Nicotine is the addictive substance present 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 examine 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 these protein changes have been linked to bronchial asthma. Sign up for our Health Tip of the Day publication, and receive daily suggestions that will assist you to reside your healthiest life.