Lifestyle and exercise

Are e-cigarettes a 'gateway to nicotine addiction'?

"E-cigarettes are encouraging a new generation to become hooked on nicotine," reports the Mail Online.

E-cigarettes are devices that deliver a heated aerosol ("vapour") of nicotine in a way that mimics conventional cigarettes. But they have lower levels of toxins such as tar than a conventional tobacco cigarette. They are marketed as a safer alternative to regular smoking, or as a way to quit.

Today's headlines followed a survey of thousands of US teenagers (who were under 15 on average, meaning that those who smoked cigarettes were underage).

It found that those who had tried e-cigarettes were more likely to have smoked conventional cigarettes and less likely to be abstaining from conventional smoking than those who hadn't tried e-cigarettes.

However, it also found those who tried e-cigarettes were more likely to want to quit conventional smoking.

On average tobacco smokers die significantly younger and spend more of their shorter lives ill. Because e-cigarettes can be marketed to young people, there is a worry that if they did lead to more conventional smoking, they could have a potentially disastrous impact on public health.

This current study does suggest that e-cigarettes may not be the harmless alternative some believe, and may be acting as a "gateway drug" to conventional smoking.

However, it does not prove that is the case. It is quite plausible that existing teenage smokers are also trying e-cigarettes for a variety of reasons.

The debate about the safety and regulation of e-cigarettes is likely to continue until more robust long-term evidence emerges.

Where did the story come from?

The study was carried out by researchers from the Center for Tobacco Research and Education at the University of California, San Francisco, and was funded by the US National Cancer Institute.

It was published in the peer-reviewed medical journal, JAMA Pediatrics.

The Mail Online coverage was balanced and discussed the pros and cons of e-cigarettes. It also usefully brought in some wider research from 75,000 Korean adolescents "which also found that adolescents who used e-cigarettes were less likely to have stopped smoking conventional cigarettes".

What kind of research was this?

This was a cross-sectional study looking at whether e-cigarette use was linked to conventional cigarette smoking behaviour among US adolescents.

E-cigarettes are devices that deliver a heated aerosol of nicotine in a way that mimics conventional cigarettes while delivering lower levels of toxins, such as tar, than a conventional combusted cigarette. They are often marketed as a safer alternative to regular smoking, or as a way of helping people quit traditional smoking.

The devices are not currently regulated in the US or the UK, meaning there are limited or vague rules concerning appropriate advertising. The researchers say e-cigarettes are being aggressively marketed using the same messages and media channels that cigarette companies used to market conventional cigarettes in the 1950s and 1960s. These include targeting young people to get a new generation of smokers hooked on nicotine for life.

The researchers outline how studies have demonstrated that youth exposure to cigarette advertising causes youth smoking. Meanwhile, electronic cigarettes can be sold in flavours such as strawberry, liquorice or chocolate, which are banned in cigarettes in the US because they appeal to youths.

Given the potential for a new generation to be hooked on nicotine and then tobacco smoking in this unregulated environment, the researchers wanted to investigate whether e-cigarettes were associated with regular smoking behaviour in adolescents.

What did the research involve?

The researchers used existing smoking data collected from US middle and high school students in 2011 (17,353 students) and 2012 (22,529) during the large US National Youth Tobacco Survey. They analysed whether use of e-cigarettes was linked with conventional tobacco smoking and smoking abstinence behaviour.

The National Youth Tobacco Survey was described as an anonymous, self-administered, 81-item, pencil-and-paper questionnaire that included:

  • indicators of tobacco use (cigarettes, cigars, smokeless tobacco, kreteks [southeast Asian clove cigarettes], pipes, and "emerging" tobacco products)
  • tobacco-related beliefs
  • attitudes about tobacco products
  • smoking cessation
  • exposure to secondhand smoke
  • ability to purchase tobacco products
  • exposure to pro-tobacco and anti-tobacco influences

Smoking behaviour was categorised as:

  • conventional cigarette experimenters – adolescents who responded "yes" to the question "Have you ever tried cigarette smoking, even one or two puffs?"
  • ever-smokers of conventional cigarettes – those who replied "100 or more cigarettes (five or more packs)" to the question "About how many cigarettes have you smoked in your entire life?"
  • current smokers of conventional cigarettes – those who had smoked at least 100 cigarettes and smoked in the past 30 days
  • ever e-cigarette users – adolescents who responded "electronic cigarettes or e-cigarettes, such as Ruyan or NJOY" to the question "Which of the following tobacco products have you ever tried, even just one time?"
  • current e-cigarette users – those who responded "e-cigarettes" to the question "During the past 30 days, which of the following tobacco products did you use on at least one day?"

Data on intention to quit smoking in the next year, previous quit attempts and abstinence from conventional cigarettes was also collected. The analysis was adjusted for potential confounding factors such as race, gender and age.

What were the basic results?

The main analysis included 92.0% of respondents (17,353 of 18,866) in 2011 and 91.4% of respondents (22,529 of 24,658) in 2012 who had complete data on conventional cigarette use, e-cigarette use, race, gender and age. The mean age was 14.7, and 5.6% of respondents reported ever or current conventional cigarette smoking (of these, 5% currently smoked).

In 2011, 3.1% of the study sample had tried e-cigarettes (1.7% dual ever use, 1.5% only e-cigarettes) and 1.1% were current e-cigarette users (0.5% dual use, 0.6% only e-cigarettes).

In 2012, the 6.5% of the sample had tried e-cigarettes (2.6% dual use, 4.1% only e-cigarettes) and 2.0% were current e-cigarette users (1.0% dual use, 1.1% only e-cigarettes).

Ever e-cigarette users were significantly more likely to be male, white and older. The rates of ever-tried e-cigarettes and current e-cigarette smoking approximately doubled between 2011 and 2012.

The main analysis found use of e-cigarettes was significantly associated with:

  • higher odds of ever or current cigarette smoking
  • higher odds of established smoking
  • higher odds of planning to quit smoking among current smokers
  • among e-cigarette experimenters, lower odds of abstinence from conventional cigarettes

How did the researchers interpret the results?

The researchers' interpretation was clear: "Use of e-cigarettes does not discourage, and may encourage, conventional cigarette use among US adolescents."

They added that, "In combination with the observations that e-cigarette users are heavier smokers and less likely to have stopped smoking cigarettes, these results suggest that e-cigarette use is aggravating rather than ameliorating the tobacco epidemic among youths. These results call into question claims that e-cigarettes are effective as smoking cessation aids."


This study found US adolescents who use e-cigarettes are more likely to smoke conventional cigarettes. They also have lower odds of abstaining from conventional cigarettes than those who don't try e-cigarettes. On the flip side, e-cigarette users were more likely to report planning to quit conventional smoking.

The research sample was large, so is likely to provide a relatively accurate picture of the smoking behaviour of US adolescents.

These results suggest that e-cigarettes may not discourage conventional cigarette smoking in US adolescents, and may encourage it. However, because of the cross-sectional nature of the information, it cannot prove that trying e-cigarettes causes adolescents to take up conventional smoking. There may be other factors at play.

And indeed, smoking tobacco cigarettes may cause teenagers to take up e-cigarettes. For example, the type of person who may want to try smoking in the past could only try conventional smoking. Nowadays, they have e-cigarettes as an option too.

Retrospectively trying to work out if they would have taken up conventional smoking had they not tried e-cigarettes first is not possible. This question would require a cohort study that tracks behaviour over time. You would then be able to see which smoking method they took up first and if one led to the other. This was not possible using the data the researchers had to hand in the current study.

Conventional smoking has been a public health priority for many decades because, on average, smokers die significantly younger (more than a decade in some groups) and they spend more of their shorter lives ill. Consequently, any product that may increase the rates of conventional smoking among the young – such as e-cigarettes – has serious and widespread health consequences.

Currently, regulation around e-cigarettes is minimal, but there are plans to introduce stricter rules in the UK. In the meantime, this study provides some evidence that e-cigarettes may not be the harmless, safe alternative some believe, and may be acting as a gateway drug to conventional smoking.

The research stops short of proving this, so the debate on whether e-cigarettes should be treated similarly to conventional cigarettes, through advertising and sales restrictions, is likely to continue.

NHS Attribution