State of the Art Review

Electronic Cigarettes: A Primer

for Clinicians
Hayley Born1, Michael Persky, MD1, Dennis H. Kraus, MD2,
Robert Peng, MD1, Milan R. Amin, MD1, and Ryan C. Branski, PhD1

No sponsorships or competing interests have been disclosed for this article.

Abstract
Objective. To introduce the otolaryngology community to
the current state of research regarding electronic cigarettes,
with special attention paid to mechanism, impact on health
and addiction, and use in smoking cessation.
Data Sources. Review of Google Scholar and PubMed databases using the keywords electronic cigarettes, e-cigs, e-cigarettes,
and vaping. In addition, information from media sources as well
as news outlets was evaluated to gauge public perception of
research findings.
Review Methods. Recent research and randomized controlled
trials were prioritized.
Conclusions. The landscape of electronic cigarette devices is
evolving, as is the research regarding their risks and benefits.
Utilization is rapidly increasing. It appears that older users
employ them as a smoking cessation tool compared to
younger users. The data are generally inconclusive regarding
the benefits of electronic cigarettes for smoking cessation
compared with other methods. Furthermore, the safety
profile of electronic cigarettes is dynamic and difficult to
fully ascertain.
Implications for Practice. Patients with a variety of otolaryngologic conditions, including cancer, may benefit from frank
discussion regarding electronic cigarettes. Furthermore,
increasing patient inquiries regarding these devices are likely
given their increasing popularity.

Keywords
ecigarettes, ecigs, electronic cigarettes, nicotine, vaping
Received July 1, 2014; revised March 3, 2015; accepted April 16, 2015.

tolaryngologists and head and neck surgeons spend

much of their time managing patients with
smoking-related diseaseincluding but not limited
to cancers of the head and neck; sinonasal, laryngeal, and
pharyngeal disorders; and perioperative wound-healing
deficitsas well as those patients requiring smoking

Otolaryngology
Head and Neck Surgery
110
American Academy of
OtolaryngologyHead and Neck
Surgery Foundation 2015
Reprints and permission:
sagepub.com/journalsPermissions.nav
DOI: 10.1177/0194599815585752
http://otojournal.org

cessation counseling. Many smokers now use electronic cigarettes (ECs) to augment or cease their smoking habits.
Electronic cigarettes were first developed in China in 2003
and introduced to the US market in 2007.1 The earlier generations of ECs were accompanied by marketing dedicated to
their supposed health benefits, claiming they were healthier
and less expensive than conventional cigarettes. More brands
emerged and subsequently distanced themselves from this
strategy, decreasing comparisons to conventional cigarettes
and placing more of an emphasis on increased flavor options.2
The EC industry is growing significantly; according to a 2014
study, 466 brands and 7764 unique flavors were identified.2
Between May 2012 and January 2014, a net increase of 10.5
brands and 242 flavors were reported per month.2 For the past
decade, the industry primarily consisted of small purveyors of
ECs; it has since grown and now includes large tobacco companies such as Altria Group, Reynolds-American, and
Lorillard.3 The industry reported an estimated $2 billion in
retail sales in 2013 and is expected to exceed $10 billion by
2017.4 In addition, EC awareness among adults has increased
from 16% in 20095 to 75% in 20126 and, most recently, to
86% in 2013.7 Moreover, the percentage of adults in the
United States who tried ECs at least once increased from 0.6%
in 2009 to 2.7% in 20105 and, most recently, to 8.1% in
2013.6 Of particular concern is that similar trends are observed
among youth. According to a report by the US Centers for
Disease Control and Prevention, more than 263,000 youths in
grades 6 to 12 tried ECs in 2013, a 3-fold increase from
2011.8
This review attempts to update the community regarding
ECs and the rapidly growing user population. Furthermore,
a review of research surrounding their benefits as a smoking
cessation tool and the risks related to addiction and cancer
are included. We hypothesize that there is still inconsequential evidence regarding the recommendation of ECs as a
1
NYU Voice Center, Department of OtolaryngologyHead and Neck
Surgery, New York University School of Medicine, New York, New York,
USA
2
New York Head and Neck Institute North Shore-LIJ Health System, New
York, New York, USA

Corresponding Author:
Ryan C. Branski, PhD, NYU Voice Center, 345 East 37th St, Suite 306, New
York, NY 10016, USA.
Email: ryan.branski@nyumc.org

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OtolaryngologyHead and Neck Surgery

smoking cessation aid. In addition, further investigation is

likely necessary to elucidate the risks of addiction and
cancer with the use of ECs. Nonetheless, with this evergrowing industry and increase in both awareness and use in
patients of all ages, it is necessary for physicians to stay
abreast of the evolving research regarding ECs. This information may be employed to better counsel patients regarding the benefits and risks of ECs.

Methods
A review of the literature was performed by a single
researcher. The search terms electronic cigarettes, e-cigs,
e-cigarettes, and vaping were employed in PubMed to
identify scientific manuscripts. Newer research and randomized controlled trials were prioritized. The most recent
search was conducted on September 19, 2014. The initial
search identified 846 original articles. Articles were excluded
if they met the following exclusion criteria: not related to
electronic cigarettes (n = 334), not written in English (n =
28), opinion or commentary articles (n = 103), review articles
(n = 60), and not directly relevant, such as articles on EC
marketing or the effects of ECs on mental health (n = 280).
Articles were included in the current review study if they presented original scientific data regarding EC users, safety, and
use of ECs as smoking cessation tools. In addition, Google
was used to search for popular media sources (eg, New York
Times and National Public Radio) that reported on government regulation of EC use and lay perception of both safety
and use. Popular media sources were included only if they
met the above criteria and were published within a year of
our initial search; media sources were excluded if they were
not related to EC use, safety, and regulation. Our combined
search resulted in 48 articles forming the basis for this manuscript, with 31 articles containing original data, an additional
10 articles being cited for content, and 7 articles from popular
news outlets. The types of scientific articles included in this
review were surveys, randomized controlled trials, clinical
studies, laboratory analyses, and mathematical analyses. For
the studies that disclosed a funding source, the majority
reported receiving funds from the National Institutes of
Health (NIH) or similar governmental agency. Of note, 1
study was funded by an EC company and another from advocates of smoke-free alternatives. A complete description of
the publication year, author, study design, and funding source
is presented in Table 1. In addition, a PRISMA (Preferred
Reporting Items for Systematic Reviews and Meta-Analyses)
flow diagram describing how we conducted our review is
presented in Figure 1.

What Are Electronic Cigarettes?

The electronic cigarette, or e-cigarette, is a nicotine delivery
device considered by some to be a nicotine replacement
therapy product (such as nicotine gum or patch).9 The
device consists of a battery that applies current to an atomizer where the liquid is stored and aerosolized; this liquid
usually contains nicotine. Several generations of ECs have
evolved; the newest allows for customization of appearance,

energy applied, and liquid content. First-generation ECs

were designed to look and feel like cigarettes (eg, the tip
would brighten with inhalation); however, many newer
models do not resemble cigarettes. They can be disposable
or have rechargeable batteries and/or replaceable liquid cartridges.10 Common designs of ECs, including both disposable and rechargeable models, are presented in Figure 2.
The liquid contained in ECs consists of propylene glycol,
glycerol, distilled water, flavorings, and nicotine. Propylene
glycol and glycerol are used in many food and pharmaceutical
preparations and are generally recognized to be safe for consumption by the Food and Drug Administration (FDA).11 With
regard to the nicotine content or suspected toxins in ECs,
laboratory analyses typically employ techniques such as gas
chromatography (GC), gas chromatographymass spectrometry
(GC-MS), high-performance liquid chromatography (HPLC),
or a combination of these techniques. Interestingly, to date, it
is nearly impossible to generate vapor from ECs in standard
laboratory conditions developed previously for the testing of
conventional cigarettes.12
Nicotine content varies widely among products, typically
ranging from 0 to 34 mg/mL,13 but recent studies found discrepancies between labeled and measured nicotine concentrations.14 In addition, some liquids claim to be free of
nicotine, although trace amounts were identified.12,15 In the
absence of quality standards, EC product consistency
remains a significant concern as product labeling is inconsistent and potentially misleading. Although these liquids
are not regulated, the risk of nicotine toxicity from ECs,
according to a single study, remains low. Variation between
nicotine concentrations in vapor within a particular brand is
also low, although the level of nicotine in the vapor is not
highly correlated with the concentration in the EC liquid.14
Analysis of the liquid and subsequent vapor produced by
ECs confirmed the presence of toxins or suspected toxins.16
A subsequent study, however, showed that the toxins were
present in amounts 9- to 450-fold less than those found in
conventional cigarettes and likely posed minimal health
risk.12 In fact, a comprehensive review compared the levels
of contaminates found in ECs to be acceptable involuntary
workplace exposure levels. The concentrations in ECs were
well below those considered dangerous. The contaminates,
many which are known carcinogens, included polycyclic
aromatic hydrocarbons, tobacco-specific nitrosamines, volatile organic compounds, and inorganic compounds. The
study concluded that only propylene glycol and glycerol
reached levels warranting further attention and regulation
for health-related issues.17 Although exposure is not known
to cause health problems, the magnitude of exposure is
novel and thus warrants further investigation.

Who Is Using ECs?

In 2013, it was estimated that approximately 8% of adults
in the United States had tried ECs, and this number is rapidly rising, increasing from approximately 2.7% in
2010.6,18,19 On the whole, however, most EC users are current smokers; 2 to 8 times more EC users also use

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Born et al

Table 1. Description of Studies Included in Current Review, Including the Source of Funding When Disclosed.
Type of Study/
Publication

Year

First Author

Funding Source

2011

Foulds1

Survey (n = 104)

2014

Zhu2

Comprehensive
Internet search

2013

Regan5

Survey (n =
10,328)

2013

Zhu6

Survey (n =
10,041)

National Cancer Institute

2014

Pepper7

Survey (n =
17,522)

National Cancer Institute and UNC

Lineberger Cancer Control Education
Program

2015

Bunnell8

Analysis of national
youth survey (n =
61,930)

2014

Dawkins10

Repeated measures
(n = 14)

2006

FDA11

FDA database
analysis

2014

Goniewicz13

Laboratory analysis

UK Medicine and Health Products

Regulatory Agency

2014

Goniewicz13

Laboratory analysis

Ministry of Science and Higher Education

of Poland

2014

FDA16

Laboratory analysis

National Cancer Institute of the National

Institutes of Health under the State and
Community Tobacco Control Initiative

Sky Cig, Ltd

Summary of Findings
78% of experienced EC users were
without tobacco use in the prior 30
days.
Older brands tended to focus on the
advantage of ECs over conventional
cigarettes, whereas newer brands
focused on providing new flavors and
product versatility.
EC awareness increased 2-fold between
2008 and 2010, and ever use of ECs has
more than quadrupled between 2009
and 2010; current tobacco users were
most likely to try ECs but did not say
they planned to quit smoking more
often than those smokers who had
never tried ECs.
75.4% reported hearing about ECs, 8.1%
had tried ECs, and 1.4% were current
users; among current smokers, 32.2%
had tried ECs, and 6.8% were current
users.
86% had heard about ECs; current and
former smokers were more likely to be
aware of ECs than nonsmokers.
The number of never-smoking youth who
used ECs increased 3-fold from between
2011 and 2013; intention to smoke
conventional cigarettes was 43.9%
among ever EC users and 21.5% among
never users (adjusted OR, 1.70; 95% CI,
1.24-2.32).
Blood plasma nicotine levels rose
significantly after acute EC use; tobaccorelated withdrawal symptoms and urge
to smoke were significantly reduced.
Database of Select Committee on
Generally Recognized as Safe Substances
Reviews
None of the tested EC products
produced vapor nicotine concentrations
as high as conventional cigarettes;
variation in vapor nicotine
concentrations was low and not related
to the concentration in EC liquid.
EC vapors contained some toxic
substances; the levels of the toxicants
were 9 to 450 times lower than in
cigarette smoke and were, in many
cases, comparable with trace amounts
found in the reference product.
EC products and components contained
detectable levels of known carcinogens
(continued)

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Table 1. (continued)
Year

First Author

Type of Study/
Publication

Funding Source

2014

Burstyn17

Mathematical
analysis

The Consumer Advocates for Smoke-free

Alternatives Association Research Fund

2012

McMillen18

Cross-sectional
survey (n = 3240)

American Academy of Pediatrics Julius B.

Richmond Center for Excellence and
the Flight Attendant Medical Research
Institute and Legacy

2013

King19

National;
consumer-based
survey (n =
10,739)

Supported in part by an appointment to

the Research Participation Program at
the Centers for Disease Control and
Prevention administered by the Oak
Ridge Institute for Science and Education

2010

Etter22

Internet survey
(n = 81)

2011

Etter23

Internet survey
(n = 3587)

2014

Etter24

Swiss Tobacco Prevention Fund

2013

Dawkins25

Longitudinal
Internet survey
(n = 477)
Internet survey
(n = 1349)

2010

Vansickel26

Clinical withinsubject study

(n = 32)

US National Cancer Institute and US

Public Health Services Home

2013

Bullen27

Health Research Council of New Zealand

2013

Caponnetto28

Randomized
controlled
superiority trial
(n = 657)
Prospective
randomized
controlled trial

Lega Italiana AntiFumo

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Summary of Findings
and toxic chemicals; low levels of
nicotine were found in those labeled
with no nicotine; nicotine levels from
the the same EC product varied per puff.
No evidence of potential for exposure of
EC users to contaminants associated with
risk to health at a level that would
warrant attention if it were an involuntary
workplace exposure was observed.
Daily smokers (25.1%) and nondaily
smokers (34.9%) were the most likely to
have tried at least one emerging tobacco
product, compared with former
smokers (17.2%) and never smokers
(7.7%), P \.001.
Awareness and ever use of ECs increased
among US adults between 2010 and
2011; ever use of ECs was higher among
current smokers compared with both
former and never smokers.
ECs were used to quit smoking or
because they were perceived to be less
toxic than tobacco; respondents
reported that ECs may be useful for
smoking cessation.
Most of the respondents were former
smokers who reported that ECs helped
them to quit or reduce their smoking.
ECs may contribute to relapse prevention
in former smokers and smoking
cessation in current smokers.
ECs were used mainly for smoking
cessation; 74% of participants reported
not smoking for at least a few weeks
since using ECs, and 70% reported a
reduced urge to smoke.
Own-brand cigarette significantly
increased plasma nicotine and carbon
monoxide concentration, as well as
heart rate, within the first 5 minutes of
administration, whereas ECs and a sham
unlit cigarette did not; own-brand and
EC brands significantly decreased
tobacco abstinence symptom ratings.
ECs, with and without nicotine, resulted
in smoking cessation rates comparable
to nicotine patches with no significant
difference in adverse events.
The use of ECs, with and without nicotine,
in smokers not intending to quit resulted
in a decrease in cigarette consumption
without significant adverse events.
(continued)

Born et al

Table 1. (continued)
Type of Study/
Publication

Year

First Author

Funding Source

2011

Siegel29

Internet survey
(n = 300)

2011

Polosa30

2013
2014

Hajek31
Dutra32

Prospective clinical
proof-of-concept
study (n = 40)
Comment
Nationally
representative
cross-sectional
study (n =
39,882)

National Cancer Institute

2013

Kim35

Laboratory analysis

Ministry Health and Welfare

2013

Williams36

Laboratory analysis

Tobacco-Related Disease Research

Program, Cornelius Hopper Award,
National Institutes of Health fellowship,
and a TRDRP Postdoctoral Fellowship

2014

Kosmider37

Laboratory analysis

Institute of Occupational Medicine and

Environmental Health, Poland and
Medical University of Silesia, Poland

2012

Vardavas39

Laboratory-based
interventional
study (n = 30)

2013

Flouris40

2014

Kandel48

Nonrandomized
repeatedmeasures
controlled study
(n = 30)
Laboratory analysis

Summary of Findings
The 6-month point prevalence of smoking
abstinence among EC users was 31%;
66.8% reported reduced number of
cigarettes smoked.
ECs may substantially decrease cigarette
consumption in smokers not intending
to quit.

Howard Hughes Medical Institute,

National Institute of Health, and the
National Institute on Drug Abuse

EC use was associated with higher odds

of ever or current smoking, higher odds
of established smoking, higher odds of
planning to quit smoking among current
smokers, and, among experimenters,
lower odds of abstinence from
conventional cigarettes.
The maximum concentrations of total
tobacco-specific nitrosamines in
replacement liquids of ECs were .10
times more than those published by
Ruyan E-cigarette Company.
The presence of metal and silicate
particles in EC aerosol was higher than
or equal to the corresponding
concentrations in conventional cigarette
smoke.
Vapors from ECs contain toxic and
carcinogenic carbonyl compounds; both
solvent and battery output voltage
significantly affect levels of carbonyl
compounds in EC vapor.
EC use had immediate adverse physiologic
effects after short-term use, similar to
some of the effects seen with tobacco
smoking.
Short-term use of ECs generated smaller
changes in lung function but a similar
nicotinergic impact to tobacco
cigarettes.
Although ECs eliminated some of the
morbidity associated with tobacco, they
were pure nicotine-delivery devices,
which have the same effects on the
brain as the authors reported for
nicotine and pose the same risk of
addiction to other drugs and
experiences.

Abbreviations: CI, confidence interval; EC, electronic cigarette; FDA, Food and Drug Administration; OR, odds ratio; TRDRP, Tobacco Related Disease
Research Program.

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Figure 1. A PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flow diagram demonstrating how we conducted our literature review.

Figure 2. Examples of currently available electronic cigarettes (ECs), including a disposable EC that resembles a conventional cigarette (A)
and a rechargeable EC with a refillable liquid tank (B). Rechargeable ECs typically have several components, as shown in C.

conventional cigarettes compared with those who use ECs

alone.20 Many adults reported EC use as a substitute for
tobacco, although this use was not always associated with
an intention to quit.21 Of note, adolescent use correlated less
with efforts to cease tobacco use. Compared with nonsmokers, EC users tend to be younger, better educated, and of
higher income class.20
One important point for clinicians is that they must ask
about ECs specifically, especially in younger patients, who

are less likely to also be conventional cigarette users. These

patients may not report EC use when asked about smoking
history. One term commonly used by EC users is vaping
rather than smoking. In addition, nonverbal indicators of
nicotine use such as odor or skin and teeth discoloration are
not present in EC users.
Patterns of EC use vary; users report many reasons for
EC use, including the desire to quit or decrease smoking,
the belief of increased safety, minimal disturbance to others,

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Born et al

and/or the ability to use ECs indoors where conventional

smoking is not permitted.22,23 A recent European study
found that 76% of EC users were daily users. The average
time that respondents reported using ECs was 3 months,
with 150 puffs/d at an average nicotine concentration of 16
mg/mL. Those respondents who used daily were still using
daily at 1 month (98%), and most were still using at 1 year
(89%). Of those respondents who were concurrently smoking and vaping, 22% had quit smoking at 1 month and 46%
at 1 year. For those who continued smoking as well as
vaping, cigarette consumption decreased in the short term
but remained unchanged in the long term.24 Another recent
study suggested that only 1% reported using nonnicotine
liquid, and most were using a reusable tank system.25 This
study also found that 74% of respondents reported not
smoking for at least a few weeks since using ECs, and 70%
reported a decreased urge to smoke and a decreased interval
between vaping compared with the time between smoking.
It would seem that these and other studies suggest that ECs
are an effective tool for decreasing or ceasing conventional
tobacco use.

ECs for Smoking Cessation

Although commonly discussed as a tool for smoking cessation, not all EC users are current smokers trying to quit or
looking to reduce their tobacco consumption. In addition,
few studies have rigorously examined the utility of ECs as a
tool for smoking cessation; most use outdated EC technology that may deliver less nicotine and a less satisfying EC
experience. Supporters of ECs in smoking cessation cite the
importance of the behavioral motions of smoking/vaping as
a reason why ECs may be more effective than other cessation aides.20,26 Most existing literature focuses on decreasing cravings as reported by survey participants. Moreover,
studies that investigate the decrease or cessation of cigarette
usage are limited. The most widely discussed study, by
Bullen et al,27 is a randomized control trial comparing ECs
to nicotine patches, a mainstay of smoking cessation. This
study included 657 adult patients randomized into 3
groups: ECs (n = 289, mean age = 43.6 years), nicotine
patches (n = 295, mean age = 40.4 years), and placebo ecigarettes (n = 73, mean age = 43.2 years). ECs, with or
without nicotine, were modestly effective as cessation aids.
Smoking cessation at 6 months, although higher in nicotinecontaining ECs (7.3%), was not significantly different compared with nicotine patches (5.8%). The authors suggested
that this finding may be related to limited sample size. This
finding was recently corroborated by a randomized trial that
failed to find a significant difference in cessation rates
between ECs, patches, or nicotine-free ECs.14 Sample size
and outdated technology were, again, reported as limitations
of that study. Another randomized study comparing EC use
in smokers not interested in quitting investigated varying concentrations of nicotine liquid with nonnicotine cartridges in
an older, admittedly underperforming, EC model.28 Modest
benefit of ECs, with or without nicotine, in smoking cessation
was reported; 27% of those still using ECs at 1 year had

either reduced their conventional cigarette use or ceased altogether. No significant differences between groups were
noted, suggesting a limited role of nicotine content in smoking addiction in this cohort or, alternatively, reflecting the
inefficiency of the device used in the study. In addition to
these randomized controlled trials, few studies found
decreased usage of conventional cigarettes and increased cessation rates in smokers who use ECs.23,25,29 In fact, 1 study
investigated the effect of ECs on smoking reduction and cessation in smokers previously unwilling to quit (n = 40, mean
age 42.9 years) who had smoked at least 15 cigarettes for the
past 10 years. At 6 months, 32.5% of patients (13/40)
reduced their cigarette consumption by 50% from a median
of 25 cigarettes per day to 6 cigarettes per day (P \ .001). In
addition, 22.5% (9/40) quit smoking completely.
Cumulatively, 55% of participants either stopped smoking
completely or reduced cigarette consumption by approximately 50% at 6 months.30
As an alternative, a recent study suggested that ECs
should be considered not only for smokers hoping to quit
but as a safer alternative for those who wish to continue
smoking.31 The previously mentioned randomized trial
examined user health characteristics and found reduced
exhaled carbon monoxide, cough, xerostomia, dyspnea,
throat irritation, and headache with ECs. Withdrawal symptoms such as hunger, insomnia, irritability, anxiety, and
depression, normally examined during cessation studies,
were only infrequently reported among EC users.28 Smokers
tended to find EC use satisfying and reported fewer cravings
for conventional cigarettes.23,25 Assuming the vapor is
indeed safe, if current smokers were to replace conventional
cigarettes with ECs, safety for the users as well as those
around them would improve.
Alternatively, some worry that increased prominence of
vaping will draw more people into nicotine use. One study
of adolescents suggested that EC use may correlate with
increased likelihood of initiating conventional cigarette
use.32 This debate is playing out not only in the literature
but also in the national media.33,34

Safety of ECs
It is critical for clinicians to understand what is known
regarding the safety of ECs. The safety of these devices is
typically studied in 3 ways: (1) laboratory studies on the
content of liquid and vapors, (2) short-term effects of EC
use, and (3) long-term effects of EC use.26 Electronic cigarettes have not been around long enough or achieved widespread use adequate to evaluate the long-term effects.
However, much can be gained from laboratory studies, the
evolving literature on the short-term effects, and studies on
smoking reduction and cessation. As discussed previously,
the known content of the liquid used in ECs has been
shown to be relatively benign. However, studies tend to be
poorly designed and do not mimic exposure that would
occur from actual EC use but rather test the liquid directly
(rather than vapor) or vapor at much higher volume than
inhaled during EC use. In that regard, several studies

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identified toxins in EC vapor, including the aforementioned

study, suggesting the levels of 6 potentially toxic compounds to be 9- to 450-fold lower in the vapor of ECs than
in the smoke from conventional cigarettes.12 Tobaccospecific nitrosamine, a known carcinogen, in the liquid was
observed to be nearly identical to that of other nicotine
replacement therapies such as gum and patches.33 The
amounts of nitrosamines are reported to be 70 to 140 times
less than 1 cigarette.35
Although the flavorings used in ECs are generally considered safe for consumption, the effects of inhaling these substances remain unknown. In addition, because these liquids
are unregulated, the potential for contamination is unknown
and warrants further study. The actual device may contribute
to toxicity as well. A recent study found levels of silicate and
heavy metals to be increased in EC fluid and vapor compared
with cigarettes.36 Again, these substances were present in
very small concentrations but are known causes of respiratory
disease and cannot be ignored. The level of voltage used may
also contribute to EC toxicity. Increased voltages increased
toxin levels, including carcinogenic carbonyl compounds
such as formaldehyde and acetaldehyde.37 A popular new
method of EC use, known as dripping (eg, EC liquid is
dripped directly onto the device-heating element), creates
combustion reactions enough to produce these toxins.38
The negative short-term effects of using ECs revolve primarily around respiratory effects. A recent study found
levels of nitrous oxide in the blood and overall increased
respiratory resistance in EC users.39 Another study compared the effects of active and passive (ie, secondhand)
EC use with active and passive cigarette use and found the
respiratory effects were far smaller than those seen in cigarettes, but still present.40 It should be noted that respiratory
resistance seen in these studies can be attributed to mechanical irritation (similar to cold air) and may not represent a
physiologic change. Outside the respiratory system, ECs
have also been studied in relation to cardiac function.
Farsalinos et al41 examined the cardiac effects of EC use
and found that, contrary to cigarettes, systolic function, peripheral resistance, and blood carbon monoxide levels were
not affected by EC use.
As a final note, a recent article in the New York Times
discussed the dangers of accidental exposure to the liquid
used in ECs.42 Richtel42 pointed out that children may be
drawn to the liquid due to the often sweet-flavored and
brightly colored liquids. Signs of nicotine overdose include
seizures and vomiting and rarely can be fatal. Clinicians
should remind users to keep the liquid out of reach of children and to handle it with care when replacing liquid.
Although potentially dangerous, it should be noted that
lethal levels of nicotine are much higher than previously
thought, and it would be all but impossible to overdose on
nicotine through the use of ECs.15,43

Regulation of ECs
The rapid development of EC products has resulted in large
numbers of users of a largely unregulated product. Liquids

and devices are not held to standards similar to other smoking cessation and nicotine delivery products. New proposed
changes seek to classify ECs as tobacco products. The
FDAs Tobacco Control Act regulates other tobacco products such as cigarettes, roll-your-own tobacco, and smokeless tobacco. Interestingly, these products only may be
considered by health insurance plans on the individual
market when determining premiums.44 Customers who have
used any tobacco product an average of 4 or more times a
week in the past 6 months could be subject to an increased
premium by up to 50%.45
The proposed changes, covering ECs as well as pipe
tobacco and cigars, could not only affect the cost of health
care but also extend regulations such as banning the sale of
ECs to anyone younger than 18 years and requiring photo
ID for purchase.46 It would also regulate the quality and
content of EC liquids, requiring producers of these products
to report manufacturing processes and data regarding their
products and to have all new products approved by the
FDA.47 Notably, the regulations do not ban child-friendly
flavors or television marketing of ECs, as has been implemented for conventional cigarettes. If passed, these regulations are expected to be challenged by EC manufacturers
and are unlikely to take effect in the short term.

Implications for Practice

With the rapidly increasing use of ECs in people of all ages
throughout the United States, sales of electronic cigarettes
last year doubled to over $1.7 billion, while sales of conventional cigarettes decreased.24,34 The growing use among
adolescents and young adults is of particular concern.
Electronic cigarettes may correlate with an increased likelihood of initiating conventional cigarette use. Moreover, a
recent study reported that nicotine acts as a gateway drug
with neurological implications, and this effect is likely to
occur whether the exposure is from smoking tobacco, secondhand smoke exposure, or ECs.48 It is, therefore, essential
that physicians be up to date with the current recommendations and research involving the safety and risks of using
ECs, in addition to the benefits of ECs as smoking cessation
tools. Safety data indicate that ECs contain detectable levels
of toxins and suspected toxins in the EC liquid and produced vapor. These toxins, however, were generally found
at levels much lower than that of conventional cigarettes
and likely pose little risk as a result. With regard to the flavorings used in ECs, although generally considered safe for
consumption, the effects of inhaling these substances remain
unknown. As these liquids are unregulated, the potential for
contamination is uncertain, and product consistency, including that of nicotine, is of significant concern.
The current literature does not support the use of ECs as
a smoking cessation tool. Several trials suggest that ECs
may be beneficial to some smokers who are looking to quit
or reduce smoking. However, ECs have not been around
long enough or adequately used to evaluate their long-term
effects. Furthermore, most current studies are limited in
sample size and do not demonstrate significant rates of

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Born et al

smoking reduction and cessation comparable to that of

already approved FDA-approved nicotine replacement
therapies.
In summary, with the ever-growing awareness and use of
ECs, it is necessary for physicians to counsel their patients
on the safety of these devices. Clinicians must ask about EC
use specifically as it may be not reported when patients are
asked about smoking history. Undoubtedly, this immense
increase in popularity will result in more patient inquiries
regarding these devices. Patients with a variety of otolaryngologic conditions, including cancer, may benefit from a direct
discussion regarding ECs. The authors believe that FDAapproved treatments for smoking cessation, which are proven
safe and effective, should still be recommended. Studies
investigating the safety and efficacy of ECs are absolutely
critical, in addition to investigation regarding addiction potential, cancer risk, and effect of secondhand exposure, as well
as short-term and long-term health issues of EC use.
Author Contributions
Hayley Born, acquisition, analysis, and interpretation of data for
the work, drafting and revising the work, final approval of the version to be published, agreement to be accountable for all aspects of
the work; Michael Persky, acquisition, analysis, and interpretation
of data for the work, drafting and revising the work, final approval
of the version to be published, agreement to be accountable for all
aspects of the work; Dennis H. Kraus, acquisition, analysis, and
interpretation of data for the work, drafting and revising the work,
final approval of the version to be published, agreement to be
accountable for all aspects of the work; Robert Peng, acquisition,
analysis, and interpretation of data for the work, drafting and revising the work, final approval of the version to be published, agreement to be accountable for all aspects of the work; Milan R.
Amin, acquisition, analysis, and interpretation of data for the
work, drafting and revising the work, final approval of the version
to be published, agreement to be accountable for all aspects of the
work; Ryan C. Branski, conception/design, interpretation of data
for the work, revising work critically for important intellectual
content, final approval of the version to be published, agreement to
be accountable for all aspects of the work.

Disclosures
Competing interests: None.
Sponsorships: None.
Funding source: None.

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