INTRODUCTION
Electronic cigarettes (e-cigarettes) are a recent innovation. In 2003, the e-cigarette was invented by a Chinese pharmacist, and by 2010 several brands were established in the United States market1. Although three generations of e-cigarette designs have emerged over time, the basic components of e-cigarettes include: a battery, a reservoir for holding an e-juice (a solution that usually contains nicotine, flavorants, and propylene glycol and/or glycerin as a solvent), a heating element, and a mouthpiece. Specifically, the battery powers the heating element to heat the e-juice into an aerosol, which is then inhaled through the mouthpiece1.
E-cigarettes are growing in popularity, especially among adolescents and young adults in the United States. In 2015, a total of 24% of high school students had used e-cigarettes at least one time in the past 30 days2, a 900% increase1 since 2011. Moreover, data from the 2013–2014 National Adult Tobacco Survey indicated that 13% of young adults, age 18 to 24 years, were current users. The prevalence of e-cigarette use among these age groups resulted in a major report and call for action by the United States Surgeon General1.
The public health concern regarding e-cigarettes has typically focused on the chemicals that are potentially harmful (e.g. aerosols, formaldehyde, acetaldehyde, carcinogens, nicotine)1, however, another health issue is bodily harm caused by e-cigarettes that explode3. Although the cause of these explosions has not been fully determined3, previous incidents suggest that overheating of the battery (also known as ‘thermal runaway’) may lead to explosions4,5, which has also explained the explosions observed from other devices using lithium-ion batteries (e.g. smart phones, laptops)6. From 2009 to 2016, there were 195 e-cigarette explosions in the United States reported by the media, resulting in 133 injuries, with burns the most common injury4. Moreover, in 2016 alone, an estimated 1007 e-cigarette burn injuries were treated in emergency departments across the United States7.
It is also worth noting that besides burns, other cases of e-cigarette explosions involved a variety of serious injuries. Such injuries were inflicted to the hands8,9, face10, eyes11-13, mouth (e.g. lacerations, broken/missing t eeth)8,11,14-20, and also resulted in broken neck bones21. In addition, the first-ever death from an e-cigarette explosion was reported in 2018, which was due to e-cigarette shrapnel entering the person’s brain22.
Given the prevalence of e-cigarette explosions, there is a need for a comprehensive review of published case reports in peer-reviewed journals regarding injuries, especially burns. Although previous studies have reviewed the literature regarding burns caused by e-cigarette explosions, these reviews were not exhaustive of the literature23-26 , or focused only on explosion injuries reported by the media (e.g. online news, television, blogs)4,27 instead of on the scientific literature. In addition, these reviews have been disseminated through journals that are meant for physicians specializing in burn injuries, as opposed to health professionals dealing with tobacco prevention and cessation. As such, the purpose of this study was to provide a systematic review of published medical case reports of burn injuries caused by e-cigarette explosions in peer-reviewed journals.
METHODS
Articles were identified by using a comprehensive list of search terms and relevant databases. During January 2018, the Cumulative Index to Nursing and Allied Health Literature (CINAHL) and PubMed were searched using common terms regarding e-cigarettes (electronic cigarette, e-cigarette, vape, vaping, electronic nicotine delivery systems) and in every combination with the term ‘explosion’. To locate additional articles, ‘berry picking’ methods of ‘backward chaining’ (searching through the reference pages of relevant articles) and also ‘forward chaining’ (searching the studies that cited relevant articles)28 were used in Web of Science and Google Scholar29,30.
The resulting articles were included in the literature review based on the following eligibility criteria: written in English, described case reports of burn injuries caused by e-cigarette explosions, published in peer-reviewed journals, and published in any year. Articles were excluded if they described injuries other than burns or burns that were due to reasons other than an explosion (i.e. burns from a hot e-cigarette battery that did not explode). The inclusion and exclusion of articles were documented by the recommended flow diagram of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)31.
The articles included in the review were then analyzed. Cases were categorized by demographics, location of the e-cigarette explosion, burned body areas, types of burns, total body surface area of burns, the need for skin grafting, and the length of hospital stay.
RESULTS
A total of 31 articles8,9,11,13,16-18,20,23,25-27,32-50 met the review’s inclusion criteria (Figure 1). These were published from 2015 to 2017 in a variety of medical journals. In all, the articles described 164 cases. The explosions took place in the United States, the United Kingdom, Canada, Germany, and France.
The cases varied in terms of demographics. The majority of patients (90%) were male. Of the reports that specified the patient’s age, there was a range in age from 16 to 63 years (M=1.3, Mdn=29, SD=10.5) and mostly were young (20 to 29 years) (Table 1).
Table 1
Demographics of e-cigarette explosion cases
| Demographics | Frequency (%) |
|---|---|
| Sex | |
| Male | 147 (90) |
| Female | 12 (7) |
| NA | 5 (3) |
| Age (years) | |
| 16–19 | 9 (5) |
| 20–29 | 38 (23) |
| 30–39 | 22 (13) |
| 40–49 | 14 (9) |
| 50–59 | 3 (2) |
| 60+ | 1 (<1) |
| NA | 77 (47) |
The cases also varied in terms of the location of the e-cigarette explosions and in the location and types of burn injuries. In the majority of cases (65%), e-cigarettes exploded in people’s pockets (Table 2). The most common injured body areas included the thigh, hand, genitals, and face (Table 2). Burn severity was typically second-degree (35%) and a combination of second-degree and third-degree burns (20%). Reports described 84 patients’ total body surface area (TBSA) burns, which ranged from 0.5% to 27.25% (M=4.9, Mdn=4, SD=4.3) (Table 2). In all, 48 patients required skin grafting. Of the articles that described 19 patients’ length of stay in the hospital for treatment, the number of days ranged from 1 to 31 days (M=7.4, Mdn=5, SD=6.9).
Table 2
Location of e-cigarette explosions and description of burn injuries
Several reports included information regarding the context of the explosion (Table 3). Several cases reported the e-cigarette touching metallic objects (e.g. coins, car keys) in the pocket during the time of explosion. Others stated issues related to charging their e-cigarette battery. Explosions took place while e-cigarettes were being used or while being stored in users’ pockets.
Table 3
Precipitating events of e-cigarette explosion burn injuries
DISCUSSION
The primary aim of this study was to systematically review and synthesize evidence on case reports of burn injuries caused by e-cigarette explosions. A total of 31 studies reporting 164 patients were included in this systematic review, finding that e-cigarette explosions happened most often in pants pockets and among young men. The burn injuries were usually on the thighs and hands, and ranged in severity. To the best of our knowledge, this is the most comprehensive review on this topic. There are implications both in terms of public health prevention and future scientific research on this issue.
Although the scientific community is divided regarding the benefits or harms of e-cigarettes51,52, the findings from this literature review side directly with the potential harm of e-cigarettes, due to explosion injuries. The findings have important implications regarding regulation, public health advocacy, and education, as other experts have also emphasized53,54.
First and foremost, e-cigarette manufacturers should invest in research and development to improve the safety features of e-cigarette batteries. Brown and Cheng55 of the FDA’s Center for Tobacco Products have called for e-cigarette manufactures to investigate the unknown failure mechanisms and create standardized protocols for testing e-cigarettes. In addition, Brown and Cheng recommend that manufacturers prevent thermal runaway by using circuits that protect against overcharging, integrating cut-offs for thermal power, and using internal overpressure relief mechanisms55. By ensuring proper design in regard to safety, manufacturers can help to prevent e-cigarette explosions and consequent injuries.
Second, health professionals should advocate the regulation of e-cigarette batteries and the prohibition of e-cigarettes in areas that could cause major damage by explosions. For example, given the United States Food and Drug Administration’s (FDA) new authority over the packaging, labeling, and sale of e-cigarettes56, the FDA could mandate for e-cigarette retailers to provide information about potential explosions to customers. Voicing concern about e-cigarettes from a public health perspective is vital for the implementation of needed policy. In addition, it is important to advocate the prohibition of e-cigarettes in places where they are currently being used that could cause larger explosions and injuries, such as in airplanes57,58.
Third, the findings indicate that public health professionals and e-cigarette manufactures need to improve efforts to inform with regard to safe handling practices for e-cigarette batteries. Although the FDA has created a webpage dedicated to tips for avoiding explosions (e.g. use device specific batteries and chargers, replace batteries if damaged or wet, keep e-cigarettes away from metal objects, do not charge batteries overnight)3, research suggests that the FDA’s webpage is not among the most searched sites regarding e-cigarette batteries59. Manufacturer websites and information included with e-cigarette packaging are often lacking information about battery explosions or not providing credible material to users59. The results from our review suggest that this information should be targeted towards groups which experience e-cigarette injuries most often, such as young males.
Finally, information and images of the severity of e-cigarette explosion burns could be used as leverage for prevention efforts. Research indicates that fear appeals using graphic images can be effective in improving attitudes and changing health behaviors60,61. For instance, interventions that show images of smoking’s impact on premature facial wrinkles can instill motives for smoking cessation62-63. Research suggests that knowledge of e-cigarette explosions may deter young people from using e-cigarettes67,68. As such, public health professionals should consider using graphic images of e-cigarette explosion injuries in educational materials to prevent or reduce e-cigarette use.
Limitations
The limitations of this study should be considered when interpreting this review’s findings. First, it is obvious that the specific search terms and databases used in this review cannot be expected to locate every relevant published article. As such, the conclusions from the articles may not mirror all published research on this topic. Second, several of the studies did not include detailed information about each patient; therefore, the extent of all the patients’ burns may not exactly reflect that of the review’s findings. Finally, by only researching medical case studies, our findings do not cover people that experienced an explosion but did not visit a hospital for treatment.
CONCLUSIONS
This study was the first to systematically and thoroughly review published medical case reports on e-cigarette burn injuries. The severity of burns and the commonly injured locations (e.g. thigh, hands, genitals, face) strongly indicate a need for improved e-cigarette construction and for health professionals to advocate regulation of e-cigarette batteries, as well as insist on improved dissemination of information on explosions, for safety and prevention purposes.
