School of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Department of General and Inorganic Chemistry, Medical University of Silesia, Sosnowiec, Poland.
Drugs and Addictive Behaviours Research Group, School of Psychology, University of East London, London, UK.
Nicotine Tob Res. 2018 Jul 9;20(8):998-1003. doi: 10.1093/ntr/ntx162.
Article 20 of the European Tobacco Products Directive (EU-TPD) specifies that e-liquids should not contain nicotine in excess of 20 mg/mL, thus many vapers may be compelled to switch to lower concentrations and in so doing, may engage in more intensive puffing. This study aimed to establish whether more intensive puffing produces higher levels of carbonyl compounds in e-cigarette aerosols.
Using the HPLC-UV diode array method, four carbonyl compounds (formaldehyde, acetaldehyde, acetone, and acrolein) were measured in liquids and aerosols from nicotine solutions of 24 and 6 mg/mL. Aerosols were generated using a smoking machine configured to replicate puffing topography data previously obtained from 12 experienced e-cigarette users.
Carbonyl levels in aerosols from the puffing regimen of 6 mg/mL were significantly higher (p < .05 using independent samples t tests) compared with those of 24 mg/mL nicotine. For the 6 and 24 mg/mL nicotine aerosols respectively, means ± SD for formaldehyde levels were 3.41 ± 0.94, and 1.49 ± 0.30 µg per hour (µg/h) of e-cigarette use. Means ± SD for acetaldehyde levels were 2.17 ± 0.36 and 1.04 ± 0.13 µg/h. Means ± SD for acetone levels were 0.73 ± 0.20 and 0.28 ± 0.14 µg/h. Acrolein was not detected.
Higher levels of carbonyls associated with more intensive puffing suggest that vapers switching to lower nicotine concentrations (either due to the EU-TPD implementation or personal choice), may increase their exposure to these compounds. Based on real human puffing topography data, this study suggests that limiting nicotine concentrations to 20 mg/mL may not result in the desired harm minimalization effect.
More intensive puffing regimens associated with the use of low nicotine concentration e-liquids can lead to higher levels of carbonyl generation in the aerosol. Although in need of replication in a larger sample outside a laboratory, this study provides pragmatic empirical data on the potential risks of compensatory puffing behaviors in vapers, and can help to inform future regulatory decisions on nicotine e-liquid concentrations. The cap on nicotine concentration at 20 mg/mL set by the EU-TPD may therefore have the unintended consequence of encouraging use of lower nicotine concentration e-liquid, in turn increasing exposure to carbonyl compounds through compensatory puffing.
欧盟烟草制品指令（EU-TPD）第 20 条规定，电子烟液中尼古丁的含量不得超过 20 毫克/毫升，因此许多电子烟使用者可能被迫选择更低浓度的尼古丁，从而可能会进行更频繁的深吸。本研究旨在确定更频繁的深吸是否会导致电子烟气溶胶中的羰基化合物含量升高。
使用 HPLC-UV 二极管阵列法，测量了 24 和 6 毫克/毫升尼古丁溶液的液体和气溶胶中的四种羰基化合物（甲醛、乙醛、丙酮和丙烯醛）。气溶胶是使用一种吸烟机产生的，该吸烟机的配置可复制先前从 12 名经验丰富的电子烟使用者那里获得的抽吸模式数据。
使用独立样本 t 检验，与 24 毫克/毫升尼古丁相比，6 毫克/毫升尼古丁抽吸方案产生的气溶胶中的羰基化合物水平显著升高（p <.05）。对于 6 和 24 毫克/毫升尼古丁气溶胶，分别为每小时 3.41 ± 0.94 和 1.49 ± 0.30 微克的甲醛水平；2.17 ± 0.36 和 1.04 ± 0.13 微克/小时的乙醛水平；0.73 ± 0.20 和 0.28 ± 0.14 微克/小时的丙酮水平。未检测到丙烯醛。
与更频繁的深吸相关的更高水平的羰基化合物表明，由于欧盟 TPD 的实施或个人选择，转向低尼古丁浓度（要么是由于欧盟 TPD 的实施，要么是个人选择）的电子烟使用者可能会增加他们对这些化合物的暴露。基于真实人类抽吸模式数据，本研究表明，将尼古丁浓度限制在 20 毫克/毫升可能不会达到预期的最小化危害效果。
与使用低尼古丁浓度电子烟液相关的更频繁的深吸会导致气溶胶中羰基化合物的生成水平更高。尽管需要在实验室外的更大样本中进行复制，但本研究提供了关于电子烟使用者补偿性抽吸行为潜在风险的实用经验数据，并有助于为未来关于尼古丁电子烟液浓度的监管决策提供信息。欧盟 TPD 规定的 20 毫克/毫升尼古丁浓度上限可能会产生意想不到的后果，即鼓励使用低尼古丁浓度的电子烟液，从而通过补偿性抽吸增加对羰基化合物的暴露。
