Today the U.S. Centers for Disease Control and Prevention (CDC) finally confirmed that the vast majority of patients with vaping-related respiratory illnesses have reported using cannabis products, typically purchased on the black market. Among 514 patients for whom the information was available, the CDC found, 77 percent reported using THC products. Just 16 percent said they had vaped only nicotine, although the types, sources, and brands of the products were not identified.Since people may be reluctant to admit illegal drug use, the true rate of THC vaping among the patients with respiratory symptoms is almost certainly higher. Prior data from...