all of which can lead to severe illness after exposure to even small amounts. The marijuana plant absorbs those metals very readily, so cannabis regulators are tasked with testing marijuana products to ensure they don’t have toxic levels of those metals present. 

A hand in blue gloves pulling up a vile labeled, "Heavy Metals - Test"

Heavy metal testing is searching for toxic quantities that can gravely affect health. Photo credit: Shutterstock

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Almost all states require testing for the presence of heavy metals in marijuana products, with Delaware and New Hampshire as exceptions. Maryland requires testing for those metals be completed during both the cultivation and processing stages. That state looks out for nickel, chromium, and manganese on top of the list of usual suspects.

Mold and Mildew

Any plant is at risk of developing mold and mildew and almost all marijuana contains at least some small amount of mold spores. However, high levels of those spores can be poisonous to humans. Since marijuana is purposely dried before being sold, processors have to be careful that cultivating and curing is done correctly, without exposing the plant to lingering humidity that could lead to the development of fungus.

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A green cannabis nugget with white fluffy mold on it

Mold like powdery mildew can be harmful when smoked. Photo credit: Shutterstock

Colorado, Nevada, Maine, Illinois, and Massachusetts all use the same form of test to check for total yeast and mold count (TYMC), which search for microbial cells numbers within the sample. 

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Toxins and Additives

Since the FDA mandates testing for things that could make you sick, most legal operators won’t include anything below the board. Marijuana purchased on the Black Market isn’t subject to the same type of scrutiny, and has even been found to be laced with other drugs like meth and fentanyl. In some cases, additives to illicit marijuana have proven deadly.

You might remember headlines in 2019 talking about people winding up with lung illnesses after using e-cigarettes and vapes. Investigators discovered 2,051 people with lung injuries from 49 states, plus Washington, D.C. and the U.S. Virgin Islands. 39 people died from that condition, the CDC says

Researchers tracked the illness back to an additive, vitamin E acetate, which is found in foods, supplements, and cosmetic products. It was also being used to dilute vaping liquid.

“Vitamin E acetate does not usually cause harm when swallowed as a vitamin supplement or applied topically to the skin.  However, previous non-CDC research suggests that when vitamin E acetate is inhaled, it may interfere with normal lung function,” the CDC stated in a briefing after a slew of people got sick from their vapes.”

As a result, some states began banning the additive, even though those who got sick had almost entirely been using illicit products bought on the Black Market. As a precaution, Colorado and Ohio outlawed the product altogether for use in vape or e-cigarette liquid; Michigan later did the same.

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The State of Washington issued a voluntary recall for any cannabis products that contained vitamin E acetate, though none did. Massachusetts issued a temporary quarantine on all vaping products until they could be tested for vitamin e acetate.


There can be other contaminants found in marijuana, too. Microbes are a very common one, forming when the product is stored or prepared improperly. Harvesting it while it’s wet or trying to leave it to dry in humid conditions can lead to those contaminants. 

Bright green cannabis leaves with a humidity reader next to it

Humidity is a huge factor for other contaminants that states test for. Photo credit: Shutterstock

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In Florida, the law requires only that the product be tested for “contaminants unsafe for human consumption” but it does not specify what those contaminants might include, and there doesn’t seem to be a clear standard on what testing should entail. Florida does also require cannabinoid content to be listed on the packaging. 

Other Tests

Some states have stricter regulatory rules than others. In California, marijuana isn’t just tested for additives and potential contaminants, but also things like moisture content, water activity, and homogeneity. 

In Hawaii, state law requires labs test for intestinal bacteria and pathogens – things that are not specifically mentioned in most other states’ laws. That state and Illinois mandate the labs test for solvents.

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New York and Colorado require testing for E. coli and salmonella on top of the usual suspects.

Testing Issues 

The roll-out of standard practices in testing hasn’t always gone smoothly. In Alaska, for instance, the Alcohol Marijuana Control Office released a Cannabis Testing Laboratory Report showing local labs might not be getting accurate results. Measurements of potency and contaminants varied between testing facilities, one of which wound up closing

California had similar struggles. A lab director at Sequoia Analytic Labs in Sacramento was accused of falsifying pesticide reports in 2018, leading to recalls on 29 marijuana firms.  

Cannabis Testing: What Are Regulators Checking For? was last modified: by