Nicotine is the addictive substance present in tobacco plants. Benzoic acid can also be naturally found in crops, and is used commercially in dyes, perfumes, insect repellants, and meals preservatives. Existing cell, animal, and medical research counsel that glycerin and propylene glycol irritate the lining of the lungs. One small scientific examine from 2018 that discovered that the compounds changed vapers’ sputum—the mucosal lining that covers the interior respiratory tract—to express totally different immune proteins. Some of those protein modifications have been linked to asthma. Sign up for our Health Tip of the Day newsletter, and receive daily ideas that can allow you to reside your healthiest life.