Nicotine is the addictive substance found in tobacco crops. Benzoic acid can also be naturally present in vegetation, and is used commercially in dyes, perfumes, insect repellants, and meals preservatives. Existing cell, animal, and medical studies suggest that glycerin and propylene glycol irritate the lining of the lungs. One small clinical research from 2018 that found that the compounds changed vapers’ sputum—the mucosal lining that covers the internal respiratory tract—to specific different immune proteins. Some of these protein adjustments have been linked to bronchial asthma. Sign up for our Health Tip of the Day publication, and obtain day by day tips that can assist you to reside your healthiest life.