Department of Food Science, College of Agricultural Sciences, Pennsylvania State University , University Park, Pennsylvania 16802, United States.
Department of Public Health Sciences, Pennsylvania State University Tobacco Center of Regulatory Science (TCORS), Pennsylvania State University College of Medicine , Hershey, Pennsylvania 17033, United States.
Chem Res Toxicol. 2018 Jan 16;31(1):4-12. doi: 10.1021/acs.chemrestox.7b00116. Epub 2017 Dec 8.
The ever-evolving market of electronic cigarettes (e-cigarettes) presents a challenge for analyzing and characterizing the harmful products they can produce. Earlier we reported that e-cigarette aerosols can deliver high levels of reactive free radicals; however, there are few data characterizing the production of these potentially harmful oxidants. Thus, we have performed a detailed analysis of the different parameters affecting the production of free radical by e-cigarettes. Using a temperature-controlled e-cigarette device and a novel mechanism for reliably simulating e-cigarette usage conditions, including coil activation and puff flow, we analyzed the effects of temperature, wattage, and e-liquid solvent composition of propylene glycol (PG) and glycerol (GLY) on radical production. Free radicals in e-cigarette aerosols were spin-trapped and analyzed using electron paramagnetic resonance. Free radical production increased in a temperature-dependent manner, showing a nearly 2-fold increase between 100 and 300 °C under constant-temperature conditions. Free radical production under constant wattage showed an even greater increase when going from 10 to 50 W due, in part, to higher coil temperatures compared to constant-temperature conditions. The e-liquid PG content also heavily influenced free radical production, showing a nearly 3-fold increase upon comparison of ratios of 0:100 (PG:GLY) and 100:0 (PG:GLY). Increases in PG content were also associated with increases in aerosol-induced oxidation of biologically relevant lipids. These results demonstrate that the production of reactive free radicals in e-cigarette aerosols is highly solvent dependent and increases with an increase in temperature. Radical production was somewhat dependent on aerosol production at higher temperatures; however, disproportionately high levels of free radicals were observed at ≥100 °C despite limited aerosol production. Overall, these findings suggest that e-cigarettes can be designed to minimize exposure to these potentially harmful products.
电子烟市场不断发展，给分析和描述其产生的有害产品带来了挑战。我们之前曾报道过，电子烟气溶胶可以产生高水平的活性自由基；然而，目前只有少数数据可以描述这些潜在有害氧化剂的产生情况。因此，我们对影响电子烟产生自由基的不同参数进行了详细分析。我们使用了温度控制的电子烟设备和一种新颖的机制，可靠地模拟了电子烟的使用条件，包括线圈激活和抽吸气流，分析了温度、功率和电子烟液中丙二醇（PG）和甘油（GLY）溶剂组成对自由基产生的影响。电子烟气溶胶中的自由基通过电子顺磁共振进行自旋捕获和分析。自由基的产生呈温度依赖性增加，在恒温条件下，温度从 100°C 增加到 300°C 时，几乎增加了两倍。在恒定功率下，自由基的产生增加幅度更大，从 10 W 增加到 50 W 时，由于与恒温条件相比线圈温度更高，增加了近两倍。电子烟液 PG 含量也对自由基的产生有很大影响，PG:GLY 比例从 0:100 增加到 100:0 时，自由基的产生几乎增加了三倍。PG 含量的增加也与生物相关脂质的气溶胶诱导氧化增加有关。这些结果表明，电子烟气溶胶中活性自由基的产生高度依赖溶剂，并随温度升高而增加。在较高温度下，自由基的产生在一定程度上取决于气溶胶的产生；然而，尽管气溶胶的产生有限，但仍观察到≥100°C 时自由基水平异常高。总的来说，这些发现表明可以设计电子烟来尽量减少这些潜在有害产品的暴露。
