What’s in a vape?

Exploring the chemical, physiological and psychological effects of e-cigarettes

Vapes were promoted as a way to quit smoking, but now the trend is in a league of its own.

Tobacco smoking in Australia has been in consistent decline, with numbers dropping by more than half since 1995. However, while smoking rates drop, the number of people vaping continues to rise.  

According to the latest census data, almost one in ten Australians between 18-24 have tried a vape, and research from the Alcohol and Drug Foundation shows more than 14% of adolescents aged 12-17 have vaped at least once.  

Dr Celine Kelso is a researcher in the School of Chemistry and Molecular Biosciences at the University of Wollongong (UOW). She has been investigating the chemical contents of e-cigarettes and is in the process of setting up vapour studies to determine the harms of some of these chemicals to airways using in vitro cell studies.   

“Around 90 per cent of the e-liquid in vapes is made up of propylene glycol and vegetable glycerine, these are called carried fluids. E-liquids contained in vapes are made from these two chemicals and come in different ratios.” she says.  

“Propylene glycol enriches flavours and gives body to e-liquid, and a higher percentage will cause a more noticeable throat hit during the vaping. While vegetable glycerine is more viscous and sweeter and is responsible for the generation of the vapour cloud, so a higher percentage of vegetable glycerine will produce larger clouds.” 

Dr Kelso says most of the flavours contained in vapes are food grade flavouring approved for ingestion, however very few of them have been tested to determine their toxicities via inhalation. In addition to flavouring agents, e-liquids contained in vapes contain cooling agents which help counteract the nicotine burn.  

“The food grade flavouring molecules can be easily found in everyday foods like cakes, lollies, desserts, as well as scented products like candles and air fresheners. Coolants can be used in foods and beverages, but are also found in tobacco products, toiletries, cosmetics, or pharmaceuticals.” she says. 

Dr Kelso says unregulated importation of vapes, and lack of labelling, means users are unaware of the dosage of nicotine they are consuming. 

“Nicotine is classified as a category 2 oral toxicant, with an estimated lethal dose by ingestion of 6.5-13 mg/kg. This estimation would equate to the ingestion of 0.5-1 gram for an average adult weighing 70 to 85 kilograms,” she explains.  

“Although disposable vapes do not have a listed nicotine concentration, our study of over 100 donated samples has found that all e-liquid solutions within these disposable vapes contained, on average, four to five per cent nicotine. We are yet to analyse a disposable device that did not contain any nicotine.” 

Vaping compared to cigarettes 

Vaping was originally sold as an alternative to help smokers ditch cigarettes but has quickly evolved into its own trend. Dr Theresa Larkin from the UOW Graduate School of Medicine says that while vaping is preferable to traditional cigarette smoking, there are always health risks.  

“Vaping works as a substitute for smoking cigarettes because it addresses the physical component of smoking addiction, by providing nicotine, but also addresses the behavioural aspects of a “time-out”, the action of smoking, the presence of the smoke, and the sensory stimulation of inhaling,” she says.  

“For smokers who want to reduce smoking but are addicted, vaping is an effective long-term substitute and is better for their health if they would otherwise smoke a conventional cigarette.” 

“However, the issue is when young adults who otherwise do not smoke, start to vape. In this case, it is not a better substitute of something more damaging to health, it is a new behaviour, inhalation of an addictive substance (nicotine) and potentially damaging to otherwise healthy airways, lungs, heart, blood vessels and the brain.” 

Because of its novelty, there is little evidence to show the long-term effects of using e-cigarettes. 

“We won’t know about the long-term effects of vaping on lung function for many years. Similarly, we didn’t know about the negative health effects of cigarette smoking for decades,” says Dr Larkin.  

“What is new with vaping, and not known, are the effects of the flavours in e-cigarettes. Most of the flavours are already used in foods, and considered safe in general, but they may have different effects when heated and inhaled. Some of these have been found to negatively affect heart function and heart rate.”  

Fighting addiction with addiction 

Dr Larkin explains that the nicotine in e-cigarettes has the same addictive properties as smoking cigarettes, through the release of dopamine.  

This is echoed by UOW clinical psychologist and addiction expert Dr Sue Thomas, also from the Graduate School of Medicine. 

“When nicotine is inhaled via the airways, it enters the bloodstream through the lungs. From there it easily crosses the blood-brain-barrier and enters the brain. This results in the release of a wide array of neurotransmitters that result in several psychoactive effects, including stimulation, reward, and relaxation,” says Dr Thomas. 

“Of these neurotransmitter effects, the most important is dopamine release, which activates the brain’s dopamine reward pathway. This pathway usually reinforces survival behaviours like eating and sex. All drugs of addiction can hijack this pathway, sending a false signal to the brain that they are good for the person and essential to survival.” 

Dr Thomas says young people are particularly vulnerable to addiction due to the limited formation of their brain’s frontal lobe. This vulnerability has been successfully targeted by the vaping industry, through the pairing of nicotine, appealing flavours, and attractive, discreet devices. 

“E-cigarettes have been promoted on social media through association with attractive, influential people who are popular with young people, along with lifestyle or health claims. Once nicotine becomes “paired” with appealing flavours, places or items, this helps to reinforce the vaping through classical conditioning, a type of learning through association,” she explains.  

“Just as Pavlov’s dogs learned to salivate when the food bell went, young people may crave an e-cigarette when they hear the recess bell if they have been vaping in the school toilets. In the old days the cigarette manufacturers used attractive packaging and advertising to reinforce their sales of cigarettes. The pretty pictures would trigger an association and a craving for their favourite brand. Once the physical addiction has taken hold, it is very difficult to break as it will be repeatedly triggered by the sights, smells, people and places associated with the drug.” 

So, without long-term data available currently, what sort of research will help us understand the effects of vaping?  

Dr Larkin explains, “We will only know the long-term effects in years to come. In the meantime, we can have observational studies of how those who vape (especially teens and young adults) behave, learn, interact, and socialise. What are their levels of wellbeing, how do they do at school? A big part is behavioural, because of the addictive role of nicotine and its effects on other brain functions,” she explains.  

Chemical studies, such as here at UOW are also necessary.  These can help to characterize the components of e-cigarettes, including the flavours and what happens when these are heated.  We can then predict what effects these might have on the human body based on our knowledge of these in other contexts. As data is collected from those who do vape, we can build a picture of what it does to our airways, lungs, heart, brains.  But we already know the negative effects of nicotine on addiction, and the susceptibility to other, future addictions.”