Michael Bell, a chemist at SC Labs, tests marijuana samples for potency at the company’s Denver facility on April 7, 2025. SC Labs analyzes cannabis products to ensure they’re safe for human consumption. (Photo by RJ Sangosti/The Denver Post)
As the first state to legalize recreational marijuana, Colorado has been a leader in establishing industry regulation to help ensure products are safe for human consumption. More than a decade later, though, gaps in testing oversight still allow contaminated cannabis to reach store shelves.
Since 2019, the state’s Marijuana Enforcement Division, known as MED, has issued 63 recalls for cannabis products contaminated with bacteria, fungus, pesticides, heavy metals or other chemicals above the legal limits.
Though these products are subject to strict testing, regulators have found companies that circumvent the requirements by selectively picking the samples they self-submit to third-party labs. Testing companies say growers and manufacturers will also choose testing partners based on which offers the most desirable results — a practice known as lab shopping.
Some companies have been caught not testing their products at all. Colorado regulators fined more than 40 cannabis cultivators and manufacturers over the last five years for failing to comply with testing requirements, The Denver Post’s analysis of enforcement data found.
The vast majority of recalls concerned marijuana flower and pre-rolled joints that exceeded the thresholds for mold, yeast and a fungus called aspergillus. Concentrates contaminated with pesticides and other solvents were also occasionally recalled, as were vape devices that contained unapproved ingredients and flower that contained heavy metals. In one instance, MED identified edibles causing potential liver injury.
Over the last five years, Colorado regulators increasingly penalized cannabis companies that violated testing procedures, enforcement data shows. But critics in the marijuana industry say the state’s efforts are still insufficient and, further, enable bad actors in the marketplace.
In mid-March, San Luis Valley-based cannabis company Mammoth Farms sued MED, alleging it has failed to uphold its statutory duty to protect consumers. Among its complaints, Mammoth Farms accused the agency of ignoring companies that are diverting legal weed to illicit markets in other states and replacing the Colorado supply with synthetic or hemp-derived tetrahydrocannabinol (THC).
Converting hemp cannabinoids, like cannabidiol (CBD), into THC requires chemical solvents such as methylene chloride. The lawsuit alleges one company widely sold products contaminated with this solvent, unnoticed, because the state does not require testing for it before products go to market. Last June, MED recalled vape cartridges tainted with methylene chloride.
Justin Trouard, CEO of Mammoth Farms, said the recall came months after he alerted the agency to the producer, allowing toxic vapes to reach consumers. Inhaling methylene chloride can cause harm to the nervous system, according to the Environmental Protection Agency. Prolonged exposure can cause liver toxicity, liver cancer and lung cancer.
“There’s certain people that the only way they can stay afloat is if they cheat the system. That is their market advantage,” Trouard said. “The MED does not put parameters in place to be able to catch people for these things.”
MED recently defended its actions in an industry-wide bulletin, touting the vape-cartridge recall and continuing efforts to investigate allegations regarding hemp-derived cannabinoids. In 2021, the agency also suspended one company’s license for three years after finding it used THC from hemp to make regulated marijuana products.
“The MED is proud of the work it does and expects licensees to also prioritize measures to prevent youth access and ensure the safety of products they make available to consumers,” the state bulletin said.
Justin Singer, CEO of edibles maker Ripple, has also criticized MED for a lack of quality assurance oversight. Frustrated by inconsistencies in the cannabis concentrate he received for commercial purposes, Singer independently purchased flower, shake and pre-rolled joints from dispensaries and sent them to third-party labs to test for potency and contaminants.
The potency for 12 of the 15 products was significantly overstated, the results showed, and four of the samples exceeded the state’s limit for yeast and mold. The samples were also tested for things MED does not currently require, such as aerobic bacteria and coliform, the latter of which can be a sign of potential pathogens, Singer said. Two products exceeded the hemp thresholds set for permissible aerobic bacteria and four had detectable amounts of coliform. (Hemp and marijuana are both cannabis plants, but subject to different regulations because of their different consumer uses.)
Singer said the results show MED’s priorities are misplaced by trying to accommodate the industry during a market downturn.
“You need oversight, you need surveillance and you need to stop making excuses for businesses that can’t deliver clean products,” he said.
MED told The Post it was aware of the study, but “to our knowledge (it) has not been vetted as valid or verified.” Nonetheless, the results prompted state Sens. Byron Pelton, R-Sterling, and Rod Pelton, R-Cheyenne Wells, who are cousins, to call for an audit of the agency’s enforcement practices, its responsiveness to safety concerns and the adequacy of current compliance measures.
Michael Bell, a chemist at SC Labs, tests marijuana samples for potency at the company’s Denver facility on April 7, 2025. (Photo by RJ Sangosti/The Denver Post)
Gaps in testing
Colorado is unique in allowing marijuana companies to submit their own test samples, said Josh Wurzer, chief compliance officer at SC Labs, which operates in five states where marijuana is legal.
SC Labs runs a testing facility in Denver where licensed transporters deliver samples on behalf of producers. But elsewhere in the U.S., Wurzer said his staff is usually tasked with collecting samples from cultivations or manufacturing facilities to ensure they are representative of the batch at large.
“That’s kind of the weak link in the chain,” Wurzer said.
MED has fined 63 companies in the last five years that it found violated testing procedures, The Post found. That includes 24 instances in which companies were cited for doctoring their samples sent for testing, either by drying them in dehydrators, passing them through ozone machines, or treating them with hydrogen peroxide, among other methods.
Companies that adulterated samples were often found to do so in hopes of getting favorable results.
In one case, settled in 2022, sister companies Mayflower Group and Nutritional Elements were caught submitting different forms of marijuana flower to be tested for heavy metals and microbials. Investigators found the companies crumbled up flower and dried it ahead of microbial testing, which yielded passing results. However, whole buds from the same batch were found to have elevated levels of mold and yeast, state records show. Those buds were only submitted for heavy metals testing, the agency reported. The penalty was $15,000.
The number of violations related to testing increased in recent years as the agency both expanded testing requirements — for example, the state began requiring aspergillus testing in 2022 — and made it a focus of enforcement, MED spokesperson Heather Draper said by email.
The agency employs 27 investigators who are responsible for monitoring Colorado’s 2,200 marijuana businesses. In 2024, they conducted 160 investigations related to product safety, Draper said.
“The division has dedicated more resources to focusing on product safety measures, not only when it comes to testing, but also related to evaluating cultivation and manufacturing practices,” she said.
Over the last five years, investigators fined 41 companies that failed to complete the required testing of their products. In several cases, investigators found unsanitary conditions at the grows, such as mold growing on the walls and ceilings, that they believe motivated operators to intentionally circumvent product testing, settlement documents between MED and the companies show. The agency fined 10 total cultivators for unsanitary workplaces in the last five years.
One of the most egregious examples resulted in the closure of Denver cultivator The Training Fields in 2022. Regulators ordered the company to surrender its licenses and destroy its inventory after finding mold on the facility floor as well as mice, rat burrows, rodent droppings and “a possible raccoon nest in the ceiling,” according to MED’s report.
Additionally, regulators fined 10 companies that knowingly sold marijuana that had failed microbial, heavy metals or pesticide tests, and penalized six growers for using unapproved pesticides.
The grow room at the MedPharm Research warehouse, Dec. 7, 2018. (Photo by Hyoung Chang/The Denver Post)
While MED’s enforcement data shows instances of testing fraud and intentional noncompliance, some marijuana producers insist the bad actors are not representative of the industry as a whole.
MedPharm Holdings LLC, which grows under the Bud & Mary’s Cannabis brand, issued a voluntary recall in January after regulators found some of its flower contained elevated levels of yeast and mold. The recall states that the contaminated product had been sold between February and December 2024 at more than 50 stores throughout Colorado.
Lucas Nelson, group president of Bud & Mary’s, said in a statement that the company was alerted to the issue after regulators tested flower they purchased from a dispensary. The flower had been sent to a third-party lab and passed microbial testing before it was distributed to stores, he said.
Bud & Mary’s was unable to trace the issue to a specific root cause at the cultivation. Because it was “deli style” cannabis — meaning sold in bulk to dispensaries, where it’s displayed in large jars for customers to smell before purchasing — it’s possible something happened between the time the weed left the grow and when it reached store shelves, the company said.
Still, the recall prompted new internal protocols to ensure it doesn’t happen again, such as in-house testing and microbial surveillance.
“We remain committed to transparency, compliance and delivering safe, high-quality cannabis to our customers,” Nelson said.
Lab shopping
MED analyzes its available data to monitor compliance and proactively identify areas of concern, Draper said. It also routinely checks in with local businesses, sometimes designating specific topics for “themed inspections,” during which regulators can educate business owners on recent rule changes.
When it comes to testing, however, some of the data may not be reliable, according to experts in the field. The Post reached out to Colorado’s six licensed marijuana testing companies and heard back from two — SC Labs and AgriScience Labs, which are both located in Denver.
Representatives from each told similar stories of how cannabis producers sometimes choose testing partners based on which offers the most desirable results, a practice known as lab shopping. Once a dirty industry secret, Frank Traylor, owner of AgriScience, said lab shopping is no longer hush-hush, especially when it comes to potency testing.
“We had a customer that said, ‘Frank, we love you guys, but we make $10,000 more a month by testing with this other lab,’ ” he said. “Let’s say you fail pesticides at one lab but pass at another lab, where are you going to test? This is just obvious.”
Judith Marquez, an analyst at SC Labs, operates equipment used to test for pesticides in cannabis products in Denver, on April 7, 2025. (Photo by RJ Sangosti/The Denver Post)
Cannabis testing facilities fall under the purview of the Colorado Department of Public Health and Environment, which audits licensed labs every year, independently from MED. Testing companies have come under increased scrutiny in recent years after one based in Broomfield, the now-closed Rm3 Labs, was investigated for allegedly inflating potency results.
Regulators found that Rm3 Labs had cornered the market for potency testing by 2022 and intentionally inflated results by a significant margin through its sample preparation methods and equipment calibration errors, according to court documents. That led MED to suspend Rm3 Labs’ certification, which resulted in a 75% to 80% decrease in business, the company said in a January complaint filed against the agency.
Rm3 Labs addressed regulators’ concerns but closed in August 2022, about a month after MED reissued its potency certification. The company recently settled its lawsuit with the state.
“The decision to settle with the state was not taken lightly, and my family and I look forward to putting this dispute with the MED behind us,” Ian Barringer, owner of Rm3 Labs, told The Post.
Cannabis companies can also earn a Reduced Testing Allowance that, as the name suggests, allows them to test products less frequently than required. Producers secure this privilege by proving they have operating and cleaning procedures that support the production of safe cannabis.
Products must pass regularly scheduled testing for a specified window of time before the grower or manufacturer can apply for a Reduced Testing Allowance, which costs $4,200 annually. The testing frequency and window vary depending on the product.
This option, previously known as “process validation,” has been in place since 2013, Draper said. At any given time, about 300 licensees utilize the privileges, which are not static and can be revoked if a company’s processes change.
Wurzer said this practice hasn’t impacted his business much because many of his clients appreciate the value of regular testing. He believes that if cannabis companies did more upfront, the quality of products on the market would improve as a whole.
“I look at other industries who do way more testing than we’re doing and they’re doing it in-house or paying someone else to do it just for their own quality control,” Wurzer said. “I would want this testing anyways just to make sure my product is of a high quality.”
Lessons from California
Colorado isn’t the only state dealing with contaminated cannabis. Last summer, The Los Angeles Times and the WeedWeek newsletter published an exposé on the proliferation of pesticide-laden products in California dispensaries.
Reporters tested 42 legal marijuana products and found “alarming levels of pesticides,” with some containing as many as two dozen different chemicals, including some the state doesn’t test for because they are illegal. Regulators have largely failed to address evidence of widespread contamination in the legal supply, even after labs filed more than 80 complaints about the issue, the publications said.
Though damning, the findings inspired the formation of a new nonprofit organization called The Environmental & Consumer Compliance Organization, or ECCO, which is now offering a certification to help consumers identify brands that make clean weed.
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When companies join ECCO, they agree to have their marijuana tested at random every month. The organization’s field team gets products from dispensaries — primarily vapes and flower — and tests them the same day to ensure they have not been tampered with, said executive director Jen Lujan. Once they pass, members receive a certification seal to put on their product packaging and marketing materials.
So far, 13 California companies have joined ECCO, which began its testing in January. All members have so far passed testing, Lujan said. One product, made by a company that is not registered with the group, failed testing for the pesticide Chlorfenapyr, she added.
Lujan said ECCO’s goal is not to act as an enforcement agency but rather to elevate ethical brands in hopes of raising quality and safety standards throughout the industry. She hopes to expand the nascent nonprofit to other regulated markets, including Colorado, in the future.
“People go to the dispensary and they assume what they’re buying is not going to be toxic for them. Unfortunately, that’s not the case,” Lujan said. “We want to be able to say, ‘Let’s recognize these brands who are doing it right,’ and hopefully that will inspire others to want to do the same.”
