E-cigarettes an evidence update A report commissioned by Public Health England

E-cigarettes: an evidence updatepoorly labelled products are now less common and overall the labelling accuracy hasimproved. For instance in the latest study which sampled 263 liquids from 13manufacturers, the correlation between the declared and measured concentrations wasr=0.94 with the samples ranging from -17% to +6% of the declared value [85]. Inanother study testing the five most popular EC brands, the consistency of nicotinecontent across different batches of nicotine cartridges of the same products was foundto be within the accuracy required from medicinal nebulisers [100]. Given the generallyadequate labelling accuracy and the fact that the actual nicotine intake by vapers isdictated by a host of other factors discussed below, the accuracy of labelling of commone-liquids poses no major concerns.Is there is a risk from e-liquids inaccurately labelled as containing 0 nicotine?All samples labelled as containing 0 nicotine were nicotine free in the newer studies, butthree early studies found nicotine in some samples of ‘0 nicotine’ e-liquids. One samplereported in 2011 was clearly mislabelled [87] but in all other cases, only tracecontamination was detected (below 1mg/ml). This would have no central effect onusers.SummaryPoorly labelled e-liquid and e-cartridges mostly contained less nicotine than declaredand so posed no risk to users. The accuracy of product labelling currently raises nomajor concerns.Nicotine in e-vapourA number of studies evaluated nicotine in EC vapour generated by puffing machines. Arecent experiment [101] has shown that parameters of puffing topography, especiallypuff duration and puff frequency, have a major influence on nicotine delivery. This posesa serious problem in interpreting the existing studies. The key parameters used bypuffing machines differ widely across studies, and may not correspond well or at all withvapers’ behaviour generally and especially with the way individual EC products areused. To illustrate the point, Table 7 below, from Cheng et al. 2014 [84], shows the widerange of settings used in different studies. (Table 7 includes some unpublished studies).Table 7. Settings of EC puffing parameters. From Cheng et al 2014 [84].StudyPuff volume(mL)Puff interval(s)Puff duration(s)Puffs/sessionSmokingmachineGoniewicz et al [100] 70 10 1.8 15 Palaczbot*Pellegrino et al [89] 498 8 3 16 Aspiration68