JUUL releases more nicotine in the first puffs

Abstract

Analytical studies that estimate nicotine and other toxicant emissions from electronic cigarettes (ecigarettes) typically employ a puffing machine to generate 10 or 15 puffs in rapid succession (eg, 30 s between puffs) for subsequent assays. 2 Such puffing patterns model combustible cigarette use in which every hour or so a smoker takes a 5 min break to consume a cigarette, a use duration intrinsic to the burning rate and length of the cigarette rod. A single cigarette is the default ‘serving size’ to which the consumer commits once the cigarette has been lit. On the contrary, ecigarettes such as JUUL have no intrinsic serving size; the design is agnostic to a user drawing a single puff or tens of puffs in a use bout. Indeed, emerging evidence suggests that JUUL use patterns are characterised by sporadic puffing throughout the day, for example, at the work desk, during exercise and during class. 4 A recent study found that nearly half of exclusive JUUL users report typically drawing four or fewer puffs from their device during a use bout. We examined whether using JUUL in such a manner might result in different nicotine emissions per puff than predicted by a standardised 10puff regimen. We measured puffbypuff liquid consumption for two JUUL products obtained in the UK in 2019: Golden Tobacco (20 mg/mL label) and ‘New Technology’ Golden Tobacco (18 mg/ mL label) JUUL pods. Three brandnew pods of each product were used to each generate three puffing bouts consisting of ten 4 s puffs with a 1 L/min flow rate and 30 s interpuff interval, within the range of recently reported JUUL topography parameters. Each bout was separated by 30 min. We fully recharged the same battery prior to every session to power each JUUL pod. The amount of aerosol emitted per puff was determined gravimetrically by weighing the JUUL device after each puff, during the interpuff interval. Nicotine yield per puff was estimated as the product of the liquid consumed per puff and the previously measured liquid nicotine concentration of 19 mg/mL for both products. Puffbypuff computed nicotine emissions are presented in figure 1. We found that for both product types, the computed nicotine yield was greatest during the first puffs and systematically decreased until steadying at the fifth puff. The same trend was observed in every test session, including repeats with the same pods (ie, after the 30 min rest period). These results suggest that previous reports of JUUL nicotine yields that are based on the emissions collected from a succession of 10–15 puffs underestimate the true perpuff nicotine intake of a JUUL user because they average the emissions from all 15 puffs. One limitation is that we only tested one topography regimen; others may yield different results but are unlikely to affect the general conclusion of this study that the first JUUL puffs result in higher emissions, as routinely reported in online user forums. The tobacco industry has long recognised the importance to dependence formation of the first puffs of a cigarette ‘which are more likely to be noticed and assessed by a smoker’ and has manipulated cigarette chemistry accordingly. It is not clear whether JUUL’s higher emissions in the first few puffs are intentional design features or how this may affect its abuse liability profile. These questions are worth investigating.