Mouth level exposure (MLE) assessments are valuable in helping interpret, as well as potentially predict, the results from clinical investigations, such as biomarkers of exposure studies. To date, methods to estimate nicotine-MLE from electronic cigarette (e-cig) have not been established.

Previously, we have shown a positive correlation between the nicotine yield from a tobacco vapour product and the weight loss (WL) from its device and its cartridge. In this study, we investigated whether WL can also be used to estimate the nicotine-MLE from e-cigs.

We investigated the correlations between nicotine yield and WL in two types of e-cigs, closed tank type and cig-a-like type, vaped under several regimes by machine vaping. To assess the influence of the puff profile on the correlations under several vaping regimes, two puff profiles were compared: square and bell-shaped. For both types of e-cigs, positive correlations were observed between nicotine yield and WL (closed tank; R²>0.97, cig-a-like; R²>0.93). When tested at the same liquid nicotine concentration (2.4 % w/w), the correlation between vapor nicotine yield and WL was similar between the two types of e-cigs (closed tank; nicotine (mg) = -0.028 + 17.819*WL (g), cig-a-like; nicotine = -0.125 + 18.151*WL). These results indicate that the liquid nicotine concentration, rather than device, is a primary determinant of the vapor nicotine yield. In this study, the nicotine yields and WLs measured under bell puff profiles lay within the 95 % confidence intervals for regression lines obtained with square puff profiles. This result suggests that puff profiles have a limited influence on the correlations between nicotine yields and WLs. In conclusion, the results from this study support the hypothesis that WL can be used to estimate nicotine-MLE from different types of e-cigs, irrespective of puff profile.