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