Nicotine is the addictive substance found in tobacco plants. Benzoic acid can be naturally present in vegetation, and is used commercially in dyes, perfumes, insect repellants, and meals preservatives. Existing cell, animal, and clinical studies counsel that glycerin and propylene glycol irritate the lining of the lungs. One small medical research 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 these protein adjustments have been linked to bronchial asthma. Sign up for our Health Tip of the Day e-newsletter, and receive daily tips that can help you live your healthiest life.