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There has been little research on the health consequences of e-cigarette use. Currently there is no evidence that short-term e-cigarette use poses serious risks to health; evidence is lacking on long-term effects.

As noted in an earlier section, e-cigarette vapor has been found to contain a number of potentially toxic compounds, but at levels generally far lower than those found in tobacco smoke; these include tobacco-specific nitrosamines (Kim & Shin, 2013), polycyclic aromatic hydrocarbons, formaldehyde, acetaldehyde, and acroleine (Westenberger, 2009; Laugesen et al., 2009; Goniewicz et al., 2012; Burstyn, 2013), fine and ultrafine particulates (Pellegrino et al.,2012), cadmium, lead and nickel (Goniewicz et al., 2013), silicate particles (Williams et al., 2013), cis-N-oxide, trans-N-oxide, myosmine, anatabine and anabasine (Etter et al.,2013). 

The cytotoxicity of e-cigarette refill fluids has been tested in several studies.  Bahl et al. found that the degree of cytotoxicity in embryonic and adult cells was correlated with the number and concentration of chemicals used to flavor fluids, rather than the nicotine content (Bahl et al., 2012).

Romagna et al. (2013) evaluated the cytotoxic potential of 21 e-cigarette liquids compared to the effects of cigarette smoke according to the UNI EN ISO 10993-5 standard, finding e-cigarette vapor to be significantly less cytotoxic compared tobacco cigarette smoke.

Oral health: Mouth and throat irritation are common in e-cigarette users (Etter, 2010) but these symptoms usually wane after several weeks use. They are most likely due to exposure to propylene glycol and glycerol in the vapor (Caponetto et al., 2012).

Cardiovascular health:
Farsalinos et al. (2013) examined the cardiotoxicity of e-cigarette vapor extracts and found that while some samples had cytotoxic properties on cultured cardiomyoblasts, associated with the production process and materials used in flavourings, in all cases the e-cigarette vapor extracts were significantly less cytotoxic than tobacco smoke extract.

When healthy volunteer smokers took 10 puffs of e-cigarettes, Vansickel et al. (2010) found no effects on their heart rate whereas when tobacco cigarettes were smoked, participants’ heart rates increased within 5 minutes of use. Following four weeks of e-cigarette use, the blood pressure recordings of 32 smokers showed no change (Miura et al., 2011).  A single case report of a cardiac arrhythmia in an elderly woman has been published (Monroy et al., 2012) but it is not possible to attribute this event solely to the use of e-cigarettes because of the other co-morbidities in this patient.

Respiratory health: Williams et al. (2013) found evidence of dose-dependent cytotoxicity in human pulmonary fibroblasts exposed to cartomizers obtained from one manufacturer, with cytotoxicity more pronounced when tin particles were present in the fluid.

E-cigarette use may cause a dry cough probably due to exposure to propylene glycol and glycerol in the vapor but this wanes after several weeks use (Caponetto et al., 2012). Acute but clinically insignificant reductions in lung function (reduction in FEV1/FVC) were found in e-cigarette users following a brief session of active e-cigarette smoking and one hour of passive e-cigarette smoking. In contrast, active (indicative: 7.2% reduction in FEV1/FVC; p < 0.001) but not passive (indicative: 3.4% reduction in FEV1/FVC; p = 0.005) tobacco cigarette smoking undermined lung function (Flouris et al., 2013). Vardavas et al. asked healthy smokers without chronic lung disease to inhale from an e-cigarette for 5 minutes; no changes were found in lung function, including spirometry and oscillometry, but the researchers noted clinically non-significant increases in airways resistance and measurable decreases in the fraction of exhaled nitric oxide, similar to those seen shortly after inhaling tobacco smoke (Vardavas et al., 2012; Avdalovic & Murin, 2012). A case report of lipoid pneumonia in a 42 year old woman who used e-cigarettes for seven months has been published (McCauley et al., 2012) but the presence of co-morbidities means attribution to e-cigarette use is inconclusive.

There are no studies of the long-term effects of e-cigarette use to date that would enable a comparison with the well-described adverse effects on lung health from long-term tobacco smoking. No studies have been published of the effects of e-cigarette use on the respiratory function of people with chronic lung disease, which is common in long-term tobacco smokers.

Haematological health:  A study of 32 smokers found no measurable changes in the blood count with use of e-cigarettes daily (more than 150 puffs per day) for four weeks (Miura et al., 2011). In another recent study, no changes in blood count were observed in smokers following 30 minutes using e-cigarettes; nor were changes observed in never-smokers after 30 minutes of passive exposure to e-cigarette vapour (Flouris et al., 2012). In contrast, tobacco smoking increased total white blood cell, lymphocyte and granulocyte counts for at least one hour in smokers and never-smokers alike (Flouris et al., 2012).

Deaths: No deaths directly attributable to e-cigarette use have yet been reported in the medical literature. A single case of death in a young child following ingestion of refill bottle fluid has been reported (but not substantiated).  A recent review of nicotine toxicity suggests the lethal dose of nicotine in adults is not as has been thought (30-60 mg), but rather far higher, in the range of 500-1000 mg of absorbed (not only ingested) nicotine (Mayer, 2013).

In summary, the available data on the health effects of short-term e-cigarettes use suggest serious problems are rare. The data on the health effects of long-term use of e-cigarettes are as yet very limited (Callahan-Lyon, 2014). However, given what is known about tobacco smoking, the effects are unlikely to be as severe.

Avdalovic MV, Murin S. Electronic cigarettes: no such thing as a free lunch...Or puff. Chest. 2012 Jun;141(6):1371-2.

Bahl V, Lin S, Xu N, Davis B, Wang YH, Talbot P. Comparison of electronic cigarette refill fluid cytotoxicity using embryonic and adult models. Reprod Toxicol. 2012 Dec;34(4):529-37.

Burstyn I. Peering through the mist: systematic review of what the chemistry of contaminants in electronic cigarettes tells us about health risks. BMC Public Health. 2014 Jan 9;14(1):18.

Callahan-Lyon P. Electronic cigarettes: human health effects. Tob Control. 2014 May;23 Suppl 2:ii36-ii40.

Caponnetto P, Campagna D, Papale G, Russo C, Polosa R. The emerging phenomenon of electronic cigarettes. Expert Rev Respir Med. 2012 Feb;6(1):63-74.

Etter JF. Electronic cigarettes: a survey of users. BMC Public Health. 2010 May 4;10:231.

Farsalinos KE, Romagna G, Allifranchini E, Ripamonti E, Bocchietto E, Todeschi S, Tsiapras D, Kyrzopoulos S, Voudris V. Comparison of the cytotoxic potential of cigarette smoke and electronic cigarette vapour extract on cultured myocardial cells. Int J Environ Res Public Health. 2013 Oct 16;10(10):5146-62.

Flouris AD, Chorti MS, Poulianiti KP, Jamurtas AZ, Kostikas K, Tzatzarakis MN, Wallace Hayes A, Tsatsakis AM, Koutedakis Y. Acute impact of active and passive electronic cigarette smoking on serum cotinine and lung function. Inhal Toxicol. 2013 Feb;25(2):91-101.

Flouris AD, Poulianiti KP, Chorti MS, Jamurtas AZ, Kouretas D, Owolabi EO, Tzatzarakis MN, Tsatsakis AM, Koutedakis Y. Acute effects of electronic and tobacco cigarette smoking on complete blood count. Food Chem Toxicol. 2012 Oct;50(10):3600-3.

Goniewicz ML, Knysak J, Gawron M, Kosmider L, Sobczak A, Kurek J, Prokopowicz A, Jablonska-Czapla M, Rosik-Dulewska C, Havel C, Jacob P 3rd, Benowitz N. Levels of selected carcinogens and toxicants in vapour from electronic cigarettes. Tob Control. 2014 Mar;23(2):133-9.

Kim HJ, Shin HS. Determination of tobacco-specific nitrosamines in replacement liquids of electronic cigarettes by liquid chromatography-tandem mass spectrometry. J Chromatogr A. 2013 May 24;1291:48-55.

Laugesen M. Safety Report on the Ruyan E-cigarette Cartridge and Inhaled Aerosol. Health New Zealand Ltd. Christchurch, New Zealand, 2008 (accessed 1.2.13).

Mayer B. How much nicotine kills a human? Tracing back the generally accepted lethal dose to dubious self-experiments in the nineteenth century. Arch Toxicol. 2014 Jan;88(1):5-7.

McCauley L, Markin C, Hosmer D. An unexpected consequence of electronic cigarette use. Chest. 2012 Apr;141(4):1110-3.

Miura K, Kikukawa Y, Nakao T, Tokai H, Izumi Y, Fujii H, Taisuke Hojo T. Safety Assessment of Electronic Cigarettes in Smokers. Seikatsu Eisei (Journal of Urban Living and Health Association). 2011;55:59-64.

Monroy AE, Hommel E, Smith ST, Raji M. Paroxysmal atrial fibrillation following electronic cigarette use in an elderly woman. Clinical Geriatrics 2012;20:28-32.

Pellegrino RM, Tinghino B, Mangiaracina G, Marani A, Vitali M, Protano C, Osborn JF, Cattaruzza MS. Electronic cigarettes: an evaluation of exposure to chemicals and fine particulate matter (PM). Ann Ig. 2012 Jul-Aug;24(4):279-88.

Romagna G, Allifranchini E, Bocchietto E, Todeschi S, Esposito M, Farsalinos KE. Cytotoxicity evaluation of electronic cigarette vapor extract on cultured mammalian fibroblasts (ClearStream-LIFE): comparison with tobacco cigarette smoke extract. Inhal Toxicol. 2013 May;25(6):354-61.

Vansickel AR, Cobb CO, Weaver MF, Eissenberg TE. A clinical laboratory model for evaluating the acute effects of electronic "cigarettes": nicotine delivery profile and cardiovascular and subjective effects. Cancer Epidemiol Biomarkers Prev. 2010 Aug;19(8):1945-53.

Vardavas CI, Anagnostopoulos N, Kougias M, Evangelopoulou V, Connolly GN, Behrakis PK. Short-term pulmonary effects of using an electronic cigarette: impact on respiratory flow resistance, impedance, and exhaled nitric oxide. Chest. 2012 Jun;141(6):1400-6.

Westenberger B. Evaluation of e-cigarettes. Rockville, MD: US Food and Drug Administration, Center for Drug Evaluation and Research, Division of Pharmaceutical Analysis; 2009. (accessed 1.2.13)

Williams M, Villarreal A, Bozhilov K, Lin S, Talbot P. Metal and silicate particles including nanoparticles are present in electronic cigarette cartomizer fluid and aerosol. PLoS One. 2013;8(3):e57987. logo
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