Critical Appraisal of Exposure Studies on E-Cigarette Aerosols Generated by High-Powered Devices

The InExpose system manufactured by SCIREQ® is valuable equipment for conducting preclinical studies in the laboratory. It generates e-cigarette (EC) aerosol by puffing the box mod of a high-powered third-generation device (JoyeTech® EVIC Mini), with its atomizer replaced by a custom-made 70 mL tank. We examined the experimental quality of aerosol generation procedures in 40 studies selected from an extensive literature search focused on the usage of the EVIC Mini with a 0.15 Ω coil. Only 14 out of the 40 studies provided sufficient information on their aerosol generation methodology. We identified and reviewed individually 5 studies from the 14 mentioned above that also conducted a chemical analysis of the aerosol. According to our experimental results, there is full certainty that all 14 studies exposed biological systems to aerosols generated under overheating and unrealistic conditions with high aldehyde loads that follow from machine puffing a high-powered device with inappropriate airflow. Given the similarity in design and scope of all studies and the needed training to use the InExpose, we argue that this evaluation very likely applies to the remaining 26 studies that used this equipment without providing sufficient information on aerosol generation procedures. Since preclinical studies are valuable for assessing effects on in vitro and in vivo systems exposed to EC aerosols, it is important to provide full information on aerosol generation parameters and to prevent exposing these biological systems to overheated and toxin-loaded aerosols. Finally, we provide a series of guidelines on aerosol generation procedures that we believe will be useful for the operation of the InExpose and for preclinical studies in general.