Nicotine is the addictive substance found in tobacco crops. Benzoic acid is also naturally present in plants, 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 medical research from 2018 that found that the compounds changed vapers’ sputum—the mucosal lining that covers the inner respiratory tract—to specific totally different immune proteins. Some of those protein adjustments have been linked to asthma. Sign up for our Health Tip of the Day publication, and obtain daily ideas that may assist you to live your healthiest life.