Nicotine is the addictive substance found in tobacco crops. Benzoic acid can be naturally found in vegetation, and is used commercially in dyes, perfumes, insect repellants, and meals preservatives. Existing cell, animal, and scientific studies counsel that glycerin and propylene glycol irritate the lining of the lungs. One small clinical research from 2018 that found that the compounds modified vapers’ sputum—the mucosal lining that covers the interior respiratory tract—to specific completely different immune proteins. Some of those protein modifications have been linked to asthma. Sign up for our Health Tip of the Day e-newsletter, and receive day by day ideas that will help you reside your healthiest life.