Police arrested 2 men in a drug bust in Kenosha, Wisconsin, for manufacturing and selling THC-laced vaping cartridges, an illegal practice that could be driving the lung-related illness linked to vaping, according to the New York Times.Why it matters: State and federal health investigators have not determined the cause of the illness, but their ongoing hypothesis is noxious chemicals finding their way into vaping supplies through illegal manufacturing.Context: State and federal health labs on Sept. 5 announced that they found a common chemical linked to every patient who provided a sample of their marijuana products.The chemical, vitamin E acetate, is not an approved additive for THC vaping liquid in New York.A 17-year-old who was one of the people hospitalized in New York state for the lung illness told the Times that he'd meet people on the street who were selling THC vaping fluid. “I’d meet people at Starbucks, a cross street, in front of an apartment, wherever they tell you,” he said. “It never comes up where they source it. You don’t ask.”Medium-grade THC is expensive, so people illegally add cheap substances to stretch the oil further and turn a larger profit.Police found the 2 men with vaping cartridges labeled with flavors like strawberry and peaches and cream, flavors that President Trump plans to ban as a way to curb the dramatic rise in youth vaping.Go Deeper: 6 dead from vaping-related lung illness