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E-cigarettes proven safer than traditional cigarettes
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Researchers observed lower levels of selected carcinogens and toxins among former smokers who only used nicotine replacement therapies or e-cigarettes long-term compared to people who had used combustible cigarettes long-term, according to recent findings.
“Although longitudinal cohort studies and randomized, controlled trials will provide the best data to answer questions about the safety and efficacy of e-cigarettes for smoking cessation, these designs are time- and resource-intensive,” Lion Shahab, PhD, from the department of epidemiology and public health at University College London, and colleagues wrote. “In the absence of long-term data, a more pragmatic approach is to compare smokers and former smokers with or without concurrent e-cigarette use in real-life settings.”
To examine the potential risk of long-term e-cigarette use, researchers designed a cross-sectional study in London, England to compare exposure to nicotine, tobacco-related carcinogens and toxins among smokers of combustible cigarettes, e-cigarettes and nicotine replacement therapy (NRT). They divided 181 participants into five groups: combustible cigarette-only users, former smokers who since quitting have used only e-cigarettes or only NRT long-term (6 months or longer) and long-term dual combustible cigarette/e-cigarette or combustible cigarette/NRT users. Shahab and colleagues analyzed participants’ urine and saliva for biomarkers of nicotine, tobacco-specific N-nitrosamines and volatile organic compounds.
The results showed significantly lower metabolite levels for tobacco-specific N-nitrosamines and volatile organic compounds in e-cigarette only and NRT-only users compared with combustible cigarette-only, dual combustible cigarette/e-cigarette or dual combustible cigarette/NRT users. The investigators observed lower levels of the metabolite 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol in e-cigarette-only users compared with all other groups. Among combustible cigarette-only, dual combustible cigarette/NRT and dual combustible cigarette/e-cigarette users, they observed similar levels of tobacco-specific N-nitrosamines and volatile organic compound metabolites.
“Long-term NRT-only or e-cigarette–only use among former smokers is associated with substantially reduced levels of selected carcinogens and toxins compared with combustible cigarette smoking; however, concurrent use of NRTs or e-cigarettes with combustible cigarettes does not seem to offer this benefit,” Shahab and colleagues wrote. “Nicotine delivery of e-cigarettes and NRTs, although variable, is roughly similar to combustible cigarettes, but smaller meaningful differences may exist.” – by Savannah Demko
Disclosure: Shahab reports receiving grants from Cancer Research UK and Pfizer, and personal fees from Atlantis Health Care. Please see the full study for a list of all other author’s relevant financial disclosures.
Perspective
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Frank Leone, MD, MS
Past efforts to understand the risks associated with long-term exposure to electronic cigarette aerosol frequently relied on measuring concentrations of toxicants in the product emission. Dr. Shahab and colleagues take an important next step by reporting on key biomarker concentrations derived in vivo from volunteers endorsing one of four typical exposure patterns. As expected, concentrations of carcinogenic biomarkers were demonstrably lower among people using either nicotine replacement or e-cigarettes when compared to use of their combustible counterparts. While these data are certainly convincing from this important perspective, clinicians should not extend these observations to suggest that e-cigarettes are necessarily safe. The problems may lie within other important perspectives also deserving of consideration.
When interpreting the application of these findings to practice, first keep in mind that absolute serum concentration of nicotine is not relevant to the problem of dependence. Addiction depends both on the rapid delivery of nicotine to the brain, and the timing of exposure relative to periods of high plasticity during brain development. In this case, the risk of e-cigarettes is specific to the nature of the interaction between the device characteristics and the user’s neurobiology. Second, inhaled toxicants may present risks beyond carcinogenesis. High concentrations of propylene glycol and organic flavorants are delivered to the aerodigestive tract, and may have their own important local toxicity profile independent of absorption. Finally, the physical properties of the aerosol itself, such as particle size, temperature, and pH among others, appear to represent a potential source of injury and risk.
While Shahab and colleagues have demonstrated that e-cigarettes have the potential to serve as an important tool for risk reduction, clinicians should demand tight regulation of the variables influencing the global risk profile their patients sustain, and not be seduced by a reduction in carcinogenesis alone.
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