State and federal health authorities are focusing on the role of contaminants or counterfeit substances as a likely cause of vaping-related lung illnesses — now up to 354 possible cases in 29 states, nearly double the number reported to be under investigation last week, The Washington Post has learned.

Officials are narrowing the possible culprits to adulterants in vaping products purported to have THC, the component in marijuana that makes users high, as well as adulterants in nicotine vaping products.

The sudden onset of these mysterious illnesses and the patients’ severe and distinctive symptoms have led investigators to focus on contaminants, rather than standard vaping products that have been in wide use for many years.

The investigation is “starting to point to what solvents are being used, and that can vary a lot” — especially in counterfeit or black-market products, including potentially mislabeled solvents that consumers buy themselves to make do-it-yourself “home brews,” said an official at the Centers for Disease Control and Prevention, which is heading the investigation.

Vaping refers to the increasingly popular practice of inhaling vapor from an e-cigarette device, which frequently involves heating a liquid that can contain nicotine, marijuana or other drugs. Those active ingredients are delivered in solvents. [Read More @ The Washington Post]