For example, certain flavour enhancers and smoothing agents are derived from animal products like glycerin (which can come from animal fat) or castoreum (a secretion from beavers, though rare today)
In an advisory issued on 9/24/19, the California Department of Public Health urged everyone to refrain from vaping
Balfour, David, Neal Benowitz, Suzanne Colby, Dorothy Hatsukami, Harold Lando, Scott Leischow, Caryn Lerman, Robin Mermelstein, Raymond Niaura, Kenneth Perkins, Ovide Pomerleau, Nancy Rigotti, Gary Swan, Kenneth Warner, and Robert West
It increases the risk of cancers of the oral cavity and pharynx, larynx, lung, esophagus, pancreas, uterine cervix, kidney, bladder, stomach, colon and rectum and liver, as well as acute myeloid leukemia
The American Cancer Society's website, The Great American Smokeout is a good resource