Illegal weed in Arizona has toxins that could make you vomit

Since Arizona legalized recreational marijuana in 2020, buying weed has been easier than ever. All one has to do is walk into one of the many dispensaries that have proliferated in the Valley and beyond, drop some cash and walk out with some bud.

Despite that, there’s still illegal cannabis to be purchased in Arizona. And a new study found that illicit weed might make you sick.

Over a seven-month span from late 2023 to the summer of 2024, a joint task force of the Maricopa County Sheriff’s Office and the U.S. Postal Inspection Service collected 79 samples of unlicensed flower from 37 seizures in Arizona. Researchers at Arizona State University tested the samples for fungal contaminants and mycotoxins.

The researchers found that 16% of tested samples had detectable levels of contaminants that exceeded the “typical regulatory levels in most agricultural commodities,” the study read. That might not seem like much, but the study said using that contaminated weed could cause “opportunistic infection” and lead to recurring vomiting.

Maxwell Leung, one of the study’s authors and a natural science professor at ASU, said that could be particularly risky for immunocompromised people, such as those with cancer or HIV, who often rely on cannabis as a pain reliever.

“That’s going to be dangerous for them,” Leung said.

Illegal weed is still big business nationally. According to a 2023 report by New Frontier Data, an analytics company focused on cannabis, Americans in 2022 bought $76 billion worth of illegal weed and just $46 billion of legal weed. But it’s not clear how big the illicit market is in Arizona. Licensed dispensaries are everywhere, and cannabis customers spent $1.4 billion on legal marijuana in Arizona in 2024. Per the ASU study, 90% of the illegal weed samples seized by authorities during the review period originated in California.

The strains were likely contaminated due to being grown in unhygienic conditions, Leung said. Amid the seizures, the task force identified operations in indoor environments with clear problems of high moisture and water damage. None of these locations, which were often found in residential buildings, were properly designed or managed for plant production, the ASU study read.

Examining photos of some of the illicit grow rooms, Leung found “very poor, unhygienic” working environments, with algae growing on the floor of one greenhouse under troughs of cannabis plants. There were dirty and disorganized workstations, black mold growing on the ceilings, water damage and mold along baseboards and improperly ventilated greenhouse areas.

“This is not a properly run greenhouse, and because of that, more mold will grow,” Leung said. “Because of the poor grow and manufacturing environment, this illegal product is susceptible to contamination.”

By comparison, the Arizona Department of Health Services inspects licensed grow facilities and dispensaries, and legal marijuana is required to be tested for contaminants. For that reason, Leung states what should be obvious: Buying from a licensed dispensary is “generally a safer choice.”