Nicotine is the addictive substance found in tobacco vegetation. Benzoic acid can be naturally found in plants, and is used commercially in dyes, perfumes, insect repellants, and meals preservatives. Existing cell, animal, and scientific research counsel that glycerin and propylene glycol irritate the lining of the lungs. One small scientific study from 2018 that found that the compounds changed vapers’ sputum—the mucosal lining that covers the inner respiratory tract—to specific completely different immune proteins. Some of those protein adjustments have been linked to asthma. Sign up for our Health Tip of the Day newsletter, and obtain every day suggestions that may help you live your healthiest life.