Nicotine is the addictive substance present in tobacco vegetation. Benzoic acid can also be naturally found in crops, and is used commercially in dyes, perfumes, insect repellants, and food preservatives. Existing cell, animal, and scientific studies suggest that glycerin and propylene glycol irritate the lining 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 completely different immune proteins. Some of these protein adjustments have been linked to asthma. Sign up for our Health Tip of the Day newsletter, and receive day by day ideas that can assist you to reside your healthiest life.