Nicotine is the addictive substance present in tobacco crops. Benzoic acid can also be naturally found in plants, and is used commercially in dyes, perfumes, insect repellants, and meals preservatives. Existing cell, animal, and clinical research suggest that glycerin and propylene glycol irritate the liner of the lungs. One small clinical research from 2018 that discovered that the compounds modified vapers’ sputum—the mucosal lining that covers the inner respiratory tract—to express totally 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 tips that will assist you to stay your healthiest life.