Nicotine is the addictive substance present in tobacco plants. Benzoic acid can also be naturally found in plants, and is used commercially in dyes, perfumes, insect repellants, and food preservatives. Existing cell, animal, and clinical studies counsel that glycerin and propylene glycol irritate the liner 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 precise totally different immune proteins. Some of these protein changes have been linked to bronchial asthma. Sign up for our Health Tip of the Day newsletter, and receive day by day tips that can assist you to stay your healthiest life.