A Review on the Safety of Inhalation of Propylene Glycol in E-cigarettes

Abstract

Electronic cigarette (e-cigarette) are being used as a safe alternative to tobacco smoking, or as a smoking cessation device. However, the FDA presumes that e-cigarettes are as hazardous as conventional cigarettes. The Tobacco Control Task Force of the American Association of Public Health Physicians instead has indicated that e-cigarettes closely resemble Nicotine Replacement Therapy products. Since Propylene glycol (PG) constitutes around 89-90% of the e-cigarettes formulation, the objective here is to review the safety of inhalation of PG. All animal and human studies that analyzed the effect of the inhalation of PG have indicated that, PG does not appear to pose a significant hazard via the inhalation route. In fact, in several of these animal studies the concentrations of PG used were higher compared to the concentration used in e-cigarettes and did not give rise to any toxic effects. However, there are no human studies at the level of e-cigarette concentrations.