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Mail Tribune / Jamie Lusch

Marijuana samples are tested at MW Labs, Dr. Wendy Wen's cannabis testing laboratory in Medford.

A look inside a cannabis testing lab

When you get high, you don’t want to get poisoned.

And the only way to make sure you’re not sucking up any toxic pesticides or solvents is to have cannabis tested.

MW Labs, at 724 S. Central Ave., Medford, is one of 22 accredited labs throughout the state that give you the skinny on weed before it’s consumed. If you go to a store and the Dragon OG says it has 30 percent THC, that percentage has been verified by a lab.

Wendy Wen, owner of MW Labs, collects samples from local growers and analyzes them for 59 pesticides as well as THC levels. For cannabis oils, she tests for pesticides, potency and solvents, which are used in the extraction process.

“It took a year for me to establish the method and the assay,” says Wen, who has degrees in chemistry and computer science. “I think that is why there aren’t many people with labs.”

All cannabis sold in stores must be tested, according to regulations established by the Oregon Legislature, the Oregon Liquor Control Commission and the Oregon Health Authority.

OLCC conducted a four-day audit of MW’s procedures and equipment last July. She finally went live with her lab last October and is now able to process 100 samples a day. MW is able to test for pesticides and solvents, which only about half the labs in the state have received accreditation to analyze.

Samples are tested for minute concentrations of pesticides such as pyrethrins, which attack the nervous system of insects. Labs look for concentrations of anywhere from 0.2 parts per million to 2 parts per million, depending on the pesticide.

“Anything over the limit, they fail,” says Wen, who adds she doesn’t consume cannabis products.

The $290 testing package at Wen’s lab looks for pesticides, potency and moisture content. Cannabis oil testing costs $325 and looks for potency, pesticides and residual solvents.

Not only is running a lab complicated, but you’ve got to know how to operate and repair mass spectrometers and other high-tech equipment, including huge canisters of nitrogen that help separate molecules.

Wen’s liquid chromatograph machine ionizes samples with a 4,000-volt blast.

The equipment is expensive, says Wen, who compared the cost of the machines to buying a house.

“It’s not easy to set up a lab,” says Wen, who previously worked in the pharmaceutical industry. “The most critical thing to have is the knowledge.”

Wen previously had a testing lab in Colorado, and she has labs in the South that are used by doctors and hospitals to test patients for opioids.

“My goal is to help the farmers as much as I can, and to educate the public,” says Wen, who moved to the U.S. from China in 1999.

Cannabis testing actually begins in the field. Wen typically goes to a grow site and takes samples to get a good cross-section of a field.

“If you don’t get a representative sample, you don’t get good results,” Wen says.

She typically surveys a field and plots out the plants on a computer to come up with a sampling plan.

All the samples are mixed to come up with an average for the entire field. Even though a particular flower might be labeled 30 percent THC, that amount is based on an average. The actual flower you’re consuming might have higher or lower THC.

Most growers typically pass the testing, Wen says.

When cannabis was first legalized, independent reviews found inconsistent results from lab to lab, and many growers complained about the length of time it took for the labs to test their product.

OLCC spokesman Mark Pettinger says he thinks many of these initial problems have been resolved. The state accreditation program requires standardized testing protocols for labs.

“Before, when we had a bottleneck, we had less than a dozen labs,” Pettinger says. With more labs and more consistent testing protocols, the long lead times have improved markedly, he says.

In addition to the testing for pesticides and solvents, there are other checks that most people don’t know about, he says.

A check for water activity during the drying process is important to keep the plants from getting mold, Pettinger says.

In addition, the moisture content of the dried flower is checked to make sure it doesn’t affect the weight of the product.

The main idea behind the testing is simple.

“We want to ensure quality products that won’t get people sick,” Pettinger says.

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