Nicotine is the addictive substance present in tobacco crops. Benzoic acid can also be naturally present in plants, and is used commercially in dyes, perfumes, insect repellants, and food preservatives. Existing cell, animal, and scientific research recommend that glycerin and propylene glycol irritate the liner of the lungs. One small clinical examine from 2018 that found that the compounds changed vapers’ sputum—the mucosal lining that covers the internal respiratory tract—to specific totally different immune proteins. Some of those protein changes have been linked to asthma. Sign up for our Health Tip of the Day e-newsletter, and obtain daily suggestions that may assist you to reside your healthiest life.