Vaping THC may be behind many of the serious lung diseases that have been tied to e-cigarette use––raising concerns about an increasingly popular way of consuming marijuana, which many consumers view as a relatively safe habit. Up to 450 people have developed illnesses and at least four people have died after using e-cigarettes, Centers for Disease Control and Prevention (CDC) officials said on a call with reporters Friday. While the CDC and Food and Drug Administration (FDA) have not found a device, product or substance that is linked to all cases, a paper published Friday in the New England Journal of Medicine suggests that many sick individuals vaped THC, a compound in marijuana, before developing an illness, either instead of or in addition to nicotine. CDC and public-health officials confirmed this finding. The investigation threatens to shatter many people’s perceptions of marijuana as safe and natural, an opinion that has gained steam as the drug is legalized in more and more states. A 2018 Gallup poll found that Americans largely view both marijuana and e-cigarettes as less harmful than cigarettes, and that more than 40% of respondents thought marijuana was “not too” or ...