“…However, for compounds that show significantly less extraction than nicotine such as metals (Cuello-Nuñez et al 2018), these estimations should be viewed as conservative. Using reported nicotine extraction of 44-72% for gum NRT (Benowitz et al 1987, Lunell and Lunell 2005a, Lunell and Curvall 2011, Digard et al 2013a, Hansson et al 2019, 30-39% for snus (Lunell and Lunell 2005a, Caraway and Chen 2013, Digard et al 2013a, b, Lunell et al 2020, and 56% and 59% for NPs (Lunell et al 2020), we calculated average f EU values of 0.62, 0.33 and 0.58 for gum, snus and NPs, respectively; in addition, we assumed f EU ¼ 1 for the lozenge NRT, which dissolves completely in the user's mouth. These f EU values were assigned to the extraction of all toxicants except for metals from snus, which have been established as having extraction efficiencies of 10% or less (Lunell andLunell 2005b, Caraway andChen 2013); we therefore used f EU ¼ 0.1 for cadmium, nickel and mercury, and conservative estimates of f EU ¼ 0.05 for arsenic, chromium and lead (Supplementary Table 2).…”