40% THC Flower?! How Lab Shopping and THC Inflation Cheat Cannabis Consumers

Updated: Sep 25, 2019

SAN FRANCISCO—Gold Seal brand co-founder and grower Neil Dellacava’s jaw dropped when he opened the email and saw the note from his lab: the new batch of his award-winning Gold Seal Cherry Cheesecake flower buds was just 17% THC by dry weight?!

Years worth of tests never had it below the mid-20s. He thought he had his licensed commercial indoor grow dialed in!

This was bad.

“It’s the mark of death,” he explained. “If I have something that’s super-fire that’s 19.1[% THC], that’s borderline. If it was 18 or below, buyers try to negotiate the price down.”

Gold Seal ended up firing its cannabis lab over that stinky 17% THC score. Today, Neil’s happy with the consistent, mid-20s they’re getting from their new lab down in Los Angeles. The new batches of Cherry Cheesecake and Red Congolese are most definitely fire.

“Every lab’s numbers are different. Consistency in THC percentage is the most important thing at this point in time for us,” he said. “We know what these strains are capable of. When a grow room has no changes to it whatsoever and gets a lower score, it’s a concern—especially in a world with consumers being number hunters.”

Five years into state-legal medical and adult use cannabis sales in the US, and it’s almost a mandatory business practice for growers and distributors to shop around for the lab that gives them the highest THC scores.

Excessive test result variance between labs—driven in part by THC potency inflation—remains the original sin of the lab industry. The problem varies in size from state to state, but efforts to standardize and monitor labs have been slow in coming.

“It’s a problem for everybody,” said Leafly scientist Nick Jikomes, who authored a damning paper on lab variance published in the journal Nature in 2018.

Problems persist up and down the West Coast:

  • In Washington, lab oversight failure in 2018 preceded lab reporting system collapse this year. Regulators and consumers are “flying blind,” expert Washington data scientist and consultant Jim MacRae told Leafly.

  • In Oregon, THC scores peaked at a ludicrous 40% in January amid a scathing state Oregon Health Authority (OHA) audit that found instances of lab shopping and low lab oversight. “Without a mechanism for verifying test results, Oregon’s marijuana testing program cannot ensure that test results are reliable and products are safe,” the OHA audit concluded.

  • In California, lab shopping appears endemic. At least a couple labs seem to be inflating THC scores, said Josh Wurzer of SC Labs. Other growers and distributors concurred.

A little ratings fraud might seem harmless—like Shell lying about fuel octane ratings, or McDonald’s going light on the quarter-pounder. But the effects are real.

THC inflation punishes craft growers who can’t pay to twist arms for higher THC scores like the big boys. Consumers are skipping great herb. Bunk scores also jeopardize consumers’ ability to take the right amount, increasing their risk of an accident.


“The devastation really sets in when you know it’s a great strain that’s testing less than 15%,” said Ben Grambergu, for DYME distribution in Oakland, California. “At that point you’re almost dead in the water.”

Furthermore, some growers and distributors have gone beyond mere lab shopping for THC.

In an era of tougher-than-organic standards, some have begun shopping for passing pesticide results as well, said Swetha Kaul, chief scientific officer at Cannalysis Labs in Santa Ana, California.

Lab Testing’s Original Sin

THC inflation—lying—might be the original sin of cannabis labs.

Consumers started seeing THC scores next to their cannabis in 2012 during the unregulated medical marijuana era in California. Technicians use mass spectrometry, and gas and liquid chromatography, to detect minute amounts of cannabis’ main active ingredient, THC, and other molecules.

State-licensed lab testing for cannabis purity and potency began in Colorado in 2014. Since its inception, consumers preferred high THC scores. The market signal travels up the supply chain to the stores, distributors, growers, and labs. If a lab starts producing low test scores, growers and distributors can switch to a different lab that consistently offers higher ones.

Who’s to say who is right? Higher lab results can be accurate, or they can be inaccurate due to error, or sometimes, fraud. The science is so new, every lab can legally come up with their own method for arriving at a THC score.

“The truth is, there is no single guidance that works,” states Marc A. Nascarella, PhD, chief toxicologist at MDPH, and a contributor to the Association of Public Health Labs cannabis guidance stated in 2017. “Cannabis is now being put into oils, resins, food products, suppositories, tinctures, creams, lotions, vape pens and, of course, cigarettes. It is much more than dry flower/plant testing.”

“How the scientist interprets the output and reports the results is up to them,” the OHA 2019 audit states.

Labs are subject to varying levels of accreditation, too. California mandates all labs be ISO certified by end of 2019, but not all are yet. Oregon and Washington do not require ISO certification. Instead, both states hired outside vendors to accredit—not license—labs. The Washington State Liquor and Cannabis Board (WSLCB) doesn’t have a single chemist. Instead, their vendor, RJ Lee, has accredited 13 labs.

California’s Emerging Issues

Lab shopping and THC inflation have dogged California’s market since 2012, but testing quality is looking up in the world’s biggest legal market, whereregulators are on the prowl.

Lab numbers will vary by about 3 to 5% THC between labs, growers report. That’s enough to make or break a product launch. (By contrast, a 20% flower that tests between 19 and 21 would be considered a normal variance for the mainstream lab industry, Kaul said.)

“We work with every single lab in the state and we get different results from all of them,” said Christina Dipaci, CEO of The Weed Brand and Paradiso, during the 2018 harvest.

DYME distribution of Oakland said they are choosing not to lab shop right now, even though it may be costing them.

“There are labs we could send our product to and get a higher test result and get a better chance of passing,” said Grambergu. “And can you tell me who is doing it right?”

Josh Wurzer, founder of SC Labs, said customers have switched away from SC after shopping for higher numbers.

“We certainly have clients that are comparing our cannabinoid results against other labs and telling us straight up that they’re making decisions based on cannabinoid results,” he said.

“We have seen one to two labs that are definitely, in comparison to other labs, pumping out really high THC results,” he said.

Kaul, chief scientific officer at Cannanalysis, has seen it, too. “They don’t outright say it, but there’s a lot of times where that’s the understanding.”

Smaller labs may be more subject to pressure, she said. “I’m OK walking away from clients, but if you’re a small startup lab with one client that threatened to walk away, I wouldn’t be surprised.”

Still ‘Flying Blind’ in Washington

Washington is in the process of revoking testing oversight from the state’s Liquor and Cannabis Board. This comes after private citizens busted the state’s biggest lab, Peak Analytics, for inflating THC scores. Straight Line Analytics founder MacRae and others found anomalies in Peak’s state reporting data. For example, Peak tested a Blue Dream flower at 37.1% THC—a statistical near-impossibility.

Peak subsequently failed auditing for microbial testing, the WSLCBsuspended their license, and the lab closed. But there’s nothing in Washington’s rules to stop a disgraced lab operator from reopening. Several have.

Plus, a state system update to increase monitoring this summer achieved the opposite, watchers say. The tracking system is down due to bugs in the code.

“Those with oversight of the market are flying blind,” said MacRae. “Consumers in Washington, for the past 18-plus months, have simply ha