Nicotine is the addictive substance found 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 liner of the lungs. One small medical examine from 2018 that found that the compounds modified vapers’ sputum—the mucosal lining that covers the internal respiratory tract—to specific totally different immune proteins. Some of those protein modifications have been linked to bronchial asthma. Sign up for our Health Tip of the Day newsletter, and receive every day suggestions that can allow you to stay your healthiest life.