Vaping is the inhaling of aerosol (chemicals) from heated liquids using electronic delivery systems. This is a colloquial term used to describe the habit as it involves inhaled vapours (aerosol) from heated liquids in the device. This alternative to cigarette smoking appeared in the mid-2000s and was believed to reduce the risk of inhaling carcinogens and other toxins associated with cigarette smoking.¹ These devices are often composed of a battery, an atomiser and a cartridge containing liquids called e-liquids, enclosed in a metal container with a mouthpiece (see Figure 1). The most common psychoactive substance in these e-liquids is nicotine, hence the name electronic nicotine delivery systems (ENDS). The alternative without nicotine is called electronic non-nicotine delivery systems (ENNDS) and may contain other psychoactive substances such as cannabis. In some instances, these e-liquids are nicotine-less flavours that were previously marketed as entirely harmless. This assertion and the gap in legislation about marketing these products when they were first introduced to markets were exploited to market the products to vulnerable populations.² The Tobacco Products Control Amendment Act 63 of 2008 that governs tobacco use in South Africa (SA) predates the era of e-cigarettes. This law directly restricts the sale of tobacco products to minors, prohibits advertising of these products, and includes increased taxation on these products. South Africa has implemented the Framework Convention on Tobacco Control using the MPOWER initiative recommended by the World Health Organization (WHO) (a technical package of tobacco demand reduction).³ In 2022, a bill was introduced in the South African parliament, specifically mentioning electronic devices. It has the potential to limit exposure of children and adolescents to the sale of ENDS and ENNDS.⁴

The electronic cigarette, in its current battery-operated form, was first invented by a Chinese pharmacist, Hon Lik.⁵ His motivation was to develop a device that would help him stop a heavy smoking habit. He had watched his father struggle with lung diseases due to smoking. In the past 100 years, many similar ideas were developed, but the current invention dates to 2003.⁶

The use of ENDS was initially marketed as a less harmful means of tobacco use. It was essentially introduced by tobacco companies as a means for tobacco harm reduction. It was marketed originally to assist persons with nicotine addiction in stopping the habit and was marketed as such, a less harmful means of delivering nicotine to these clients. It was considered a more appealing way to access nicotine and was marketed increasingly not only to adults trying to quit smoking but also to adolescents and young adults who viewed it as less harmful.^8,9 The public health impact of smoking made this rather easy, as it was perceived as less harmful to the environment and believed not to be associated with secondary smoking. Electronic nicotine delivery systems have since become widely used to access nicotine, a highly addictive substance, and are increasingly used by adolescents and young adults.^10,11

Although e-cigarettes are generally considered less harmful than traditional cigarettes, two decades after their introduction to international markets, there is growing concern that increasing numbers of young people who have never used tobacco are now taking up these products.^12,13

In preparing this continuing medical education subject, the authors appraised review articles, population surveys, and reports of expert opinions on the effect of e-liquids and e-cigarettes on human health. The trends show use of ENDS among persons seeking to stop harmful use of tobacco products, as well as adolescents and young adults who are curious about the novelty of e-cigarettes and the many flavours of e-liquids.^14,15 A morbidity and mortality survey report from the United States in 2024 revealed 5.4% of students in middle and high school used e-cigarettes.¹¹ It is believed that there is a higher awareness of vaping in these populations than in low- and middle-income country (LMIC) populations.¹² The findings of a self-administered survey among South African students reported that 16.83% of over 25 000 students across 52 schools were actively vaping. In the same study, more than one-third of participants reported having used the device at some point. Curiosity and social influences were the most common reasons for initiating use, while continued use was mainly attributed to enjoyment and stress relief.¹³ These findings suggest the challenges of increasing exposure among adolescents and young adults who were never cigarette smokers and the potential for ENDS & ENNDS to be a ‘gateway’ to nicotine addiction and potentially other psychoactive substances such as cannabis.

The WHO factsheet flags e-cigarettes as harmful to human health; there is no substantive evidence of their usefulness in combatting nicotine addiction.¹⁶ The paucity of directed policies to control marketing of these products when they were first introduced to markets left a gap in legislation, allowing these products to be marketed as safe alternatives to smoking. The effect of this gap is that a larger population of consumers of these products started out experimenting and became established users of these products as a gateway to smoking cigarettes.¹ A telephonic survey conducted in SA in 2022 similarly revealed the potential of these products for helping with tobacco harm reduction but also being a potential gateway to smoking and the use of other tobacco products.¹⁷ A Cochrane database systematic review published in 2021 included 61 studies (34 randomised controlled trials) and surmised that ENDS were potentially more useful in helping longstanding cigarette smokers quit nicotine addiction when compared to other adjuncts for therapy.¹⁸

In the early days, there was limited knowledge about the potential impact of these electronic devices on human health, and so the rapid uptake across many countries. A critical umbrella review in 2023 by authors across Europe, the Americas, Australia and North Africa found e-cigarettes are useful in reducing cigarette smoking.¹⁹ However, another meta-analysis of randomised controlled trials was inconclusive as it included very small population studies which were not powered to give conclusive evidence.²⁰ A South African-authored narrative review of South African papers describes a widespread use of e-cigarettes and highlights the benefits of legislation that controls the sale of e-cigarettes similar to other tobacco products.²¹ There is a paucity of studies on the use of e-cigarettes for tobacco harm reduction in the South African population.

In 2016, the WHO published recommendations for tobacco control highlighting emerging reports of the harmful effects of these products and their impact on cardiovascular and respiratory health.²² A bill was presented in parliament in 2022 that would address most concerns expressed by clinical experts to restrict access to ENDS and ENNDS like other tobacco products. This bill has not yet been passed.⁴ The legislation in SA does not provide restrictions on the marketing and use of ENDS and ENNDS.

The inhalation of aerosolised liquids containing ultra-fine particles that are potentially toxic is now described through case reports, surveys and toxicology reports.^23,24 These particles, depending on the type, affect various aspects of the human body. An overview of the effects of e-cigarettes based on human and laboratory studies reveals the potentially toxic nature of heating all components of the e-cigarette²⁵ (see Table 1).

A lot remains unknown about the health effects of e-cigarettes. Toxicology experts have identified known toxins associated with these devices. Evolving evidence suggests that e-cigarettes are less harmful than the known effects of cigarette smoking. However, not much is known about the long-term effects of e-cigarettes.

Studies in the last two decades have focused on e-liquids because they are aerosolised and in direct contact with human tissue (inhaled or deposited on surfaces as ECEAR). Not much is known about the effects of the materials used in the other components of the e-cigarette. Although they were introduced as devices to reduce the harmful effects of tobacco smoking, they were marketed by manufacturers as less harmful. The widespread use among adolescents and young adults who were not previously cigarette smokers has raised interest in their potential as a ‘gateway’ to using addictive psychoactive substances such as nicotine and cannabis. It is still unknown what the public health implications are for young adolescents gaining access to these devices so early in life and the potential harms in later years. Primary care clinicians should routinely screen for the use of e-cigarettes and related devices, alongside established questions about alcohol, illicit drugs and cigarette smoking. Identifying use enables clinicians to consider potential adverse effects in the differential diagnosis and, when appropriate, refer patients to respiratory medicine specialists who are better equipped to manage these complications.

Research on e-cigarettes for tobacco harm reduction is largely conducted in high-income countries (HICs), with little to none found in LMICs; there is evidence to support their use in breaking nicotine addiction. It is still unclear what pattern of tobacco harm reduction is used across many LMICs for tobacco harm reduction. Studies in South Africa show that many more adolescents use these devices, as described in HICs. Nonetheless, further research is still required to determine the true potential of e-cigarettes in tobacco harm reduction and the long-term effects of use on the health of populations in LMICs.