State health officials said Friday that many patients sickened with mysterious lung injuries used black market marijuana vaping devices, offering the strongest clues so far into what might be making people sick.

Officials in Wisconsin and Illinois, the states that were the first to report cases, conducted in-depth interviews with 86 patients who said they used a wide range of e-cigarette products. The vast majority reported using illicit products containing THC, the psychoactive component of marijuana. The products were sold as prefilled vape cartridges — tiny disposable containers — and obtained from informal sources, officials said.

Nearly 70 percent of those patients said they used Dank Vapes cartridges, which appear to be predominant 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,” according to a report released by the Centers for Disease Control and Prevention on Friday.

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