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Changing Perceptions of Harm of E-Cigarettes Among U.S. Adults, 2012–2015

Open AccessPublished:October 26, 2016DOI:https://doi.org/10.1016/j.amepre.2016.08.039

      Introduction

      Although the impact of long-term use of electronic cigarettes (e-cigarettes) on health is still unknown, current scientific evidence indicates that e-cigarettes are less harmful than combustible cigarettes. The study examined whether perceived relative harm of e-cigarettes and perceived addictiveness have changed during 2012–2015 among U.S. adults.

      Methods

      Data were from Tobacco Products and Risk Perceptions surveys of probability samples representative of U.S. adults in 2012, 2014, and 2015. Changes over time in perceived harmfulness of e-cigarettes were examined using pairwise comparisons of proportions and multinomial logistic regression analysis. Analyses were conducted in January 2016.

      Results

      Whereas 11.5% and 1.3% of adults perceived e-cigarettes to have about the same level of harm and to be more harmful than cigarettes, respectively, in 2012, 35.7% and 4.1% did so in 2015. The proportion of adults who thought e-cigarettes were addictive more than doubled during 2012–2015 (32.0% in 2012 vs 67.6% in 2015). Compared with 2012, the odds of perceiving e-cigarettes to be equally or more harmful (than to be less harmful) doubled (95% CI=1.64, 2.41) in 2014, and tripled (95% CI=2.60, 3.81) in 2015.

      Conclusions

      There is an increase in the proportion of U.S. adults who misperceive the harm of e-cigarettes and consider them to be as harmful as combustible cigarettes. The study highlights the need to design public health messages that accurately interpret the scientific data on the potential harm of e-cigarettes and clearly differentiate the absolute from the relative harm of e-cigarettes.

      Introduction

      Breathing smoke from combustible cigarettes is a leading cause of preventable disease and death in the U.S., and causes the majority of tobacco-related death and disease.
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      and 4% had used them every day or some days.

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      Although the impact of long-term use of e-cigarettes on health is still unknown, the available scientific evidence indicates that e-cigarettes are less harmful than combustible cigarettes,
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      Previous studies have identified how consumers perceive e-cigarette harmfulness and addictiveness.
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      In this study, data were from three web-based surveys using probability samples representative of non-institutionalized U.S. adults conducted in 2012, 2014, and 2015. Using the same measures to define perceived harmfulness and perceived addictiveness of e-cigarettes in the three surveys allowed for comparisons over time. As the nature of the regulatory environment influences perceptions of e-cigarettes,

      Yong HH, Borland R, Balmford J, et al. Prevalence and correlates of the belief that electronic cigarettes are a lot less harmful than conventional cigarettes under the different regulatory environments of Australia and the United Kingdom. Nicotine Tob Res. In press. Online May 17, 2016. http://dx.doi.org/10.1093/ntr/ntw137.

      it was hypothesized that perceptions regarding e-cigarettes may have changed over the past 4 years in response to the changing regulatory environment.
      Deeming tobacco products to be subject to the Federal Food, Drug, and Cosmetic Act, as amended by the Family Smoking Prevention and Tobacco Control Act; restrictions on the sale and distribution of tobacco products and required warning statements for tobacco products. Final rule.
      The purposes of the current study were to determine whether the perceived harm of e-cigarettes relative to the harm of combustible cigarettes and perceived addictiveness have changed over a 4-year period (2012–2015) among U.S. adults and to examine factors associated with misperceiving e-cigarettes as equally or more harmful than combustible cigarettes.

      Methods

       Data Sample

      This study used data from the 2012 (August); 2014 (June–November); and 2015 (August–September) Tobacco Products and Risk Perceptions Surveys conducted by the Georgia State University School of Public Health. These surveys were national, cross-sectional surveys of a probability sample drawn from KnowledgePanel, a probability-based online research panel designed to be representative of non-institutionalized U.S. adults. More details on these surveys can be found in previous publications.
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      • Nguyen K.H.
      • Dube S.R.
      Trends in awareness and use of electronic cigarettes among U.S. adults, 2010-2013.
      • Weaver S.R.
      • Majeed B.A.
      • Pechacek T.F.
      • et al.
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      • Eriksen M.P.
      Opinions about electronic cigarette use in smoke-free areas among U.S. Adults, 2012.
      For each survey, a probability sample of U.S. adults from KnowledgePanel (including a representative oversample of cigarette smokers in 2014 and 2015) was selected. A total of 4,170, 5,717, and 6,051 respondents completed the 2012, 2014, and 2015 surveys, respectively, yielding final-stage completion rates of 65.1% in 2012, 74.4% in 2014, and 76.0% in 2015. A study-specific post-stratification weight was computed using an iterative proportional fitting procedure (raking) to adjust for survey non-response as well as for oversampling of smokers. Demographic and geographic distributions from the most recent Current Population Surveys for the respective survey years were employed as benchmarks for adjustment, and included gender, age, race/ethnicity, education, household income, Census region, metropolitan area, and Internet access. For the present study, the sample of interest consisted of 2,808, 5,234, and 5,389 participants in 2012, 2014, and 2015, respectively, who reported prior awareness of e-cigarettes. This study was approved by the IRB at Georgia State University. Key demographic characteristics of the samples are shown in Appendix Table 1 (available online).

       Measures

      Participants who indicated that they have heard about e-cigarettes were considered aware. Ever trying e-cigarettes was assessed by asking participants who had indicated prior awareness of e-cigarettes whether they have ever tried e-cigarettes/electronic vapor products, even just one time. Those who responded yes were defined as having ever tried e-cigarettes.
      Perceived harmfulness of e-cigarettes relative to combustible cigarettes was assessed using the question: Is using [e-cigarettes/electronic vapor products] less harmful, about the same level of harm, or more harmful than smoking regular cigarettes? Participants could also select I don’t know. Perceived addictiveness of e-cigarettes was measured with the question: Do you think people can become addicted to [e-cigarettes/electronic vapor products]? Responses included yes, no, and I don’t know.
      Sociodemographic characteristics included in this study were: sex, age, race/ethnicity, educational attainment, annual household income, and U.S. Census region. Current smokers were defined as adults who had smoked at least 100 cigarettes during their lifetime and reported currently smoking every day or some days. Former smokers were defined as adults who had smoked at least 100 cigarettes and responded not at all to the question about current smoking. Those who had not smoked at least 100 cigarettes in their lifetime were defined as never smokers.

       Statistical Analysis

      Analyses were conducted in January 2016 using Stata, version 13, to obtain design-based (weighted) point estimates and 95% CIs of the response category proportions for the perception items, overall and by smoking status. Pairwise comparisons of the proportions were conducted to test the difference between the proportions across surveys.
      The characteristics of participants who responded about the same and those who responded more harmful were examined and found to be similar. Given that only a small proportion of respondents reported more harmful and that they were not fundamentally different from adults who reported about the same, the two response categories were grouped into one category representing adults who perceived e-cigarettes as equally or more harmful than combustible cigarettes. Perceived harmfulness of e-cigarettes was analyzed using multinomial logistic regression. To identify characteristics of adults who were misinformed about the relative harm of e-cigarettes, for this analysis, the response category “less harmful” was used as the ref group of the dependent variable, in alignment with the scientific evidence.
      • Hecht S.S.
      • Carmella S.G.
      • Kotandeniya D.
      • et al.
      Evaluation of toxicant and carcinogen metabolites in the urine of e-cigarette users versus cigarette smokers.
      The survey year and perceived addictiveness were the independent variables, and ever trying e-cigarettes and demographic characteristics were covariates.
      Using the most recent survey data, bivariate tests of associations (chi-square) were conducted to examine differences in the perceived harmfulness of e-cigarettes relative to combustible cigarettes and the perceived addictiveness of e-cigarettes across participant characteristics. For all analyses, p-values <0.05 were considered statistically significant.

      Results

      Table 1 depicts the perceived harmfulness of e-cigarettes relative to cigarettes and the perceived addictiveness among all participants, current smokers, and former smokers. There was an increase in the proportions of adults who perceived e-cigarettes to have “about the same level of harm” as or to be “more harmful” than cigarettes (Appendix Figure 1, available online). Whereas about 12.9% of adults thought e-cigarettes were “equally or more harmful than cigarettes” in 2012, nearly four in ten adults (39.8%) held this perception in 2015 (p<0.001). This increase in the perceived relative harm occurred in tandem with a decline in the proportions of adults who were uncertain (I don’t know) or perceived e-cigarettes as less harmful than cigarettes. The proportion of adults who were uncertain about the relative harm of e-cigarettes decreased from nearly half (47.8%) in 2012 to 29.5% in 2015. A similar, though less pronounced, decrease was observed in the proportions of adults who perceived e-cigarettes as less harmful than cigarettes (39.4% in 2012 vs 30.7% in 2015). The proportion of adults who perceived e-cigarettes to be addictive more than doubled from 32.0% in 2012 to 67.6% in 2015 (p<0.001).
      Table 1Perceived Harmfulness and Perceived Addictiveness of E-cigarettes Among U.S. Adults, Overall and by Smoking Status: 2012–2015
      PerceptionsOverall, % (95% CI)Current smokers, % (95% CI)Former smokers, % (95% CI)
      2012 (n=2,808)2014 (n=5,234)2015 (n=5,389)201220142015201220142015
      Perceived harmfulness
      Perceived harmfulness was measured using this question: Is using e-cigarettes less harmful, about the same level of harm, or more harmful than smoking regular cigarettes?
       Less harmful39.4 (36.9, 41.9)35.2 (33.8, 36.7)30.7 (29.1, 32.3)44.7 (39.1, 50.5)39.8 (36.6, 43.0)36.0 (32.2, 40.0)35.0 (30.7, 39.5)33.2 (30.6, 35.9)28.3 (25.6, 31.2)
       About the same11.5 (10.0, 13.2)28.4 (27.0, 29.8)35.7 (34.1, 37.3)11.0 (8.0, 15.0)24.1 (21.4, 27.1)30.8 (27.0, 34.8)10.8 (8.0, 14.3)24.7 (22.4, 27.2)34.1 (31.2, 37.2)
       More harmful1.3 (0.8, 2.2)2.5 (2.0, 3.0)4.1 (3.4, 5.0)0.7 (0.1, 3.7)2.5 (1.6, 4.0)4.3 (2.6, 6.9)1.1 (0.5, 2.3)2.5 (1.7, 3.6)4.0 (2.7, 6.0)
       I don’t know47.8 (45.3, 50.3)33.9 (32.5, 35.4)29.5 (28.0, 31.1)43.6 (37.9, 49.3)33.6 (30.5, 36.9)28.9 (25.3, 32.7)53.2 (48.6, 57.8)39.7 (37.0, 42.4)33.5 (30.7, 36.5)
      Perceived addictiveness
      Perceived addictiveness was measured using this question: Can people become addicted to e-cigarettes?
       Yes32.0 (29.7, 34.4)63.2 (61.8, 64.7)67.6 (66.0, 69.2)25.3 (20.7, 30.6)48.0 (44.7, 51.3)56.7 (52.6, 60.8)28.1 (24.2, 32.4)63.0 (60.2, 65.7)67.9 (65.0, 70.7)
       No11.3 (9.7, 13.1)4.6 (3.9, 5.3)3.8 (3.1, 4.5)16.0 (12.0, 20.9)9.5 (7.7, 11.8)8.8 (6.7, 11.5)9.6 (7.2, 12.7)3.6 (2.6, 5.1)2.7 (1.8, 4.0)
       I don’t know56.8 (54.3, 59.3)32.2 (30.8, 33.6)28.6 (27.1, 30.2)58.7 (52.9, 64.3)42.5 (39.2, 45.8)34.5 (30.6, 38.5)62.3 (57.8, 66.6)33.5 (30.8, 36.2)29.4 (26.7, 32.3)
      Note: All % are weighted column %.
      a Perceived harmfulness was measured using this question: Is using e-cigarettes less harmful, about the same level of harm, or more harmful than smoking regular cigarettes?
      b Perceived addictiveness was measured using this question: Can people become addicted to e-cigarettes?
      Regardless of smoking status, the perceptions that e-cigarettes were equally or more harmful and that they were addictive increased during 2012–2015. There was an increase in the proportion of current smokers who perceived e-cigarettes to be equally or more harmful than cigarettes (11.7% in 2012 vs 35.1% in 2015, p<0.001). The proportion of current smokers who believed e-cigarettes to be addictive more than doubled (25.3% in 2012 vs 56.7% in 2015, p<0.001).
      Bivariate tests revealed that perceived harmfulness of e-cigarettes was associated with demographic characteristics and ever trying e-cigarettes, in 2015 (Table 2). Compared with never users of e-cigarettes, those who ever tried were more likely to perceive e-cigarettes to be less harmful than cigarettes (25.7%, 95% CI=24.1, 27.4 vs 51.2%, 95% CI=47.3, 55.1; p<0.001).
      Table 2Perceived Harm of E-cigarettes Relative to Cigarettes by Participant Characteristics Among U.S. Adults: 2015
      CharacteristicsCompared to cigarettes, smoking e-cigarettes is:
      Less harmful, % (95% CI)About the same level of harm, % (95% CI)More harmful, % (95% CI)I don’t know, % (95% CI)
      Sex***
       Male34.6 (32.4, 36.9)33.5 (31.3, 35.8)3.6 (2.7, 4.7)28.3 (26.2, 30.5)
       Female26.9 (24.8, 29.1)37.8 (35.4, 40.1)4.6 (3.5, 6.1)30.7 (28.5, 33.1)
      Age (years)***
       18–2445.5 (38.9, 52.3)31.3 (25.3, 38.0)3.6 (1.6, 7.8)19.6 (14.9, 25.4)
       25–3436.8 (33.2, 40.5)38.1 (34.5, 41.8)4.5 (3.0, 6.8)20.7 (17.5, 24.3)
       35–4430.7 (26.9, 34.6)38.0 (34.1, 42.1)6.4 (4.1, 9.9)25.0 (21.7, 28.6)
       45–5426.9 (23.5, 30.5)37.6 (33.5, 41.9)5.5 (3.7, 7.9)30.0 (26.3, 34.0)
       55–6427.4 (24.2, 30.9)34.2 (30.7, 37.9)2.5 (1.4, 4.3)35.9 (32.3, 39.6)
       ≥6522.9 (20.2, 25.8)32.9 (29.7, 36.2)2.4 (1.7, 3.5)41.9 (38.3, 45.5)
      Race/ethnicity**
       White, NH32.7 (30.9, 34.5)34.6 (32.7, 36.5)3.3 (2.6, 4.1)29.5 (27.8, 31.3)
       Black, NH22.3 (18.0, 27.2)35.7 (30.3, 41.5)6.7 (4.1, 10.6)35.4 (29.9, 41.2)
       Other, NH31.1 (24.5, 38.5)40.7 (33.3, 48.5)6.4 (2.9, 13.3)21.9 (16.3, 28.8)
       Hispanic27.3 (23.2, 31.9)38.4 (33.9, 43.1)5.3 (3.2, 8.4)29.0 (24.8, 33.7)
      Education***
       <High school29.9 (23.9, 36.6)34.5 (28.3, 41.3)6.7 (3.9, 11.4)28.9 (23.3, 35.3)
       High school27.2 (24.6, 29.8)34.0 (31.3, 36.8)3.9 (2.7, 5.6)35.0 (32.2, 37.8)
       Some college31.4 (28.5, 34.5)35.1 (32.0, 38.4)5.0 (3.6, 7.0)28.4 (25.5, 31.5)
       ≥College degree33.5 (31.1, 36.1)38.2 (35.6, 40.8)2.6 (1.8, 3.6)25.7 (23.3, 28.3)
      Household income**
       <$15K27.6 (22.8, 32.9)35.2 (29.8, 41.0)7.9 (5.0, 12.2)29.4 (24.4, 34.9)
       $15K–$24.9K23.6 (18.5, 29.7)36.8 (30.3, 43.8)4.7 (2.0, 10.6)34.9 (28.7, 41.5)
       $25K–$39.9K27.6 (23.8, 31.8)38.9 (34.6, 43.4)4.8 (3.0, 7.4)28.7 (24.8, 32.9)
       $40K–$59.9K29.5 (26.0, 33.4)32.7 (29.1, 36.6)3.4 (2.0, 5.7)34.3 (30.5, 38.4)
       ≥$60K33.2 (31.1, 35.4)35.7 (33.5, 37.9)3.4 (2.5, 4.5)27.8 (25.7, 29.9)
      U.S. region
       Northeast32.5 (28.7, 36.5)36.3 (32.4, 40.4)3.2 (2.1, 4.8)28.0 (24.5, 31.9)
       Midwest30.9 (27.9, 34.0)34.2 (31.0, 37.5)4.3 (2.9, 6.5)30.6 (27.7, 33.7)
       South30.4 (27.9, 33.1)34.0 (31.4, 36.8)4.1 (2.9, 5.8)31.5 (28.8, 34.3)
       West29.5 (26.4, 32.8)39.2 (35.8, 42.6)4.7 (3.2, 6.8)26.7 (23.7, 29.8)
      E-cigarette use***
       Ever tried51.2 (47.3, 55.1)25.9 (22.6, 29.4)3.8 (2.4, 6.1)19.1 (16.3, 22.3)
       Never tried25.7 (24.1, 27.4)38.0 (36.2, 39.9)4.2 (3.4, 5.2)32.0 (30.3, 33.9)
      Note: Boldface indicates statistical significance (*p<0.05; **p<0.01; ***p<0.001). p is based on weighted bivariate tests of association (χ2).
      NH, non-Hispanic.
      Results of the multivariable multinomial logistic regression analysis showed that compared with 2012, the odds of perceiving e-cigarettes to be equally or more harmful (compared with less harmful) doubled (95% CI=1.64, 2.41, p<0.001) in 2014, and tripled (95% CI=2.60, 3.81, p<0.001) in 2015 (Table 3). Adults who perceived e-cigarettes to be addictive had a 4.30-fold (95% CI=3.22, 5.76, p<0.001) higher adjusted odds of perceiving e-cigarettes to be equally or more harmful than cigarettes. Significant differences were observed in perceived harmfulness of e-cigarettes by sex, age, and ever trying e-cigarettes. Compared with never e-cigarette users, adults who ever tried e-cigarettes had 61% reduction in the adjusted odds of perceiving e-cigarettes to be equally harmful or more harmful than cigarettes. Men were less likely than women to perceive e-cigarettes as equally or more harmful than cigarettes. Compared with young adults, those aged ≥25 years had higher odds of perceiving e-cigarettes as equally or more harmful than perceiving them to be less harmful than cigarettes.
      Table 3Factors Associated With Perceived Harmfulness of E-cigarettes Among U.S. Adults, 2012–2015
      Independent variablesCompared to cigarettes, smoking e-cigarettes is:
      Equally or more harmful,
      Analysis was performed using multivariable multinomial logistic regression; the response category “less harmful” was used as the reference group. All variables in the table were included as covariates.
      AOR (95% CI)
      I don’t know,
      Analysis was performed using multivariable multinomial logistic regression; the response category “less harmful” was used as the reference group. All variables in the table were included as covariates.
      AOR (95% CI)
      Survey year
       2012refref
       20141.99 (1.64, 2.41)***0.93 (0.81, 1.08)
       20153.15 (2.60, 3.81)***1.01 (0.86, 1.17)
      Perception of addictiveness
       Norefref
       Yes4.30 (3.22, 5.76)***2.46 (1.79, 3.40)***
       I don’t know1.38 (1.02, 1.88)*6.20 (4.49, 8.55)***
      E-cigarette use
       Never triedrefref
       Ever tried0.39 (0.33, 0.46)***0.37 (0.31, 0.45)***
      Sex
       Male0.66 (0.59, 0.73)***0.75 (0.67, 0.84)***
       Femalerefref
      Age (year)
       18–24refref
       25–341.38 (1.08, 1.75)**1.00 (0.78, 1.28)
       35–441.37 (1.08, 1.74)*1.38 (1.09, 1.74)**
       45–541.66 (1.30, 2.12)***1.76 (1.40, 2.22)***
       55–641.47 (1.15, 1.87)**1.85 (1.47, 2.33)***
       ≥651.77 (1.38, 2.26)***2.24 (1.77, 2.83)***
      Smoking status
       Current smoker1.33 (1.10, 1.60)**1.31 (1.10, 1.56)**
       Former smoker0.97 (0.84, 1.11)1.18 (1.03, 1.34)*
       Never smokerrefref
      Note: Boldface indicates statistical significance (*p<0.05; **p<0.01; ***p<0.001).
      a Analysis was performed using multivariable multinomial logistic regression; the response category “less harmful” was used as the reference group. All variables in the table were included as covariates.
      No significant differences were observed in perceived addictiveness between men and women (Appendix Table 2, available online). However, the perception that e-cigarettes were non-addictive was more common among adults aged 25–34 years (7.2%, 95% CI=5.3, 9.7); those who were Hispanic (8.0%, 95% CI=5.5, 11.3); and those who had less than high school education (5.5%, 95% CI=3.1, 9.6). Compared with never users of e-cigarettes, those who have ever tried e-cigarettes were more likely to perceive e-cigarettes to be non-addictive (2.5%, 95% CI=1.9, 3.3 vs 8.9%, 95% CI=7.0, 11.2; p<0.001).

      Discussion

      The main goal of the present study was to determine whether the perceived relative harm of e-cigarettes versus combustible cigarettes changed between 2012 and 2015. Over this period, there was an increase in perceiving e-cigarettes to be equally or more harmful than cigarettes. Similarly, the belief that e-cigarettes are addictive increased among U.S. adults in 2012–2015. Adults who perceived e-cigarettes to be addictive, had never used e-cigarettes, were female, or aged 25–34 years were more likely to misperceive the harm of e-cigarettes—to believe that e-cigarettes are equally or more harmful than combustible cigarettes.
      The findings of the current study indicate that, over time, U.S. adults, irrespective of smoking history, increasingly believe that e-cigarettes could be as harmful as combustible cigarettes, a result congruent with the literature related to the public perceptions of relative harm of e-cigarettes.
      • Kiviniemi M.T.
      • Kozlowski L.T.
      Deficiencies in public understanding about tobacco harm reduction: results from a United States national survey.
      • Tan A.S.L.
      • Bigman C.A.
      E-cigarette awareness and perceived harmfulness. Prevalence and associations with smoking-cessation outcomes.
      • Brose L.S.
      • Brown J.
      • Hitchman S.C.
      • McNeill A.
      Perceived relative harm of electronic cigarettes over time and impact on subsequent use. A survey with 1-year and 2-year follow-ups.
      A longitudinal study among British adult smokers documented a rise in perceiving e-cigarettes to be equally harmful to combustible cigarettes from 9.0% in 2012 to 16.9% in 2014.
      • Brose L.S.
      • Brown J.
      • Hitchman S.C.
      • McNeill A.
      Perceived relative harm of electronic cigarettes over time and impact on subsequent use. A survey with 1-year and 2-year follow-ups.
      Previous studies have shown that lower risk perceptions of e-cigarettes relative to combustible cigarettes are associated with ever trying and current use of e-cigarettes among adults,
      • Pokhrel P.
      • Fagan P.
      • Kehl L.
      • Herzog T.A.
      Receptivity to E-cigarette marketing, harm perceptions, and e-cigarette use.
      • Wackowski O.A.
      • Delnevo C.D.
      Young adults’ risk perceptions of various tobacco products relative to cigarettes: results from the National Young Adult Health Survey.
      future use among never users,
      • Brose L.S.
      • Brown J.
      • Hitchman S.C.
      • McNeill A.
      Perceived relative harm of electronic cigarettes over time and impact on subsequent use. A survey with 1-year and 2-year follow-ups.
      and exclusive e-cigarette use among smokers who have completely switched from combustible cigarettes.
      • Farsalinos K.E.
      • Romagna G.
      • Voudris V.
      Factors associated with dual use of tobacco and electronic cigarettes: a case control study.
      Higher risk perceptions of e-cigarettes could deter current smokers from using e-cigarettes as a cessation aid of smoking combustible cigarettes and preventing a potential public health benefit. Therefore, the observed trend is of particular importance and warrants further attention.
      The finding that the higher percentages of adults, including current smokers, misperceived e-cigarettes to be equally or more harmful than cigarettes between 2012 and 2015 may be stemming from misinformed media stories.

      Knapton S. E-cigarettes are no safer than smoking tobacco, scientists warn. The Telegraph. www.telegraph.co.uk/news/health/news/12073221/E-cigarettes-are-no-safer-than-smoking-tobacco-scientists-warn.html. Published December 29, 2015. Accessed January 15, 2016.

      Toxicology studies on the biological effects of e-cigarette aerosol on the respiratory, cardiovascular, and immune systems have provided evidence of the risk of e-cigarette use,
      • Breland A.
      • Soule E.
      • Lopez A.
      • et al.
      Electronic cigarettes: what are they and what do they do?.
      but the absolute level of exposure to risk is almost always significantly less than the exposure from combusted cigarettes. For example, one study examined the effect of e-cigarettes and combustible cigarettes on serum cotinine and lung function in 15 smokers and 15 non-smokers, and documented that short-term use of e-cigarettes may have a negative effect on lung function, but that the magnitude of the damage is much smaller than that of combustible cigarettes.
      • Flouris A.D.
      • Chorti M.S.
      • Poulianiti K.P.
      • et al.
      Acute impact of active and passive electronic cigarette smoking on serum cotinine and lung function.
      Another study found that the levels of toxicant and carcinogen metabolites in urine of exclusive e-cigarette users were lower than those in the urine of combustible cigarette smokers,
      • Hecht S.S.
      • Carmella S.G.
      • Kotandeniya D.
      • et al.
      Evaluation of toxicant and carcinogen metabolites in the urine of e-cigarette users versus cigarette smokers.
      thus supporting the view that e-cigarettes are less harmful than combustible cigarettes.
      • Nutt D.J.
      • Phillips L.D.
      • Balfour D.
      • et al.
      Estimating the harms of nicotine-containing products using the MCDA approach.
      At the same time, exposure to e-cigarette vapor was linked to DNA damage, suggesting that e-cigarette use may raise the risk of cancer.
      • Yu V.
      • Rahimy M.
      • Korrapati A.
      • et al.
      Electronic cigarettes induce DNA strand breaks and cell death independently of nicotine in cell lines.
      Findings of this study36 were highlighted in a media article in which e-cigarettes were presumed to be “no safer than smoking.”

      Knapton S. E-cigarettes are no safer than smoking tobacco, scientists warn. The Telegraph. www.telegraph.co.uk/news/health/news/12073221/E-cigarettes-are-no-safer-than-smoking-tobacco-scientists-warn.html. Published December 29, 2015. Accessed January 15, 2016.

      • Yu V.
      • Rahimy M.
      • Korrapati A.
      • et al.
      Electronic cigarettes induce DNA strand breaks and cell death independently of nicotine in cell lines.
      Confusing relative risk with absolute risk of e-cigarettes may contribute to framing bias
      • Gordon-Lubitz R.J.
      Risk communication: problems of presentation and understanding.
      in risk communication and result in media reports and press releases in which the scientific evidence of absolute harm is highlighted and that of relative harm is overlooked. Objective findings may be obscured by the overall image and tone of the news story,
      • Slovic P.
      The Feeling of Risk: New Perspectives on Risk Perceptions.
      negatively influencing public perceptions of e-cigarettes.
      Another explanation for the increasingly high perceived risk of e-cigarettes in comparison with combustible cigarettes could be related to the frequent reports of adverse incidents associated with e-cigarette use. Extensive reporting of adverse events has been shown to contribute to public concerns.
      • Slovic P.
      The Feeling of Risk: New Perspectives on Risk Perceptions.
      Recent media reports linking e-cigarettes and e-liquid to serious injuries,

      Mohney G. First child’s death from liquid nicotine reported as “vaping” gains popularity. ABC News. http://abcnews.go.com/Health/childs-death-liquid-nicotine-reported-vaping-gains-popularity/story?id=27563788. Published December 12, 2014. Accessed January 20, 2016.

      Ng A. E-cigarette explosion breaks Memphis native’s neck, almost paralyzes him for life. New York Daily News. www.nydailynews.com/news/national/e-cigarette-explosion-breaks-man-neck-paralyzes-article-1.2444620. Published November 23, 2015. Accessed June 1, 2016.

      exposure to toxicants,

      Brazier Y. E-cigarettes impair immune responses more than tobacco. Medical News Today. www.medicalnewstoday.com/articles/306444.php. Published February 15, 2016. Accessed Feruary 15, 2016.

      development of lung diseases,

      Winter L. E-cigarette vapor shown to repress immune system. Health Med. www.iflscience.com/health-and-medicine/e-cigarette-vapor-shown-repress-immune-system. Published 2015. Accessed February 20, 2016.

      and other health related problems

      Colbert T. Approach with caution: taking a critical look at vaping and e-cigarette trends. Los Angeles Times. www.latimes.com/brandpublishing/localplus/ucsandiego/la-ss-ucsd2015-vaping-dto-story.html. Published September 25, 2015. Accessed February 20, 2016.

      may have contributed to the increasing trend of equating the harm of e-cigarettes to traditional cigarettes. Lastly, U.S. adults may be partially equating the harm of e-cigarettes to combustible cigarettes owing to other concerns related to the potential of e-juice flavors to lure children into addiction,
      • Cardenas V.M.
      • Evans V.L.
      • Balamurugan A.
      • et al.
      Use of electronic nicotine delivery systems and recent initiation of smoking among U.S. youth.

      DePinho RA. It’s time to regulate America’s latest addiction. The Huffington Post. www.huffingtonpost.com/ronald-a-depinho-md/its-time-to-regulate-amer_b_6672008.html. Published February 12, 2015. Accessed July 15, 2016.

      the use of e-cigarettes with illicit drugs,

      Silverman JR. E-cigarettes packed with marijuana oil set to boom in Colorado. New York Daily News. www.nydailynews.com/news/national/pot-boom-e-cigs-sales-set-soar-colo-article-1.1567304. Published January 6, 2014. Accessed February 20, 2016.

      and the concern that their use could renormalize smoking.
      • Cataldo J.K.
      • Petersen A.B.
      • Hunter M.
      • Wang J.
      • Sheon N.
      E-cigarette marketing and older smokers: road to renormalization.
      Future research should examine the role of such issues in shaping individual perceptions about e-cigarettes. The findings underscore the urgent need to convey accurate information to the public, especially adult smokers, about the available scientific evidence of the harm of e-cigarettes compared with combustible cigarettes. Public health messages should strike a balance between addressing the reduced harm of e-cigarettes compared with combustible cigarettes and presenting an accurate interpretation of the absolute harm of e-cigarette use.
      In the current study, the estimated percentages of adults who thought e-cigarettes were less harmful than cigarettes were lower than those documented in previous studies.
      • Kiviniemi M.T.
      • Kozlowski L.T.
      Deficiencies in public understanding about tobacco harm reduction: results from a United States national survey.
      • Wackowski O.A.
      • Delnevo C.D.
      Young adults’ risk perceptions of various tobacco products relative to cigarettes: results from the National Young Adult Health Survey.
      • Brown J.
      • West R.
      • Beard E.
      • et al.
      Prevalence and characteristics of e-cigarette users in Great Britain: Findings from a general population survey of smokers.
      This difference may be the result of variation in measures of perceived harm of e-cigarettes and in the characteristics of the study population. A study among a national sample of U.S. adults conducted in 2012–2013 revealed that 51.0% of adults perceived e-cigarettes to be less harmful than cigarettes.
      • Kiviniemi M.T.
      • Kozlowski L.T.
      Deficiencies in public understanding about tobacco harm reduction: results from a United States national survey.
      In that study, perception of relative harm was measured using a Likert scale question (1, much less risk; 5, much more risk).
      • Kiviniemi M.T.
      • Kozlowski L.T.
      Deficiencies in public understanding about tobacco harm reduction: results from a United States national survey.
      In the current study, perceived relative harm was measured using a four-response item (less harmful, about the same, more harmful, I don’t know). Allowing participants to choose an I don’t know response may explain the lower percentage of adults who believed that e-cigarettes were less harmful than cigarettes. Furthermore, differences in population characteristics, such as differences in age or smoking status, may explain why the observed percentages of perceiving e-cigarettes to be less harmful were lower than those detected in other studies,
      • Wackowski O.A.
      • Delnevo C.D.
      Young adults’ risk perceptions of various tobacco products relative to cigarettes: results from the National Young Adult Health Survey.
      • Brown J.
      • West R.
      • Beard E.
      • et al.
      Prevalence and characteristics of e-cigarette users in Great Britain: Findings from a general population survey of smokers.
      despite using the same measurement.
      Although the current study provides no information on the level of addictiveness of e-cigarettes compared with combustible cigarettes, the data show that U.S. adults hold the correct view about the addictive nature of e-cigarettes. Most e-cigarettes deliver nicotine, an addictive chemical, though with actual nicotine exposure dependent on product design and user behavior.
      • Breland A.
      • Soule E.
      • Lopez A.
      • et al.
      Electronic cigarettes: what are they and what do they do?.
      In May 2016, e-cigarettes were deemed to be regulated by the U.S. Food and Drug Administration; under this rule, e-cigarettes with nicotine are required to carry an addiction warning statement.
      Deeming tobacco products to be subject to the Federal Food, Drug, and Cosmetic Act, as amended by the Family Smoking Prevention and Tobacco Control Act; restrictions on the sale and distribution of tobacco products and required warning statements for tobacco products. Final rule.
      Future research examining how the public perceive the addictive nature of e-cigarettes is warranted to evaluate the effectiveness of the new rule of subjecting e-cigarettes to the addiction warning statement.

       Limitations

      The use of an online research panel (KnowledgePanel) may raise concerns about generalizability of the results to the U.S. adult population. In addition, the rapid changes of e-cigarette design, characteristics, and nomenclature make it difficult to identify accurate terminology to develop questions regarding e-cigarette awareness, use, and perceptions of harm and addictiveness. Whereas in 2012 and 2014 surveys the term “e-cigarette” was used to describe the product, a different wording was used in the 2015 survey, “electronic vapor product,” to provide an updated terminology that encompasses newer models. This variation in wording may raise concerns about comparability across years. However, the three surveys assessed perceptions of harm using the same question and the same response categories. Finally, similar to previous studies,
      • Kiviniemi M.T.
      • Kozlowski L.T.
      Deficiencies in public understanding about tobacco harm reduction: results from a United States national survey.
      • Tan A.S.L.
      • Bigman C.A.
      E-cigarette awareness and perceived harmfulness. Prevalence and associations with smoking-cessation outcomes.
      • Brose L.S.
      • Brown J.
      • Hitchman S.C.
      • McNeill A.
      Perceived relative harm of electronic cigarettes over time and impact on subsequent use. A survey with 1-year and 2-year follow-ups.
      one general question to measure the perceived relative harm was used, which may not capture various aspects of harm.
      • Pepper J.
      • Emery S.
      • Ribisl K.
      • Rini C.
      • Brewer N.
      How risky is it to use e-cigarettes? Smokers’ beliefs about their health risks from using novel and traditional tobacco products.

      Conclusions

      The results document an increase in the misperception that e-cigarettes are equally or even more harmful than combustible cigarettes. The study highlights the need to design public health messages that accurately interpret the scientific data on the potential harm of e-cigarette use and clearly differentiate the absolute from the relative harm of e-cigarettes.

      Acknowledgments

      The authors acknowledge Rachel Lawley and Dr. Richard Rothenberg from the School of Public Health, Georgia State University, for their invaluable help in the production of this manuscript.
      This work was supported by the Georgia Cancer Coalition (SP000ELM76) and by Grant Number P50DA036128 from NIH, National Institute of Drug Abuse, and U.S. Food and Drug Administration, Center for Tobacco Products. The content is solely the responsibility of the authors and does not necessarily represent the official views of NIH or the U.S. Food and Drug Administration.
      Drs. Pechacek and Eriksen receive unrestricted research funding support from Pfizer, Inc. (“Diffusion of Tobacco Control Fundamentals to Other Large Chinese Cities,” Michael Eriksen, Principal Investigator). No financial disclosures were reported by the other authors of this paper. The authors declare that there are no other financial relationships with any organizations that might have an interest in the submitted work, particularly electronic cigarette companies, and there are no other relationships or activities that could appear to have influenced the submitted work.

      Supplementary material

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