This latest study, carried out by Soa, Kimber, McRobbie and Dawkins is titled “Nicotine absorption from e-cigarettes over 12 months” and published in the Addictive Behaviors journal.
In the paper, the team write: “although vapers may perceive a reduction in nicotine concentration e-liquid as a move to reducing nicotine intake, this may not necessarily be the case. For example, reported that over an 8-month period, although exclusive vapers decreased the concentration of nicotine in their e-liquid, the amount of liquid consumed increased and salivary cotinine (a metabolite of nicotine) levels remained stable.”
Vapers were self-titrating nicotine by increasing the volume of juice used to cope with the lower levels of nicotine in the liquid.
It follows on from a paper published by King, Ndoen and Borland, who wrote the large-scale ignorance surrounding vaping and the difference between using nicotine and smoking. The confusion isn’t surprising given that a Google image search for nicotine links to a wealth of cigarette images – such misunderstandings are reinforced throughout the media.
The team from Queens, East London and South Bank recruited 32 vapers, most having vaped for around three years, and followed them for twelve months. Three returned to smoking leaving 29 subjects; of those, a third subohmed from time to time and a quarter subohmed daily. Two-thirds used a 50/50 liquid.
“There was an increase in the number of reports of sub-ohming and use of fruit flavoured e-liquids after 12 months relative to baseline.”
One person dropped out of the study and one failed to respond during the follow up after a year had passed. The cohort was surveyed again and the team discovered: “self-reported nicotine concentrations in e-liquid declined significantly over time whilst volume of e-liquid consumed significantly increased.”
“It therefore appears that whilst vapers reduce the nicotine concentration of their e-liquid, this has no effect on their nicotine intake since levels of nicotine absorption remain stable. This could possibly occur through a self-titration mechanism (e.g. increasing the volume of liquid consumed by altering puffing patterns in response to a change in nicotine exposure). These findings are in line with our previous work on compensatory puffing; in 11 experienced vapers tested in the lab, liquid consumption and puff number were higher, and puff duration longer, when using a low (6 mg/ mL) compared with a high (24 mg/mL) nicotine concentration e-liquid (Dawkins et al., 2016).”
Dr Konstantinos Farsalinos has previously spoken about such behaviour: “What I think vapers need to understand is that the amount of exposure depends on how much liquid you consume. The problem I see with subohming is that usually, when vapers transition from mouth-to-lung vaping to direct lung inhalation, they increase their liquid consumption by quite a lot. The more you consume, the more exposure to any potentially toxic chemical. If you double your consumption, you are doubling your exposure to toxins.”
Before anybody panics, he also stated: “I think that today’s products release such low levels of aldehydes that you are probably exposed to more aldehydes by just staying at home and breathing the air in the house than from using an e-cigarette.”