Nicotine is the addictive substance found in tobacco vegetation. Benzoic acid can be naturally present in crops, 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 liner of the lungs. One small clinical study from 2018 that found that the compounds changed vapers’ sputum—the mucosal lining that covers the inner respiratory tract—to precise totally different immune proteins. Some of these protein changes have been linked to asthma. Sign up for our Health Tip of the Day publication, and receive daily tips that may assist you to live your healthiest life.