How we tested legal weed and investigated why some marijuana never makes it to dispensary shelves

Sun-Times reporter Tom Schuba holds up a bag of weed he purchased with reporter Stephanie Zimmermann at a Columbia Care dispensary in Jefferson Park. The sample later passed all tests at a lab. | Brian Ernst / Sun-Times

We started with a simple question: “What’s in your weed?”

To find out, first the Chicago Sun-Times obtained data from the Illinois Department of Agriculture on failed lab test results.

We filed a total of six public records requests under the Illinois Freedom of Information Act that brought thousands of electronic “pages” — all released only as PDF files despite being asked to view electronic records.

Sun-Times reporters entered more than 3,000 rows of results into a spreadsheet to better understand why some weed in Illinois fails state-mandated tests to ensure safety and never makes it to dispensary shelves.

Then, we went shopping.

We bought a total of nine packaged pre-rolled joints, one of the most popular legal weed products, shopping at seven dispensaries in Chicago and the suburbs. We also bought a chunk of cannabis flower at an eighth dispensary.

Reporter Stephanie Zimmermann entering the Columbia Care dispensary in Jefferson Park.

The pre-rolls were grown at cultivation centers owned by these growers: Green Thumb Industries, Verano Holdings, PharmaCann, Ascend Wellness Holdings and Acreage Holdings.

They were purchased at shops operated by some of those companies — GTI’s Rise store in Niles, Verano’s Zen Leaf in Greektown, PharmaCann’s Verilife on the Near North Side and Ascend’s MOCA in Logan Square — as well as from Curaleaf in Skokie, Dispensary 33 in West Town and Cresco Labs’ Sunnyside in River North.

The chunk of cannabis flower was grown by Cresco and sold at Columbia Care in Jefferson Park. We chose that because we wanted to include another large cultivator but couldn’t find any of that company’s weed in a pre-roll.

The flower sample also provided a contrast to the pre-rolls.

Reporters Stephanie Zimmermann and Tom Schuba leaving the Zen Leaf dispensary in Greektown with their purchase.

On the same day we purchased them, we took all of the samples to Origo Labs in Jefferson Park, a state-registered cannabis lab we hired to do the testing. Each sample was identified with a number and letter and carefully placed into sterile containers provided by the lab.

The lab analyzed the samples for potency and conducted quality assurance tests for microbiological contaminants, mycotoxins, heavy metals and 53 pesticides. The tests for mold, yeast and various bacteria involved growing and analyzing the organisms on Petrifilm plates made by 3M.

Reporter Tom Schuba gets ready to bag samples for testing by Origo Labs. Each was identified by number and letter.

Just one of the pre-roll samples and the lone fresh flower sample passed all of the contaminant tests.

Eight of the nine pre-rolls tested above Illinois’ limits for two or more microbiological contaminants. And four failed four different microbiological tests.

None of the samples had any detectable E. coli, salmonella, 53 types of pesticides or mycotoxins, which are toxic compounds produced by certain types of mold.

And none tested above state limits for heavy metals: lead, arsenic, cadmium, mercury or chromium.