Exposure to Nicotine and Selected Toxicants in Cigarette Smokers Who Switched to Electronic Cigarettes: A Longitudinal Within-Subjects Observational Study

Abstract

Introduction: Electronic cigarettes (e-cigarettes) are purported to deliver nicotine aerosol without any toxic combustion products present in tobacco smoke. In this longitudinal within-subjects observational study, we evaluated the effects of e-cigarettes on nicotine delivery and exposure to selected carcinogens and toxicants. Methods: We measured seven nicotine metabolites and 17 tobacco smoke exposure biomarkers in the urine samples of 20 smokers collected before and after switching to pen-style M201 e-cigarettes for 2 weeks. Biomarkers were metabolites of 13 major carcinogens and toxicants in cigarette smoke: one tobacco-specific nitrosamine (NNK), eight volatile organic compounds (1,3-butadiene, crotonaldehyde, acrolein, benzene, acrylamide, acrylonitrile, ethylene oxide, and propylene oxide), and four polycyclic aromatic hydrocarbons (naphthalene, fluorene, phenanthrene, and pyrene). Changes in urine biomarkers concentration were tested using repeated measures analysis of variance. Results: In total, 45% of participants reported complete abstinence from cigarette smoking at 2 weeks, while 55% reported continued smoking. Levels of total nicotine and some polycyclic aromatic hydrocarbon metabolites did not change after switching from tobacco to e-cigarettes. All other biomarkers significantly decreased after 1 week of using e-cigarettes (p < .05). After 1 week, the greatest percentage reductions in biomarkers levels were observed for metabolites of 1,3-butadiene, benzene, and acrylonitrile. Total NNAL, a metabolite of NNK, declined by 57% and 64% after 1 and 2 weeks, respectively, while 3-hydroxyfluorene levels declined by 46% at week 1, and 34% at week 2. Conclusions: After switching from tobacco to e-cigarettes, nicotine exposure remains unchanged, while exposure to selected carcinogens and toxicants is substantially reduced. Implications: To our knowledge, this is the first study that demonstrates that substituting tobacco cigarettes with an e-cigarette may reduce user exposure to numerous toxicants and carcinogens otherwise present in tobacco cigarettes. Data on reduced exposure to harmful constituents that are present in tobacco cigarettes and e-cigarettes can aid in evaluating e-cigarettes as a potential harm reduction device.

Limited mutagenicity of electronic cigarettes in mouse or human cells in vitro

“…Such inherent shortcoming of the in vitro model systems could be addressed in vivo by inhalation experiments in appropriate animal models [32, 44]. Furthermore, carcinogenic compounds inhaled during vaping undergo biotransformation in human lungs and other tissues and organs to produce DNA reactive species that may lead to mutagenesis [25, 72, 73]. The metabolic capacity of human cells to activate e-cig derived carcinogens in vivo may not be similar to that in vitro by various cell types.…”

“…Data pointing to a carcinogenic effect of e-cig could be used to counter the prevailing perception that e-cig use is healthier than smoking [17–21]. Conversely, if the data show no or less carcinogenic effect of e-cig as compared to tobacco smoke, they could lead to evidence-based promotion of vaping as an alternative nicotine delivery method for tobacco harm reduction [22–25]. …”

A critique of the US Surgeon General’s conclusions regarding e-cigarette use among youth and young adults in the United States of America

“…The Surgeon General acknowledges that e-cigarettes carry far fewer toxins than cigarettes, and so are likely far less hazardous to the user's health. For example, e-cigarette users who do not smoke show far lower urine levels of tobacco smoke toxicants than cigarette smokers [63][64][65]. This section of the report places excessive emphasis on potential absolute risks of e-cigarette use and fails to consider the likelihood that substituting e-cigarettes for conventional cigarettes can prevent much if not all of the harm caused by smoking.…”

Electronic cigarettes—A review of the physiological health effects

“…The thirdhand nicotine (in other words, exposure to nicotine from surface deposits) from ECs was negligible, especially compared with CCs (Bush and Goniewicz 2015). Therefore, both in terms of vaping or secondhand vaping, nicotine levels can be high (especially with newer devices) and similar to CCs (Goniewicz et al 2017). If so, we should expect to see consequences of EC use on important body functions such as the cardiovascular or pulmonary systems.…”

“…Farsalinos et al (2014a) received information from more than 19 000 subjects through an internet survey where 65.4% of respondents with asthma and 75.7% of people with COPD said switching from CCs to ECs improved their symptoms. There is, therefore, some evidence that a switch from CCs to EC may provide some health benefits to users (Van Staden et al 2013;Nutt et al 2014;McRobbie et al 2015;Polosa 2015;Campagna et al 2016;Cibella et al 2016;Goniewicz et al 2017). Interestingly, recent studies suggest that the use of ECs lowers levels of expired nitric oxide (NO) (Vardavas et al 2012;Marini et al 2014; but see Flouris et al 2013).…”