JUUL RELEASES MORE NICOTINE IN THE FIRST PUFFS

Analytical studies that estimate nicotine and other toxicant emissions from electronic cigarettes (e-cigarettes) typically employ a puffing machine to generate 10 or 15 puffs in rapid succession (e.g., 30s between puffs) for subsequent assays.[1, 2] Such puffing patterns model combustible cigarette use in which every hour or so a smoker takes a 5-minute 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 other hand, e-cigarettes 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 characterized by sporadic puffing throughout the day, e.g., at the work desk, during exercise, and during class.[3, 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 [5]. We examined whether using JUUL in such a manner might result in different nicotine emissions per puff than predicted by a standardized 10-puff regimen.

We measured puff-by-puff liquid consumption for two JUUL products obtained in the UK in 2019: Golden Tobacco (20mg/ml label) and “New Technology” Golden Tobacco (18mg/mL label) JUUL pods. Three brand-new pods of each product were used to each generate three puffing bouts consisting of ten 4-sec puffs with a 1L/min flow rate and 30s inter-puff interval, within the range of recently reported JUUL topography parameters.[6] Each bout was separated by 30 minutes. 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 inter-puff interval. Nicotine yield per puff was estimated as the product of the liquid consumed per puff and the previously measured liquid nicotine concentration of 19mg/mL for both products.[7] Puff-by-puff computed nicotine emissions are presented in Figure 1.

Figure 1.

Computed nicotine yield by puff from JUUL and JUUL new technology pods. Each data point represents the average (standard deviation) obtained from three JUUL pods used during three different bouts (N=9 for each data point). Filled symbols indicate a significant difference from the first puff. Additionally, a general linear model analysis showed that puff number is significantly associated with the computed nicotine yield per puff.

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 (i.e., after the 30min 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 [8–10] underestimate the true per-puff 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 result 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 recognized 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.[11] 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.