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Vaping Nicotine Is Far Less Harmful Than Smoking Tobacco

whether cognitive impairment was reversed. The
advantage of both these approaches would be to
minimize reverse causality and known and unknown
confounding. In our opinion, this is the best way to
clarify the causal nature of the association between
impaired lung function and dementia and, if this is the
case, potentially shed light on the underlying mechanism.
Tom C. Russ, PhD, MRCPsych
Edinburgh, United Kingdom
Mika Kivimäki, FMedSci
G. David Batty, PhD, DSc
London, United Kingdom
AFFILIATIONS: Alzheimer Scotland Dementia Research Centre (Drs
Russ and Batty); Edinburgh Dementia Prevention and the Division of
Psychiatry, Centre for Clinical Brain Sciences (Dr Russ), University
of Edinburgh; and the Department of Epidemiology and Public
Health (Drs Kivimäki and Batty), University College.
for author conicts of interest.
Alzheimer Scotland Dementia Research Centre, University of
Edinburgh, 7 George Square, Edinburgh, EH8 9JZ, United
Kingdom; e-mail:
Copyright Ó2020 American College of Chest Physicians. Published
by Elsevier Inc. All rights reserved.
1. Russ TC, Kivimäki M, Batty GD. Respiratory disease and lower
pulmonary function as risk factors for dementia: a systematic review
with meta-analysis. Chest. 2020;157(6):1538-1558.
2. Munafo M, Davey-Smith G. Repeating experiments is not enough.
Nature. 2018;553:399-400.
3. Shrine N, Guyatt AL, Erzurumluoglu AM, et al. New genetic signals
for lung function highlight pathways and chronic obstructive
pulmonary disease associations across multiple ancestries. Nat Genet.
Vaping Nicotine Is Far Less
Harmful Than Smoking
To the Editor:
In a previous issue of CHEST (May 2020), Bozier et al
reviewed the recent research on the potential health
effects of e-cigarettes. We would like to comment on
several of the claims made in the article.
The most relevant question for smokers is whether vaping
nicotine is less harmful than smoking the cigarettes it is
designed to replace. The evidence suggests it is far less
harmful. The National Academies of Sciences,
Engineering, and Medicine report
found substantial
evidence that exposure to potentially toxic substances
from e-cigarettes is signicantly lower compared with
combustible tobacco cigarettesand reduced short-term
adverse health outcomes in several organ systems.
The authors quite rightly conclude that e-cigarette use
is not risk-free for non-smokers.However,
international studies of adults and youth show that
current use of e-cigarettes by never smokers is rare, and
regular use is very rare, usually <0.5%.
Most of the research on the harms of e-cigarettes is from
in vitro and animal studies. How these ndings translate
to health effects in humans is uncertain, when many
human studies show substantial health improvements in
smokers who switch to vaping.
The recent outbreak of lung injuries in the United States
electronic-cigarette, or vaping, product use-associated
lung injury (EVALI)
was not due to nicotine vaping.
Most, if not all, cases were the result of vaping black-
market tetrahydrocannabinol contaminated with
vitamin E acetate.
No cases have been associated with
commercial nicotine vaping.
The authors claim that we cannot exclude the possibility
that e-cigarettes pose a similar, lesser, or greater cancer
risk than cigarette smokingbecause of the presence of
carcinogens and potential adverse effects in two studies.
Given the greatly reduced number of carcinogens and
their lower concentration in e-cigarette vapor, it is very
likely that the cancer risk from vaping is only a tiny
fraction of the risk from smoking.
Finally, the authors appear to misunderstand the role of
tobacco harm reduction in questioning the value of
vaping as a quitting aid when many ex-smokers
continue to vape after quitting. Replacing a high-risk
behavior with a far less harmful one is a well-accepted
public health strategy, for example, methadone
maintenance for heroin addiction.
Evidence from randomized controlled trials, population
studies, and better-quality observational studies shows
that e-cigarettes are effective quitting aids.
The authors
are correct that short-term nicotine replacement therapy
is less harmful than vaping, but it is also far less effective
for quitting, and very few smokers use it.
Colin Paul Mendelsohn, MB BS (Hons)
Double Bay, NSW, Australia
Wayne Hall, PhD
Saint Lucia, QLD, Australia 835
AFFILIATIONS: From the University of New South Wales Ringgold
standard institution - School of Public Health and Community
Medicine (Dr Mendelsohn); and the University of Queensland (Dr
Hall), Saint Lucia Campus Ringgold standard institution, Centre for
Youth Substance Abuse Research.
reported to CHEST the following: C. P. M. has received funding from
Pzer Australia, Johnson & Johnson Pacic and Perrigo Australia for
teaching, consulting, and conference expenses. C. P. M. has never
received any funding or payments from e-cigarette or tobacco
companies; serves as a Board member of the Australian Tobacco
Harm Reduction Association (ATHRA), a health promotion charity.
ATHRA has received donations in the past from Australian vape
shops. This formally ceased in March 2019. None declared (M. H.).
CORRESPONDENCE TO: Colin Mendelsohn, MB BS (Hons),
University of New South Wales Ringgold standard institution, School
of Public Health and Community Medicine, 11 Carlotta Rd, Double
Bay, NSW, 2028, Australia; e-mail:
Copyright Ó2020 American College of Chest Physicians. Published
by Elsevier Inc. All rights reserved.
1. Bozier J, Chivers EK, Chapman DG, et al. The evolving landscape
of e-cigarettes: a systematic review of recent evidence. Chest.
2. National Academies of Sciences, Engineering and Medicine. Public
Health Consequences of e-Cigarettes. Washington, DC: The National
Academies Press; 2018.
3. Blount BC, Karwowski MP, Shields PG, et al. Vitamin E acetate in
bronchoalveolar-lavage uid associated with EVALI. N Engl J Med.
4. Stephens WE. Comparing the cancer potencies of emissions from
vapourised nicotine products including e-cigarettes with those of
tobacco smoke [published online ahead of print August 4, 2017]. Tob
Control. http://doi.10.1136/tobaccocontrol-2017-053808.
5. Mendelsohn C, Hall W, Borland R. Could vaping help lower smoking
rates in Australia? Drug Alcohol Rev. 2020;39(4):415-418.
To the Editor:
We thank Drs Mendelsohn and Hall for their response
to our systematic review of current literature
surrounding the (potential) health effects of
We acknowledge their commitment to
improving health outcomes for tobacco cigarette
smokers and welcome their opinion in the current
debate. While supporting our conclusion that smokers
who switch to e-cigarettes may experience harm
reduction,they disagree with our cautious approach by
not endorsing e-cigarettes as a harm reduction strategy.
Harm reduction is founded on the understanding that
complete abstinence is an unrealistic goal. This is likely
untrue for most smokers, with recent data from the
National Health Interview Survey and Cancer Control
Supplement reporting that 80% of older adults who had
ever smoked had successfully quit.
Nonetheless, if we
consider those tobacco smokers who are unable to
successfully quit despite the use of tobacco cessation
counseling and pharmacotherapy, one must assess the
harm reduction efcacy of e-cigarettes. In arguing that
e-cigarettes are effective quitting aids,Drs Mendelsohn
and Hall draw on two randomized controlled trials of
e-cigarettes as a smoking cessation tool. Hajek et al
reported one-year smoking abstinence rates of 18% in
those using e-cigarettes vs 9.9% in the nicotine
replacement therapy (NRT) group. Recently, Walker
et al
reported 6-month smoking abstinence rates of
7% with e-cigarettes plus nicotine patches vs 2% with
nicotine patches alone. Thus, e-cigarettes may be more
effective at promoting smoking abstinence than NRT,
but the effect is rather modest. When also considering
that e-cigarette use may increase the risk of smoking
and promote smoking initiation,
we are left
questioning the public health benet of e-cigarettes. We
acknowledge that from an individual perspective,
e-cigarettes may be an appropriate harm reduction
strategy. However, this would require identication of
the subset of smokers in whom e-cigarettes are
efcacious for smoking cessation. At present, such a
phenotype is unknown.
Drs Mendelsohn and Hall acknowledge that e-cigarettes
are not without risk. It is therefore important to ask
whether long-term e-cigarette use sufciently lowers risk
to translate to improvements in long-term health
outcomes. The evidence of little harm reduction after
reduction of tobacco smoking without complete
makes this question particularly pertinent.
The limited evidence in humans reveals short-term
improvements in respiratory health for tobacco smokers
who transition to e-cigarettes.
However, emerging
preclinical evidence suggests that long-term use may
increase the risk for lung cancer and pre-cancerous
bladder lesions.
However, whether the toxicant burden
associated with lifetime e-cigarette use, on top of previous
tobacco smoking history, does or does not contribute to
life-time risk of respiratory disease, cardiovascular
disease, cancer, and mortality is unknown.
The goal of our review was to systematically summarize
the recent literature, regardless of the ndings, on the
possible health effects of e-cigarette use. We hope that in
doing so it has provided much-needed clarity as to the
current evidence and will be an impetus for future
research and regulation.
David G. Chapman, PhD
Sydney, NSW, Australia
Alexander N. Larcombe, PhD
Perth, WA, Australia
836 Correspondence [158#2 CHEST AUGUST 2020 ]
... The hidden and unaddressed risks of litigation could also be a significant reason behind tepid professional support for e-cigarettes, which are likely to be less harmful than tobacco cigarettes. [86][87][88][89][90] Large, well conducted and funded clinical trials are needed to provide long-term safety and efficacy data along with a fully characterized adverse-effect profile in naturalistic real-world settings. Primary care practitioners and students' need to be supported by the evidence to inform their practice. ...
Full-text available
Introduction Pharmacy staff are a trusted source of advice on the safe and appropriate use of medicines and devices. Retail pharmacies deliver smoking cessation services and sell e-cigarettes in the UK. This review asks ‘what knowledge, experience and ability do staff have to support e-cigarette users to quit smoking’. Methods A systematic literature search was undertaken drawn on predefined eligibility criteria and a comprehensive search strategy following the PRISMA guideline. Eligible papers reported survey-research published in English from 2015 to 2020. PubMed, Google Scholar, OVID, EMBASE and MEDLINE Databases were searched. No restrictions on study design or language were applied. Two reviewers independently screened for inclusion/exclusion and then extracted the relevant information from the articles for synthesis. Results Of 12 potentially eligible full-text studies, 1 was a duplicate, 7 were excluded as per eligibility criteria. Four papers were finally included in this literature review. Two studies indicated that pharmacy staff are less confident in giving advice on e-cigarette use. Knowledge on the adverse effects of e-cigarettes compared to traditional smoking cessation aids remain unclear. In one study, 42% of community pharmacists did not believe that e-cigarettes could be used for smoking cessation. Three studies identified need for specific regulations and professional support. The overall certainty of the evidence is ‘low’ or ‘very low’, with moderate levels of bias. Conclusion Pharmacists may be well placed to implement e-cigarette smoking cessation interventions, but most practitioners lacked knowledge and ability to support these customers citing unclear risk of harm. Pharmacists felt secure in recommending traditional cessation tools. Further regulation, guidelines and training is needed. Findings may be less generalizable in countries where e-cigarettes are banned. Their extent of knowledge, experience and ability to support users of e-cigarettes within their community to quit smoking is lacking.
Introduction: To understand the impact of e-cigarette devices, flavours, nicotine levels and prices on adult e-cigarette users' choices among closed-system and open-system e-cigarettes, cigarettes and heated tobacco products (HTPs). Methods: Online discrete choice experiments were conducted among adult (≥18 years) e-cigarette users (n=2642) in August 2020. Conditional logit regressions were used to assess the relative impact of product attributes and the interactions between product attributes and user characteristics, with stratified analyses to examine differences by smoking status and primarily used e-cigarette device and flavour. Results: On average, participants preferred non-tobacco and non-menthol flavours most, preferred open-system over closed-system e-cigarettes and preferred regular nicotine level over low nicotine level. However, the preference varied by demographics, smoking status and the primarily used e-cigarette device and flavour. The differences in preference among products/devices were larger than the difference among flavours or nicotine levels. Participants who primarily used closed-system e-cigarettes exhibited similar preferences for closed-system and open-system e-cigarettes, but those who primarily used open-system e-cigarettes preferred much more open-system over closed-system e-cigarettes. HTP was the least preferred product, much lower than cigarettes in general, but participants living in states where IQOS is being sold had similar preferences to cigarettes and HTPs. Conclusions: People are unlikely to switch to another product/device because of the restriction of flavour or nicotine level. If non-tobacco and non-menthol flavours were banned from open-system e-cigarettes, users may switch to menthol flavour e-cigarettes. Intervention strategies should be tailored to specific groups.
Full-text available
Smoking continues to be a burden to economies and healthcare systems across the world. One proposed solution to the problem has been e-cigarettes; however, as a relatively new product in the market, little is known about their potential health impacts. Furthermore, e-cigarettes continue to evolve at a rapid rate, making it necessary to regularly review and synthesize available studies. Whilst e-cigarettes are marketed as a smoking cessation tool by some manufacturers, the reality is that many non-smokers, including youth, are using them. In this review we focus on two major demographics - smokers and non-smokers, and evaluate the most recent data (2018-2019) regarding the potential health effects of e-cigarettes. We assessed peer-reviewed studies on health impacts of e-cigarettes with particular focus on common questions asked by policy makers, clinicians, and scientists: 1. What are the effects of e-cigarettes compared with air/not-smoking?; 2. Is there any direct evidence of harm or benefit to humans?; 3. Is there a risk from second-hand exposure?; 4. What are the risks and/or benefits of e-cigarettes compared with tobacco cigarette use?; 5. Are there risks or benefits to specific populations - people with COPD or asthma, and pregnant women (and their offspring)?; 6. What are the effects of flavoring chemicals?; 7. What are the effects of including nicotine in e-liquids?; 8. How often is nicotine-level labelling incorrect? and 9. What are the risks when e-cigarettes explode?
Full-text available
In this brief article, we review the evidence on whether easier access to vaping could help lower smoking rates in Australia. To make a convincing case for vaping the following conditions need to be met: that vaping assists in smoking cessation; that the prevalence of vaping is high enough to produce measurable effects at a population level; and that the decline in smoking prevalence is slower in countries where vaping is less common. The evidence suggests that these criteria are satisfied. © 2020 Australasian Professional Society on Alcohol and other Drugs
Full-text available
Background: The causative agents for the current national outbreak of electronic-cigarette, or vaping, product use-associated lung injury (EVALI) have not been established. Detection of toxicants in bronchoalveolar-lavage (BAL) fluid from patients with EVALI can provide direct information on exposure within the lung. Methods: BAL fluids were collected from 51 patients with EVALI in 16 states and from 99 healthy participants who were part of an ongoing study of smoking involving nonsmokers, exclusive users of e-cigarettes or vaping products, and exclusive cigarette smokers that was initiated in 2015. Using the BAL fluid, we performed isotope dilution mass spectrometry to measure several priority toxicants: vitamin E acetate, plant oils, medium-chain triglyceride oil, coconut oil, petroleum distillates, and diluent terpenes. Results: State and local health departments assigned EVALI case status as confirmed for 25 patients and as probable for 26 patients. Vitamin E acetate was identified in BAL fluid obtained from 48 of 51 case patients (94%) in 16 states but not in such fluid obtained from the healthy comparator group. No other priority toxicants were found in BAL fluid from the case patients or the comparator group, except for coconut oil and limonene, which were found in 1 patient each. Among the case patients for whom laboratory or epidemiologic data were available, 47 of 50 (94%) had detectable tetrahydrocannabinol (THC) or its metabolites in BAL fluid or had reported vaping THC products in the 90 days before the onset of illness. Nicotine or its metabolites were detected in 30 of 47 of the case patients (64%). Conclusions: Vitamin E acetate was associated with EVALI in a convenience sample of 51 patients in 16 states across the United States. (Funded by the National Cancer Institute and others.).
Background: In addition to affecting the oxygen supply to the brain, pulmonary function is a marker of multiple insults throughout life (including smoking, illness, and socioeconomic deprivation). In this meta-analysis of existing longitudinal studies, we tested the hypothesis that lower pulmonary function and respiratory illness are linked to an elevated risk of dementia. Method: We conducted a systematic review of longitudinal studies using PubMed until April 1st, 2019 and, where possible, pooled results in random-effects meta-analyses. Results: We identified eleven studies relating pulmonary function to later dementia risk, and eleven studies of respiratory illness and dementia (including one which assessed both). The lowest quartile of Forced Expiratory Volume in one second (FEV1) compared with the highest was associated with a 1.4-fold (1.46, 95%CI 0.77-2.75) increased dementia risk (Ntotal=62,209, two studies). An decrease of one standard deviation in FEV1 was associated with a 28% increase in dementia risk (1.28, 95%CI 1.03-1.60; Ntotal=67,505; six studies). Respiratory illness was also associated with increased dementia risk to a similar degree (1.54, 1.30-1.81, Ntotal=288,641, 11 studies). Conclusions: Individuals with poor pulmonary function experience increased risk of dementia. The extent to which the association between poor pulmonary function and dementia is causal remains unclear and requires examination.
Background Quantifying relative harm caused by inhaling the aerosol emissions of vapourised nicotine products compared with smoking combustible tobacco is an important issue for public health. Methods The cancer potencies of various nicotine-delivering aerosols are modelled using published chemical analyses of emissions and their associated inhalation unit risks. Potencies are compared using a conversion procedure for expressing smoke and e-cigarette vapours in common units. Lifetime cancer risks are calculated from potencies using daily consumption estimates. Results The aerosols form a spectrum of cancer potencies spanning five orders of magnitude from uncontaminated air to tobacco smoke. E-cigarette emissions span most of this range with the preponderance of products having potencies<1% of tobacco smoke and falling within two orders of magnitude of a medicinal nicotine inhaler; however, a small minority have much higher potencies. These high-risk results tend to be associated with high levels of carbonyls generated when excessive power is delivered to the atomiser coil. Samples of a prototype heat-not-burn device have lower cancer potencies than tobacco smoke by at least one order of magnitude, but higher potencies than most e-cigarettes. Mean lifetime risks decline in the sequence: combustible cigarettes >> heat-not-burn >> e-cigarettes (normal power)≥nicotine inhaler. Conclusions Optimal combinations of device settings, liquid formulation and vaping behaviour normally result in e-cigarette emissions with much less carcinogenic potency than tobacco smoke, notwithstanding there are circumstances in which the cancer risks of e-cigarette emissions can escalate, sometimes substantially. These circumstances are usually avoidable when the causes are known.
Repeating experiments is not enough
  • M Munafo
  • G Davey-Smith
Munafo M, Davey-Smith G. Repeating experiments is not enough. Nature. 2018;553:399-400.