Summaries
Goel, Reema et al. 2015. Highly Reactive Free Radicals in Electronic Cigarette Aerosols. Chemical Research in Toxicology 28:9 (1675-1677).
In this reported scientific study, a group of researchers from the Pennsylvania State University investigated whether the aerosol produced by an e-cigarette contains reactive, short-lived free radicals. Initially, the researchers proposed that the e-cigarette vapor may contain high concentrations of free radicals, presumably from the presence of high concentrations of free radicals from conventional cigarette smoke. It must be pointed out that reactive, short-lived free radicals, such as reactive oxygen species and reactive nitrogen species, are potentially toxic to organisms, including humans. To be specific, reactive free radicals result to oxidative stress that can damage cellular pathways, such as cell metabolism, proliferation, survival, and inflammation. More notably, oxidative stress due to reactive free radicals is linked – and may be a major factor – in the development of cancer, pulmonary, and cardiovascular diseases induced by smoking. Indeed, the researchers found high concentrations of free radicals in e-cigarette aerosol. In the experiment, the researchers used different eliquids and produced aerosol using a commercially available e-cigarette and solvents. The puff generation was simulated with concentration based on average human usage: 9-second puff duration, 20-second puff interval, 500 mL/min flow rate, and 40 puffs per experiment. The generated aerosol traveled through two impingers where a spin-reagent trap phenyl-N-tert-butylnitrone (PBN) submerged in a benzene solution. Using electron paramagnetic resonance (EPR), the PBN-radical adducts were investigated. The analysis of the data suggested the presence of high concentration of free radicals (2.5 x 1013 to 10.3 x 1013 radicals/puff at 3.3 V) in the aerosol produced by the three different eliquids. Moreover, the researchers tested whether the solvents (propylene glycol and glycerol) and dry puffing may produce free radicals, which were found to be the case. The researchers conclude that the generation of free radicals from smoking e-cigarettes poses a potential toxicological health issue to the smokers.
Yu, Vicky et al. 2016. Electronic cigarettes induce DNA strand breaks and cell death independently of nicotine in cell lines. Oral Oncology 52 (58-65).
Similarly, the study performed by Vicky Yu et al. adds to the growing consensus that e-cigarette smoking is as potentially detrimental to health relative to conventional smoking. In their study, they investigated the effect of exposing head and neck squamous cell carcinoma (HNSCC) and normal epithelial cells to e-cigarette vapor. Three cell lines were cultured for the study: HaCaT, UMSCC10B and HN30. Different cell cultures were exposed to different treatments of e-cigarette vapor (with and without nicotine) and cigarette smoke. The analysis of data suggested that DNA damage is elevated by up to 1.5-fold after exposure to e-cigarette vapor. Moreover, DNA damage is sufficiently induced regardless of whether the liquid contains nicotine or no nicotine. Furthermore, it was found that exposure to e-cigarette vapor also induces DNA double-strand breaks, which is more health threatening. Similarly, the three cell lines were also found to have increased apoptosis and necrosis, regardless of whether the aerosol is nicotine-free or nicotine-containing. Finally, the researchers found that exposure to e-cigarette vapor decreases cell survivability with increasing doses. In general, all results from nicotine-containing vapor were found to have greater values than nicotine-free vapor. To conclude, the researchers strongly agree that e-cigarette smoking is not as safe as advertised by marketing strategies.
Discussion
After reading the scientific articles related to e-cigarette smoking, I agree that smoking e-cigarette is falsely advertised as safer than conventional cigarette smoking. Note that a scientific claim is considered more credible if there is a consensus within the scientific community. In this case, the three scientific particles present substantial evidence against the safety of e-cigarette smoking.
According to the recently reported scientific article, smoking e-cigarette can lower immune system and increase the virulence of MRSA (Hwang et al. 667). In fact, the scientific community has recognized that smoking e-cigarette is not safe, as opposed to advertised by marketing strategies. To point out, the scientific studies performed by Yu et al. and Goel et al. presented substantial evidence suggesting that health problems may result from smoking e-cigarette. In particular, increased DNA damage is present to epithelial and HNSCC cell lines after exposure to e-cigarette regardless of whether the smoke contains nicotine or not (Yu et al. 65). Similarly, e-cigarette aerosol is found to have high concentration of reactive free radicals, which can be toxic to humans depending on dosage (Goel et al. 1677).
In conclusion, e-cigarette smoking is not safe according to the results of the three studies. In particular, e-cigarette smoking affects the immune system and increase DNA damage. Moreover, the aerosol from e-cigarettes contains large amounts of free radicals, which are toxic to humans. With these health issues, the public should be properly informed, and to support public information, I have prepared headlines for two popular media articles. For an honest representation of the scientific findings, this headline can be used: "Nicotine and nicotine-free e-cigarette aerosol elevates DNA breakage and DSB." And for a sensationalized representation of the scientific findings, this headline can be used: "E-cigarette smoke contains toxic chemicals."
References:
Goel, Reema et al. “Highly Reactive Free Radicals in Electronic Cigarette Aerosols.” Chemical Research in Toxicology 28.9 (2015): 1675-1677. Web. 15 July 2016.
Hwang, John H. et al. “Electronic cigarette inhalation alters innate immunity and airway cytokines while increasing the virulence of colonizing bacteria.” Journal of Molecular Medicine 94.6 (2016): 667-679. Web. 2 July 2016.
Yu, Vicky. et al. “Electronic cigarettes induce DNA strand breaks and cell death independently of nicotine in cell lines.” Oral Oncology 52 (2016): 58-65. Web. 15 July 2016.
