One big question about the booming Silicon Valley e-cigarette startup Juul is whether the company deliberately marketed its products to teens. Juul has said that its sleek vaping devices are intended for adults trying to quit smoking traditional cigarettes — and that its marketing has had little impact on its sales. But a recent study raises some questions. It suggests that Juul’s social-media ads — which were posted across platforms popular with young people including YouTube, Twitter, and Instagram — were a runaway success. Public-health experts, scientists, and the Food and Drug Administration have been targeting vaping companies in recent months after dozens of reports suggested they wer... [Read more]