The Center for Disease Control is edging closer to an explanation for vaping-related lung illnesses. The agency has determined that vitamin E acetate, a compound present in all 29 lung tissue samples obtained from patients, is a "potential toxin of concern." The chemical is used to dilute liquid in e-cigarettes and vaping products that include THC, and is found in some food as well as cosmetic products like skin cream. It doesn't normally cause harm when swallowed or rubbed on your skin, but past research suggests that inhaling might impede lung functions.