Several marijuana products have been identified as possible culprits in the mysterious epidemic of serious lung illnesses that has sickened more than 800 people who use vaping devices and e-cigarettes to inhale THC or nicotine, or both.

Health officials said on Friday that the products include THC-filled vaping cartridges labeled “Dank Vapes,” as well as some other illicit brands that people bought from friends or family or on the street.

But officials said Dank Vapes appeared to be a label that THC sellers can slap on any product and is not a specific formulation or a single product. THC is the psychoactive ingredient in marijuana.

“Dank Vapes appears to be the most prominent in a class of largely counterfeit brands, with common packaging that is easily available online and that is used by distributors to market THC-containing cartridges with no obvious centralized production or distribution,” said a report published on Friday by state health officials from Illinois and Wisconsin, and from the federal Centers for Disease Control and Prevention.