Last updated: October 2018
Suggested citation: Greenhalgh, EM, Jenkins, S, MacKenzie, R, & Scollo, MM. 18.4 Safety risks and abuse potential of e-cigarettes. In Greenhalgh, EM, Scollo, MM and Winstanley, MH [editors]. Tobacco in Australia: Facts and issues. Melbourne: Cancer Council Victoria; 2023. Available from: https://www.tobaccoinaustralia.org.au/chapter-18-e-cigarettes/18-5-safety-risks-and-abuse-potential-of-e-cigarettes
This section examines:
- Safety risks, including:
- Abuse potential, including:
- Environmental impact, including:
18.4.1 Safety risks
18.104.22.168 Explosions, fires and burns
As the popularity of e-cigarettes has increased, there have been growing reports of fires and burn injuries attributed to e-cigarette battery explosions.1-8 An analysis of e-cigarette explosion and burn injuries presenting to US hospital emergency departments (EDs) between 2015 and 2017 concluded that past reports appear to substantially underestimate the actual number of these events. It estimated that there were 2035 presentations over this period—between 15 and 40 times more than previous estimates. The true number of injuries also likely exceeds these estimates, given that people with less severe injuries are less likely to present to an ED.9
A 2017 review of burns associated with e-cigarette batteries found that the most frequent sites of injury involved the lower extremities and hands. Nearly half of the reported incidences required surgical management as a result of the depth of injury.1 An analysis of e-cigarette-related burns cases presenting to US emergency departments in 2016 found that most of the burns were thermal and occurred to the upper leg/lower trunk. Many occurred when the device was in users’ pockets.10 There have also been case reports of such explosions causing fractures11 and ocular injuries.12 A man was reportedly killed in late 2014 when a charging e-cigarette exploded and ignited his oxygen equipment.13
Following several fires, in 2015 the International Civil Aviation Organization prohibited airplane passengers and crew from carrying e-cigarettes and other battery-powered portable electronic smoking devices in checked baggage, and from recharging the devices in aircraft cabins.14
Although e-cigarette manufacturers have tended to attribute blame for explosions to the user for charging the devices improperly, a 2017 report from the US Fire Administration found that only 25 per cent of explosions occurred during the charging process. Sixty-two per cent of the devices exploded when being carried in a pocket or when they were actively in use. It notes that the shape and construction of e-cigarettes is itself problematic. Unlike other products such as mobile phones and laptops, e-cigarettes include cylindrical lithium-ion batteries installed in a cylindrical tube—one that is weakest at both ends. Battery failures generate increased pressure that “shoots” the batteries out of the tube like “rockets.” The report concludes that:
Lithium-ion batteries should not be used in e-cigarettes. While the number of batteries that explode and catch fire is statistically small, the catastrophic nature of the injuries that can occur warrants the use of another battery technology for e-cigarettes.15
22.214.171.124 Nicotine toxicity and accidental poisoning
The nicotine content of e-cigarettes typically ranges between 0 and 34mg/mL;16 although several studies have reported discrepancies between labelled and measured nicotine content.17 , 18 At high enough doses, nicotine has acute toxicity.19 Vaping is unlikely to cause nicotine overdose or intoxication, since the amount consumed and absorbed is quite low and comparable to smoking.20-22 However, some e-liquid cartridges contain nicotine doses that are potentially toxic in adults and children if used in ways other than intended.23 Intentional or accidental exposure to e-liquids can cause adverse health effects such as seizures, anoxic brain injury, vomiting, lactic acidosis, and death.24 In recent years there have been increasing numbers of calls to poison information centres due to unintended ingestion of the e-liquid,25 , 26 particularly by children,27-29 with a baby in the US30 and a toddler in Israel31 reportedly dying after drinking from an e-cigarette refill bottle. The implementation of legislation requiring child-resistant packaging for liquid nicotine containers in the US appears to have reduced exposures to liquid nicotine among young children.32 There have also been limited reports of intentional intoxication by injection and ingestion and a small number of suicide attempts associated with the cartridges.33-35 E-cigarettes may also leak, presenting a hazard as nicotine can be absorbed through the skin.36
18.4.2 Abuse potential
126.96.36.199 Nicotine addiction
Nicotine is among the most addictive of substances known.37 , 38 Although e-cigarette users appear to be less dependent on their product than comparable smokers,39-41 most users still considered themselves to be addicted.40 E-cigarettes may deliver systemic nicotine concentrations in a similar range to,16 , 42 or even in excess of,43 those delivered by combustible cigarettes.
Nicotine absorption and dependency depends on how the e-cigarettes are used; types of puffs and intensity can determine the amounts of nicotine inhaled, in addition to the nicotine concentration of the e-liquid.44 Some policy makers have suggested reducing the nicotine concentration in e-liquid to reduce the addictive potential of the products. For example, in the EU, nicotine content is limited to 20mg/ml. However, research suggests that among experienced vapers, such reductions do not translate to a reduction in nicotine absorption, possibly due to compensatory puffing.45 , 46
Nicotine addiction is discussed further in Chapter 6 - Addiction.
188.8.131.52 Vaping of other drugs
Along with nicotine, there are concerns that e-cigarettes are being used to consume cannabis, particularly among young people.47 , 48 Estimates of ever using an e-cigarette to use cannabis products in youth and young adult samples across North America range from 8 percent to 29 percent.24 Cannabinoid-enriched e-liquids are available for purchase online, or users can also reportedly download recipes and attempt to make their own cannabis e-liquid.49 With the increasing legalisation of cannabis, the e-cigarette and cannabis industries and customer bases are likely to become increasingly intertwined.24
A review of the health effects of cannabis-vaping reached similar conclusions to the general literature: cannabis-vaping is likely less harmful than smoking traditional joints; cannabis e-liquids are unregulated and lack any toxicological and clinical assessment; both cannabis and nicotine pose risks to the neurodevelopment of young people, and also increase their risk of addiction; data on the potential health consequences of vaping cannabis for users and bystanders is extremely limited, and further research is urgently needed.49 Some have suggested that e-cigarettes show promise for the safe and efficient administration of medicinal cannabis.50
E-cigarettes can also be used to vape other types of drugs.49 A review of e-cigarettes as an illicit drug delivery system found evidence of current use of e-cigarettes to vape almost all illicit drug types analysed. The authors highlighted that such use (via an easy to administer route and tool) may lead to higher levels and unusual patterns of drug use (continuous versus acute administration), potential increases in young adult use, addiction and toxicity, and paediatric accidental exposure.51 Data on the prevalence of this type of use is limited, although an online survey of UK adults found that of the respondents that had used an electronic vaping device, more than one-third (39.5%) had ever used them to vape recreational drugs, and more than one-quarter (27.4%) reported current use. The most common drug vaped was cannabis (lifetime use 65.7%). Lifetime use was also high for vaping MDMA/’ecstasy’ (42.8%), cocaine powder (39.8%), mephedrone (30.9%), crack cocaine (30.5%), synthetic cannabinoid receptor agonists (28.4%), fentanyl (26.7%), heroin (25.8%), alpha-PVP (alpha-pyrrolidinopentiophenone)(25.8%), typtamines (25.4%), NBOMe (2, 5-dimethoxy-4-bromophenethylamine) (25%) and ketamine (24.6%).52
E-cigarettes typically deliver e-liquid to the heating coil via saturated wicking material; however, “dripping” involves users putting a few drops of e-liquid directly onto an atomiser’s coil and then immediately inhaling the vapour that is produced.53 Limited evidence suggests that dripping can expose users to high temperatures and toxic chemicals such as aldehydes.54
One study in Colorado found that among high school students who had ever used e-cigarettes, about one quarter (26.1%) had used the product for dripping.53 However, the study was criticised for inadequately defining and measuring the concept.55 Further research is needed regarding the use and health effects of dripping, both for consumer information and to inform regulations.56
18.4.3 Environmental impact
Last updated: February 2023
Cigarette manufacturing has a substantial environmental impact (see Section 10.15), and cigarette butt litter remains a major environmental pollutant that poisons waterways and wildlife and causes bushfires (see Section 10.16). There is also a growing awareness57-63 that “[f]rom mining to manufacturing, the e-cigarette product lifecycle presents novel environmental harms compared with traditional cigarettes.”64
E-cigarettes can be broadly categorised into three types:
- the open or refillable system which includes box mods, pens and refillable pods;
- closed pod systems which use disposable pods;
- single-use products which have a built-in e-liquid cartridge that cannot be replaced or refilled.
Many models, brands and flavours exist within each category.65
There are, however, common aspects of e-cigarettes varieties. Their construction involves “new classes of plastics, metals, cartridges, lithium-ion batteries, concentrated nicotine solutions” and sophisticated but low-cost electronics that are used in “significantly more environmentally intensive manufacturing processes than products that are primarily made of plant material and plastic filters, as combustible cigarettes.”58
Inconsistent and selective US regulation has skewed the e-cigarette market. In January 2020 the FDA announced regulations prohibiting the sale of flavoured (with the exception of menthol and cigarette flavours) closed pod system e-cigarettes, such as market leader Juul. This measure also exempted all flavours of e-liquids used to refill open-system e-cigarette and the relatively new single-use e-cigarette sector led by Puff Bar. This has led to a predictable impact on sales. Single-use e-cigarettes went from 10.3% of total sales in August 2019 10 19.8% by May 2020, and increased by 1000% among high school students in the US.66 Between February 2020 and March 2021 total monthly sales in the US increased by 46.3% to 21.7 million e-cigarettes and sales of prefilled cartridges (pods) increased by 15.2%, from 12.0 million to 13.8 million. In the same period, sales of single-use e-cigarettes went from 2.8 million to 7.8 million, an increase of 181.6%, and a growth in overall market share from 18.8% to 36.1%.67
The continuing strength of Juul and the shift to single-use e-cigarettes68 has significant implications for the environmental impacts of e-cigarette waste. The Juul stick, its main component, can be used repeatedly but the plastic-e-liquid pods it requires are single-use. Single-use e-cigarettes contain e-waste components similar to open- and closed-system e-cigarettes, however, they can be used for a limited time (about 400 puffs or 20–40 cigarettes' worth of aerosol) before being used up and repurchased, creating greater net waste.64
E-cigarette waste should be considered electronic-waste64 and, as such, should not be disposed of in regular rubbish bins. The lithium-ion batteries found in e-cigarettes contain flammable and combustible liquid electrolytes that can cause fires and explosions if the battery overheats (see Section 184.108.40.206).69 Lithium-ion batteries that are disposed of in household waste and recycling, if damaged, can cause fires in waste management facilities, waste disposal vehicles and landfills.70 Used pods and single-use e-cigarettes also contain often significant levels of residual nicotine, which potentially makes them both e-waste and biohazard waste.63
As is the case with traditional combustible cigarettes, users of e-cigarettes are often uncertain about how to dispose of use components. A 2020 US survey found that 51% of young e-cigarette users disposed of pods or empty single-use e-cigarettes into general rubbish bins, 17% put them into regular recycling bins not designed for e-cigarettes and 10% reported that they threw them onto the ground.61
The e-liquid in e-cigarettes contains nicotine, heavy metals, such as lead and mercury, and other hazardous chemicals that can leach into the soil and waterways when disposed of in landfills or littered.71 The lithium-ion batteries and plastics in single-use e-cigarettes also degrade, leaking further chemicals and microplastics into the environment.72 , 73 E-cigarettes are also not biodegradable.73
The nicotine contained in e-cigarettes can be toxic if ingested or absorbed by the skin, particularly for children and animals (see Section 220.127.116.11). Littered e-cigarettes could expose small children and animals to the risk of poisoning and pose choking hazards. i
18.104.22.168 Public perceptions
A US survey conducted in 2019 found high levels of recognition of the environmental harms presented by e-cigarettes among young people. The majority of respondents recognised that empty e-cigarettes, pods, cartridges and refills are litter (86.9%), the danger of disposing of e-cigarette waste in general rubbish (75.8%), and that e-cigarettes are not biodegradable (65.7%). Most respondents also knew that e-cigarettes and related materials contain substances that are toxic to humans (84.1%) and harmful to animals (89.8%). However, recognition of the danger of disposing e-cigarette waste in general rubbish was less common among respondents who had ever used e-cigarettes compared to never-users (71.0% vs. 81.4%). Respondents also indicated that they wanted an appropriate and convenient method to recycle e-cigarette devices; 75.7% of device owners reported that they had considered recycling e-cigarettes. Though more than half (57.8%) of past month e-cigarette users reported that it was inconvenient to responsibly dispose of e-cigarette waste.74
22.214.171.124 Manufacturers’ response to e-cigarette waste
The manufacturers of e-cigarettes are aware of environmental issues associated with e-cigarette disposal but have to date failed to provide consumers with advice on appropriate disposal, unlike other electronic products, or taken responsibility for waste by-product.58 , 64 , 66 , 74
126.96.36.199 Policy response
Regulation of e-cigarettes has been slow to keep up with their rapid growth in popularity. Proposed regulation in the US has been diluted and delayed since 2010 and the deadline for the US Food and Drug Administration to assess manufacturers’ Premarket Tobacco Applications was pushed back on several occasions. This has left manufacturers to continue to produce e-cigarettes with minimal health or environmental oversight.58 In the UK, e-cigarette disposal and recycling is meant to follow guidelines set out in the Waste Electrical and Electronic Equipment Regulations, which require companies to process waste, but the onus for compliance is placed on consumers who are responsible for the costs and efforts of sending waste by-products back to manufacturers.58
In Australia, the prevalence of e-cigarette use continues to grow (see Section 18.3.1), and concerns about the disposal of e-cigarette components and their environmental impact are part of ongoing discussions of e-cigarette regulation.
Under Australian law, e-cigarettes and e-liquids that contain nicotine can only be sold to people with a valid prescription, and cannot be sold from retail outlets other than pharmacies (see Section 18.13) for further information. The Pharmaceutical Society of Australia (PSA) provides the following advice to pharmacists about how they should advise patients who are dispensed nicotine vaping products from their pharmacies.
Nicotine vaping products and vaping devices are hazardous waste.
Advise patients to return any unused nicotine vaping products (and empty nicotine vaping product containers that may contain residual nicotine) to the pharmacy for appropriate disposal through the return of unwanted medicines (RUM) program. Advise patients to switch vaping devices ‘off’ and remove rechargeable batteries prior to disposing in the household rubbish.
Rechargeable batteries can be disposed of according to local council recommendations.
Contact your local council for information about disposal of household quantities of closed system [single-use] ‘disposable’ vaping devices.
If the waste must be stored prior to disposal, advise patients to store it securely and out of reach of children.”75
Since the publication of the PSA’s guidelines, it was reported that the Battery Stewardship Council has advised that its battery collection points are not able to accept single-use e-cigarettes with an encapsulated battery. If the e-cigarette contains a battery that can be safely removed from the device, the separated battery can be disposed of at a battery collection point.76 Consequently, there is currently no safe way to dispose of single-use e-cigarettes. It seems unlikely that people would take their e-cigarette components to council recycling/waste management centres. In addition, many e-cigarette users in Australia obtain their e-cigarettes from sources other than pharmacies;77 non-nicotine e-cigarettes can be sold to adults aged 18+ in retail stores in most states/territories (see Section 18.13). These products also create considerable litter, e-waste and hazardous chemical waste in Australia.
Clear regulation at all levels of government is needed to establish standards for effective disposal and/or recycling of e-cigarettes and their components. There is also discussion of applying an extended producer responsibility (EPR) approach78 to e-cigarettes, which has also been a suggested response to cigarette butt waste (see Section 10.16.3).74 An EPR approach would make manufacturers responsible for the full life cycle of e-cigarettes and mitigate the “looming environmental threat”58 posed by e-cigarette use and disposal. Effective industry EPR should also remove the economic costs of waste management from governments.79 The implementation an EPR scheme to e-cigarettes or other tobacco products should be carefully considered with regards to government obligations under the World Health Organization’s Framework Convention on Tobacco Control Article 5.3, to protect public health policies from tobacco industry interference.80
i Cigarette manufacturing also has a substantial environmental impact (see section 10.15), and cigarette butt litter remains a major environmental pollutant that poisons waterways and wildlife and causes bushfires (see section 10.16).
Relevant news and research
For recent news items and research on this topic, click here. ( Last updated January 2023)
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2. Jiwani AZ, Williams JF, Rizzo JA, Chung KK, King BT, et al. Thermal injury patterns associated with electronic cigarettes. Int J Burns Trauma, 2017; 7(1):1–5. Available from: http://www.ncbi.nlm.nih.gov/pubmed/28123861
3. Kumetz EA, Hurst ND, Cudnik RJ, and Rudinsky SL. Electronic cigarette explosion injuries: A case series. American Journal of Emergency Medicine, 2016. Available from: http://www.ncbi.nlm.nih.gov/pubmed/27133537
4. Nicoll KJ, Rose AM, Khan MA, Quaba O, and Lowrie AG. Thigh burns from exploding e-cigarette lithium ion batteries: First case series. Burns, 2016. Available from: http://www.ncbi.nlm.nih.gov/pubmed/27118069
5. Ramirez JI, Ridgway CA, Lee JG, Potenza BM, Sen S, et al. The unrecognized epidemic of electronic cigarette burns. Journal of Burn Care & Research, 2017; 38(4):220–4. Available from: http://www.ncbi.nlm.nih.gov/pubmed/28644205
6. Sheckter C, Chattopadhyay A, Paro J, and Karanas Y. Burns resulting from spontaneous combustion of electronic cigarettes: a case series. Burns Trauma, 2016; 4:35. Available from: http://www.ncbi.nlm.nih.gov/pubmed/27995151
7. Treitl D, Solomon R, Davare DL, Sanchez R, and Kiffin C. Full and partial thickness burns from spontaneous combustion of e-cigarette lithium-ion batteries with review of literature. The Journal of Emergency Medicine, 2017. Available from: http://www.ncbi.nlm.nih.gov/pubmed/28501385
8. U.S. Fire Administration. Electronic cigarette fires and explosions. 2014. Available from: https://www.usfa.fema.gov/downloads/pdf/publications/electronic_cigarettes.pdf
9. Rossheim ME, Livingston MD, Soule EK, Zeraye HA, and Thombs DL. Electronic cigarette explosion and burn injuries, US Emergency Departments 2015-2017. Tobacco Control, 2018. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30219795
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13. Man killed as e-cigarette 'explodes', Merseyside fire service says. BBC News, 2014. Available from: http://www.bbc.com/news/uk-england-merseyside-28701515
14. International Civil Aviation Organization. ICAO confirms new e-cigarette restrictions. 2015. Available from: http://www.icao.int/Newsroom/Pages/ICAO-Confirms-New-E-Cigarette-Restrictions.aspx
15. U.S. Fire Administration. Electronic cigarette fires and explosions in the United States 2009 - 2016. Federal Emergency Management Agency, 2017. Available from: https://www.usfa.fema.gov/downloads/pdf/publications/electronic_cigarettes.pdf
16. Schroeder MJ and Hoffman AC. Electronic cigarettes and nicotine clinical pharmacology. Tobacco Control, 2014; 23 (Suppl 2):ii30–5. Available from: http://www.ncbi.nlm.nih.gov/pubmed/24732160
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19. U.S. Department of Health and Human Services. The Health Consequences of Smoking: 50 Years of Progress. A Report of the Surgeon General. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2014. Available from: http://www.surgeongeneral.gov/library/reports/50-years-of-progress/full-report.pdf.
20. Farsalinos KE, Romagna G, Tsiapras D, Kyrzopoulos S, and Voudris V. Evaluation of electronic cigarette use (vaping) topography and estimation of liquid consumption: implications for research protocol standards definition and for public health authorities’ regulation. International Journal of Environmental Research and Public Health, 2013; 10(6):2500–14. Available from: http://www.ncbi.nlm.nih.gov/pubmed/23778060
21. Nides MA, Leischow SJ, Bhatter M, and Simmons M. Nicotine blood levels and short-term smoking reduction with an electronic nicotine delivery system. American Journal of Health Behavior, 2014; 38(2):265–74. Available from: http://www.ncbi.nlm.nih.gov/pubmed/24629555
22. Dawkins L, Kimber C, Panwanesarasa Y, and Soar K. First versus second generation electronic cigarettes: predictors of choice and effects on urge to smoke and withdrawal symptoms. Addiction, 2014. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25407505
23. Cameron JM, Howell DN, White JR, Andrenyak DM, Layton ME, et al. Variable and potentially fatal amounts of nicotine in e-cigarette nicotine solutions. Tobacco Control, 2014; 23(1):77–8. Available from: https://www.ncbi.nlm.nih.gov/pubmed/23407110
24. National Academies of Sciences Engineering and Medicine. Public health consequences of e-cigarettes. The National Academies Press, Washington, DC 2018. Available from: http://nationalacademies.org/hmd/Reports/2018/public-health-consequences-of-e-cigarettes.aspx.
25. Centers for Disease Control and Prevention. Press Release: ‘New CDC study finds dramatic increase in e-cigarette-related calls to poison centers’. 2014. Available from: http://www.cdc.gov/media/releases/2014/p0403-e-cigarette-poison.html
26. Branley A. Health experts alarmed after rise in accidental poisoning from e-cigarettes. ABC News, 2014. Available from: http://www.abc.net.au/news/2014-08-27/accidental-poisoning-from-ecigarettes-on-the-rise/5699592>
27. England LJ, Bunnell RE, Pechacek TF, Tong VT, and McAfee TA. Nicotine and the developing human: a neglected element in the electronic cigarette debate. American Journal of Preventive Medicine, 2015; 49(2):286–93. Available from: https://www.ncbi.nlm.nih.gov/pubmed/25794473
28. Hagen K. E-cigarettes poisoning Victorian Toddlers. The Age, 2014. Available from: http://www.theage.com.au/national/ecigarettes-poisoning-victorian-toddlers-20140606-39ohu.html?skin=text-only
29. Kamboj A, Spiller HA, Casavant MJ, Chounthirath T, and Smith GA. Pediatric exposure to e-cigarettes, nicotine, and tobacco products in the United States. Pediatrics, 2016; 137(6). Available from: http://www.ncbi.nlm.nih.gov/pubmed/27244861
30. Withnall A. First 'e-cigarette child death': New York baby dies after drinking liquid nicotine. The Independent, 2014. Available from: http://www.independent.co.uk/news/world/americas/first-ecigarette-child-death-new-york-baby-dies-after-drinking-liquid-nicotine-9924229.html
31. Winer S. Police investigating toddler’s death from nicotine overdose. The Times of Israel, 2013. Available from: http://www.timesofisrael.com/police-investigating-toddler-death-from-nicotine-overdose/
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33. Cervellin G, Luci M, Bellini C, and Lippi G. Bad news about an old poison. A case of nicotine poisoning due to both ingestion and injection of the content of an electronic cigarette refill. Emergency Care Journal, 2013; 9(2):18. Available from: http://ftp.oncologyreviews.org/index.php/ecj/article/view/ecj.2013.e18
34. Christensen LB, van’t Veen T, and Bang J. Three cases of attempted suicide by ingestion of nicotine liquid used in e-cigarettes. XXXIII International Congress of the European Association of Poisons Centres and Clinical Toxicologists (EAPCCT), 2013. Available from: http://www.e-cigarette-research.info/doku.php/research:documents:f87h87fv
35. Park EJ and Min YG. The emerging method of suicide by electronic cigarette liquid: a case report. Journal of Korean Medical Science, 2018; 33(11):e52. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29495133
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39. Etter JF and Eissenberg T. Dependence levels in users of electronic cigarettes, nicotine gums and tobacco cigarettes. Drug and Alcohol Dependence, 2015; 147:68–75. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25561385
40. Liu G, Wasserman E, Kong L, and Foulds J. A comparison of nicotine dependence among exclusive E-cigarette and cigarette users in the PATH study. Preventive Medicine, 2017; 104:86–91. Available from: https://www.ncbi.nlm.nih.gov/pubmed/28389330
41. Rostron BL, Schroeder MJ, and Ambrose BK. Dependence symptoms and cessation intentions among US adult daily cigarette, cigar, and e-cigarette users, 2012-2013. BMC Public Health, 2016; 16(1):814. Available from: http://www.ncbi.nlm.nih.gov/pubmed/27538489
42. Shahab L, Goniewicz ML, Blount BC, Brown J, McNeill A, et al. Nicotine, carcinogen, and toxin exposure in long-term e-cigarette and nicotine replacement therapy users: a cross-sectional study. Annals of Internal Medicine, 2017. Available from: http://www.ncbi.nlm.nih.gov/pubmed/28166548
43. Ramoa CP, Hiler MM, Spindle TR, Lopez AA, Karaoghlanian N, et al. Electronic cigarette nicotine delivery can exceed that of combustible cigarettes: a preliminary report. Tobacco Control, 2016; 25(e1):e6–9. Available from: http://www.ncbi.nlm.nih.gov/pubmed/26324250
44. Byrne S, Brindal E, Williams G, Anastasiou K, Tonkin A, et al. E-cigarettes, smoking and health. A Literature Review Update. CSIRO, Australia, 2018. Available from: https://researchnow.flinders.edu.au/en/publications/e-cigarettes-smoking-and-health-a-literature-review-update.
45. Soar K, Kimber C, McRobbie H, and Dawkins LE. Nicotine absorption from e-cigarettes over 12 months. Addictive Behaviors, 2018. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30054021
46. Kosmider L, Kimber CF, Kurek J, Corcoran O, and Dawkins LE. Compensatory puffing with lower nicotine concentration e-liquids increases carbonyl exposure in e-cigarette aerosols. Nicotine & Tobacco Research, 2018; 20(8):998–1003. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29065196
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48. Cassidy RN, Meisel MK, DiGuiseppi G, Balestrieri S, and Barnett NP. Initiation of vaporizing cannabis: Individual and social network predictors in a longitudinal study of young adults. Drug and Alcohol Dependence, 2018; 188:334–40. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29857317
49. Giroud C, de Cesare M, Berthet A, Varlet V, Concha-Lozano N, et al. E-cigarettes: a review of new trends in cannabis use. International Journal of Environmental Research and Public Health, 2015; 12(8):9988–10008. Available from: http://www.ncbi.nlm.nih.gov/pubmed/26308021
50. Lanz C, Mattsson J, Soydaner U, and Brenneisen R. Medicinal cannabis: in vitro validation of vaporizers for the smoke-free inhalation of cannabis. PLoS One, 2016; 11(1):e0147286. Available from: http://www.ncbi.nlm.nih.gov/pubmed/26784441
51. Breitbarth AK, Morgan J, and Jones AL. E-cigarettes-An unintended illicit drug delivery system. Drug and Alcohol Dependence, 2018; 192:98-111. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30245461
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