At least a dozen people have died of an acute lung condition related to vaping, and while officials aren’t ready to pin it on any one chemical or brand, they are warning that many of the patients reported buying THC cartridges from “informal sources” — which is to say off the street or online.

“The vast majority of patients received their products on the streets from friends or dealers,” said Dr. Jennifer Layden, chief epidemiologist for the Illinois Department of Health, in a press call today.

Unfortunately this also resulted in a huge variety of brand names and types of cartridges and devices. “Among all 86 patients in our study, 234 unique e-cigarette or vaping products across 87 different brands were reported,” Layden said. THC products were reported by more than three-quarters of those surveyed, with only 16% of patients saying they used only nicotine cartridges.

The most common brand name, which two-thirds of the patients surveyed reported using, was “Dank Vapes.” While testing of products with this brand name has not yet been carried out, it’s probably safest to avoid them for now. Studies have shown that even popular brands like Juul don’t know exactly what chemicals are produced when these substances are vaporized. And an NBC News-commissioned study[1] showed that many off-brand cartridges contained pesticides that could form hydrogen cyanide when heated.

“We do not know yet what exactly is making people sick,” emphasized Dr. Anne Schuchat, principal deputy director of the CDC. “For example, whether solvents or adulterants are leading to lung injury or whether cases stem from a single supplier or multiple ones. Because of the variety of chemicals that are present in e-cigarettes or vaping liquids and may be added to e-cigarettes or vaping liquid as...

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