The issue here isnt so much the study type, but the way you ask the question
Our study highlights the hidden risk of these new and popular disposable electronic cigarettes with hazardous levels of neurotoxic lead and carcinogenic nickel and antimony which stresses the need for urgency in enforcement, said senior author Brett Poulin, an assistant professor in the UC Davis Department of Environmental Toxicology
As if premature aging, increased risk of cancer and stroke, yellow teeth, bad breath, and shortness of breath werent enough, if you still smoke, say goodbye to your sense of smell
[165] The survey also found 2.6% regular e-cigarette users used no flavors
Nicotine reduces the protective coating of the stomach while increasing the amount of acid the organ produces