Nicotine is the addictive substance found in tobacco vegetation. Benzoic acid can be naturally present in vegetation, and is used commercially in dyes, perfumes, insect repellants, and food preservatives. Existing cell, animal, and medical research suggest that glycerin and propylene glycol irritate the liner of the lungs. One small scientific research from 2018 that found that the compounds modified vapers’ sputum—the mucosal lining that covers the internal respiratory tract—to express totally different immune proteins. Some of those protein changes have been linked to asthma. Sign up for our Health Tip of the Day publication, and obtain every day ideas that can assist you to stay your healthiest life.