"We don't allow people free access to opioids, for instance, or any prescription drugs," he said
Ned Sharpless, the Acting Commissioner of the FDA, says Given that most e-cigarette users continue to smoke cigarettes, the answer is not clear [that e-cigarettes aid quitting]. A 2015 survey cited by The Truth Initiative (an anti-tobacco organization) found that almost 60% of those who used e-cigarettes also smoked cigarettes, called as dual users

Para-Ethoxybenzaldehyde, Ethyl 10-Undecenoate, Ethyl 2-Methylbutyrate, Ethyl Acetate, Ethyl Acetoacetate, Ethyl Alcohol, Ethyl Benzoate, Ethyl Butyrate, Ethyl Cinnamate, Ethyl Decanoate Fenchol, Ethyl Furoate, Ethyl Heptanoate, Ethyl Hexanoate, Ethyl Isovalerate, Ethyl Lactate, Ethyl Laurate, Ethyl Levulinate, Ethyl Maltol, Ethyl Methyl Phenylglycidate, Ethyl Myristate, Ethyl Nonanoate, Ethyl Octadecanoate, Ethyl Octanoate, Ethyl Oleate, Ethyl Palmitate, Ethyl Phenylacetate, Ethyl Propionate, Ethyl Salicylate, Ethyl trans-2-Butenoate, Ethyl Valerate, Ethyl Vanillin, 2-Ethyl (or Methyl)-(3,5 and 6)-Methoxypyrazine, 2-Ethyl-1-Hexanol, 3-Ethyl -2 -Hydroxy-2-Cyclopenten-1-One, 2-Ethyl-3, (5 or 6)-Dimethylpyrazine, 5-Ethyl-3-Hydroxy-4-Methyl-2(5H)-Furanone, 2-Ethyl-3-Methylpyrazine, 4-Ethylbenzaldehyde, 4-Ethylguaiacol, para-Ethylphenol, 3-Ethylpyridine, Eucalyptol
The risk is substantially increased by exposure even to low levels of tobacco smoke, as with exposure to second-hand smoke