Colorado audit finds marijuana testing gaps and delayed warnings

Nearly 75% of marijuana processed for eventual sale lacked pesticide tests, 2023-2025

A Colorado state audit released Monday found that inconsistent oversight by the Marijuana Enforcement Division, which regulates Colorado’s first-in-the-nation legal recreational marijuana market, potentially put consumers at risk of using contaminated products. The report pointed to inconsistent agency oversight and what it described as loose state rules around testing marijuana products or contaminants. Nearly 75% of marijuana processed for eventual sale from 2023 through 2025 did not undergo pesticide testing, while auditors also found missed inspection schedules, insufficient random checks at dispensaries for contaminated products and delayed public warnings. Auditors said the deficiencies increased the risk of contaminants or inaccurate potency labels but found no evidence of “widespread health and safety issues.” ProPublica produced the article in partnership with The Denver Gazette.

Testing rules and self-sampling

Colorado allows marijuana businesses to test far less frequently than state guidelines require if they can show consistent compliance with testing rules. The audit said the reduced testing program results in “a significant portion of the marijuana product being sold in Colorado not undergoing testing to ensure it is safe.” Manufacturers can also use other testing exemptions, including for certain marijuana-derived skin and body products, but auditors found “limited MED oversight” of how companies determine they qualify.

The audit also highlighted the absence of independent collection of samples for safety testing after the issue had been raised repeatedly. The Denver Gazette and ProPublica found that more than half of states with regulated marijuana markets rely on private labs or an independent third party to collect samples. Colorado businesses are free to collect the samples they submit for testing.

MED investigators told auditors that, as a result, Colorado relies largely on “an honor code” to ensure the safety of marijuana sold in state dispensaries. Auditors said allowing businesses to select their own samples “increases the risk that businesses do not pick samples that are representative of the overall quality of their marijuana product.”

At the start of the year, MED regulators planned to overhaul testing by requiring private laboratory personnel to collect samples, then abandoned the proposal after manufacturers said it would increase their costs. On Monday, Deputy Senior Director Kyle Lambert told legislators the agency chose not to pursue the overhaul this year, chiefly because he said it would be a geographic challenge to do away with self-sampling for rural businesses. “It was decided now wasn’t the right time to propose that as a policy change,” Lambert said.

State Sen. Byron Pelton, a Republican from Sterling, pushed back and said he thought MED should close what he considered a loophole allowing businesses to collect their own samples. “If I’m a shady character, I know which products I’m going to go sampling and which ones I’m not,” Pelton said. “That’s a pretty gray area to me.”

Warning timelines and audit findings

State auditors found that unsafe products remained on the market for as long as three years before MED issued a public warning. Their review of health and safety advisories found that, on average from 2023 through 2025, contaminated products covered by an advisory remained on shelves for more than seven months. That was the same interval The Denver Gazette and ProPublica had found before warnings were issued in their investigation.

MED took an average of three and a half months in 2025 to issue an advisory after opening an investigation into potential contamination. Even after investigators determined an advisory was needed, the agency took a month on average to issue one. The audit said: “These issues limit MED’s ability to meet its core objective to identify product safety risks and to help ensure that licensed marijuana businesses meet product safety requirements.” It added: “As a result, there is an increased risk that marijuana products sold in Colorado may have contaminants or that the potency listed on the labels is inaccurate.”

A separate survey of MED investigators found that more than half said there are or may be widespread marijuana product safety issues in Colorado’s regulated market.

Documented product cases

The Denver Gazette and ProPublica reported last month that a Colorado manufacturer voluntarily flagged 49 of its popular marijuana vapes for recall, nearly six weeks after a third-party laboratory notified the company and regulators that it had detected methylene chloride. The Environmental Protection Agency has sought to ban the chemical for most uses because it can cause cancer. MED issued a health and safety advisory a day after the publications first reported that the manufacturer had warned dispensaries to stop selling the vapes, which consumers had been purchasing for over a year.

Another case highlighted by the newsrooms involved a marijuana sleep aid pill that took 15 months for its manufacturer to discontinue production after consumers warned regulators that the product was harming their livers. The pills contained herbal extracts that researchers say can cause liver damage.

Converted hemp timeline

The audit’s conclusions echoed several findings from The Denver Gazette and ProPublica’s investigation this year into how MED addressed contaminants entering the legal marijuana marketplace. On Jan. 29, 2026, the newsrooms reported that intoxicating hemp had seeped into Colorado’s marijuana market because the state had failed to adopt safety measures. Tests found signs of hemp in vapes sold at marijuana dispensaries.

On Feb. 6, 2026, Colorado regulators discussed a proposal to replace manufacturer-selected samples with collection by independent laboratories or contractors. On Apr. 13, state regulators announced a plan targeting companies that illegally sell cheaper and potentially hazardous hemp products as marijuana, citing potential tax avoidance and “serious risks to public safety.”

On May 15, 2026, a top MED official acknowledged in a meeting with industry representatives that the amount of chemically converted hemp being sold as marijuana was greater than the agency had publicly disclosed.

On May 14, 2021, after hemp companies figured out how to convert CBD into the high-inducing compound THC, Colorado became one of the first states to ban chemically converted hemp products, first with regulatory advisories and later through legislation. President Donald Trump signed the Farm Bill on Dec. 20, 2018, legalizing hemp. Congress’ intent was to help farmers and people who believe hemp’s high levels of the nonintoxicating compound CBD can help with seizures, pain and sleep. Colorado became the first state to allow retail sales of marijuana for recreational use on Jan. 1, 2014.

MED response and enforcement

In a statement released Monday night, MED emphasized that auditors found no evidence “to support claims of widespread health and safety issues” with marijuana products for sale in Colorado, while agreeing that the audit identified areas for improvement. MED said it would assess testing exemptions currently allowed under state laws and regulations. Dominique Mendiola, MED’s senior director, said the audit “allows us to take a critical look at how we can continue to carry out our work, consistent with our commitment to integrity, safety, and continuous operational improvement.”

The audit also questioned MED’s reliance on businesses voluntarily recalling contaminated marijuana products, saying “some of these recalls did not succeed at stopping the businesses from selling potentially unsafe product.” Lambert also said the agency still might revisit independent collection of samples.