Every gram of the nearly 214 tons of weed sold at Michigan dispensaries last month came with a ream of data.
And every weed product sold in those dispensaries came with a label showing that it was checked for mold, heavy metals and potency.
All that testing is supposed to ensure that what you read on the package is what you get. But controversy has simmered for years over accusations that some potency numbers are inflated. Labs stand to make more money if their tests yield higher potency levels. Some have warned that mold testing, too, is insufficiently rigorous.
Here’s an introduction to cannabis safety and testing in Michigan, from reading a product label to how to file a complaint if you think the label isn’t accurate.
How weed gets tested
By state law, 0.5% of every batch of recreational cannabis has to be tested for safety and potency. That means a lab would have to test a quarter pound of pot from a 50-pound batch, the maximum allowable harvest batch size.
Steadfast Labs in Hazel Park, one of 23 laboratories in the state that are licensed to test recreational cannabis, buzzes with activity as it processes cannabis samples from dozens of growers or distributors.
At Steadfast, mold comes first. Technicians check the product ASAP in a sanitized area before it’s exposed to stray spores that are everywhere in the environment, including the lab. They use PCR (polymerase chain reaction) machines — the same kind of equipment used to process COVID-19 nasal swabs — to look for salmonella and several strains of aspergillus, a mold species that can cause serious illness in people with asthma or other health conditions.
From there, samples are divvied up and sent to testing stations across the lab.
At one station, they are put under a microscope, where another tech will look for stems or dirt or anything else that isn’t actually weed.
At another, Steadfast founder and CEO Avi Zallen showed off what he said is a half-million-dollar machine capable of searching for the residue of 60 different state-banned pesticides.
Another piece of lab equipment that looks a bit like an office printer breaks down cannabis samples using acid, heat and pressure. A different machine scans the broken-down sample for the heavy metals that occasionally get into weed through the soil that the flower is grown in.
A batch of weed needs to pass every safety test before it can be labeled and sold at a dispensary, though there’s nothing stopping a grower or distributor from taking a failed batch to a different lab for another try. Samples must pass testing twice on their second go-round.
Recreational weed must also be tested for potency, and that’s where the money is.
Experts insist that high levels of THC alone don’t guarantee a great high. But many customers seem to think otherwise. Weed with more THC fetches top dollar, which gives growers and sellers an incentive to produce weed with ever-higher THC levels.
Michigan puts legal limits on the strength of edible pot products. Cannabis plants can be as strong as the growers can make them, though experts say that cannabis biology puts a natural limit on its potential strength.
Michigan relies on cannabis testing laboratories to check the growers’ work.
Zallen said that in his view, a key to accurate potency testing is ensuring that the THC is evenly distributed throughout the sample. That way, test results are representative of the entire batch.
Steadfast uses a cryogenic mill for potency testing. The machine freezes samples to nearly 148 degrees below zero using liquid nitrogen (the cold ensures the particles don’t break down or stick together) then pulverizes the sample using a high-speed, magnet-powered grinder.
Any cannabis left over after testing must be destroyed after a 30-day retention period.
Can you trust Michigan cannabis labels?
Michigan is actually better than most states at regulating cannabis, said Bob Miller, chief scientific officer for ACT Laboratories, which tests cannabis in Michigan and five other states.
“Michigan really put some thought into it,” he said, noting that the state tests for more contaminants and requires more detailed sampling procedures than most. “I use Michigan as one of the examples.”
State regulators aren’t exactly sitting on their hands. In December alone, the state imposed fines on 10 different marijuana-related businesses — including a safety lab — for reporting failures or failing to perform quality checks on their lab equipment, among other problems. (To see details of disciplinary actions against individual retailers or labs, search the Cannabis Regulatory Agency’s licensing records for a business name.)
But Michigan did have a moldy weed scare in 2022, when a judge ordered the state to release about 32 pounds of recalled cannabis that had failed retesting for mold.
And the state hasn’t escaped the concerns about potency inflation that plague the industry in many places where pot is legal. In Colorado, for instance, an independent peer-reviewed study found that THC levels in many samples of recreational weed were typically inflated by more than 15%.
What’s on the label
Every recreational cannabis product, from flowers to gummies to brownies, comes with a small printed label that says when the sample was tested and which lab tested it.
That the label is there at all means the weed in the package was part of a batch that was tested against strict state standards for contamination. It means that the THC level listed on the package reflects tests conducted in a lab.
Want more details? Ask dispensary employees to look up the “certificate of analysis,” a multipage report with all the test results for the batch of cannabis used for a product.
What the label doesn’t say
Here’s the catch: There’s widespread agreement that all that testing isn’t producing consistent results, especially for potency. The cannabis testing labs licensed to operate in Michigan don’t have to use the same methods.
The state agency in charge of policing the cannabis industry, the Cannabis Regulatory Agency, has tried but failed so far to keep testing methods consistent.
The agency has pushed Viridis Laboratories, one of the largest testing facilities in the state, to change its potency testing methods but hasn’t been successful. And in 2021, the agency recalled almost 32 tons of Viridis-tested pot, alleging that the lab didn’t properly test plants for mold, leading to allergic reactions in more than a dozen people. (Viridis told Outlier Media these claims were unfounded.)
A judge partially reversed the recall, and the product was returned to dispensary shelves, according to reporting from MLive.
Viridis acknowledges that it uses a different method for potency testing than other labs, but says the method is accurate and approved by AOAC International, a nonprofit that validates lab testing methods.
“Our competitors were complaining about our potency methods and our THC numbers typically being three to seven points higher,” Todd Welch, chief operating officer and co-founder of Viridis, told Outlier. “We feel really confident that we are putting out the most accurate THC numbers in the nation.”
Those critics haven’t gone quiet even as the state has failed to change Viridis’ methods. When PSI Labs, a competitor, shut down its Michigan operation late last year, its director said it had struggled to compete without putting out inflated potency numbers.
Zallen, of Steadfast Labs, says his methods are at the cutting edge of the industry, but that his business has paid for its commitment to accuracy.
“If you’re low, you’re dead,” he said, adding, “Products that fail (at Steadfast) sometimes just go to other labs and pass. It’s possible it could happen innocently, but when it’s such an overwhelming pattern, you know that there’s a problem.”
Choosing a lab?
Under the current system, pot buyers are being asked to choose between competing labs’ highly technical explanations of why their testing method is best.
“It’s nice to have the safety net,” said a regular dispensary customer and Detroiter regarding weed labels. (They asked not to be named because possessing cannabis is still illegal under federal law.) But when it comes to absorbing all that information, they said “it’s a lot to ask.”
Still, because every weed label lists a testing laboratory, it’s possible for consumers to pick a lab they trust and stick to it.
Problems in the testing industry are debated hotly by cannabis enthusiasts online, and some profess a loyalty to one lab or another.
Will testing get better?
Last year’s state budget included $2.8 million to build a state lab to double-check results from the private testing industry. Miller of ACT Laboratories said he hopes that lab, which isn’t yet complete, will help make tests more accurate, no matter which lab they come from.
Once the state lab selects its testing methods, private labs across the state could effectively be forced to adopt the same methods. David Harns, a spokesperson for the state’s Cannabis Regulatory Agency, said the agency hasn’t settled on the new lab’s methods and isn’t commenting on concerns about testing because of ongoing litigation with Viridis.
Welch, of Viridis, agreed that a state lab could bring more consistency to the industry — but only, as he wrote in an email, “if they use AOAC approved methods which the CRA requires labs to follow.”
“If they change the rules, we’ll absolutely be following those,” he added. “I can assure you that the precision is going to be at the same high level as anything we put out.”
Consumers can help improve the system by submitting online complaints if they suspect their cannabis product hasn’t been properly tested.
Those complaints could soon be resolved a bit faster. Gov. Gretchen Whitmer’s budget proposal this year includes an extra $3.4 million for the Cannabis Regulatory Agency to hire nine new staff members with a focus on enforcement and safety inspections.
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