To facilitate the development of a transfer model which can be used to estimate human exposure to flavour and tobacco constituents, a human in vivo study involving 198 Swedish active snus users was conducted. All subjects agreed to participate in the study. Two snus products (X and Y) manufactured by Skruf Snus AB were selected for the study which were indistinguishable apart from the flavour application rate (%). Participants were divided into two groups (X: n = 98, Y: n = 100) and required to consume three individual pouches for 30 minutes per pouch.

An in-house extraction method^[1] was developed to extract relevant flavour and tobacco constituents from test pouches: Menthol, 1,8-cineole (Eucalyptol) and Nicotine were quantified from dichloromethane/methanol extracts prepared from used and unused pouches. Analysis of Product X test pouches based on the total amount extracted from used snus pouches revealed an average mouth-level transfer rate for menthol, 1,8 cineole and nicotine at 9 (SD ± 14), 25 (SD ± 13) and 22% (SD ± 15), respectively. Analysis of Product Y test pouches demonstrated an average mouth level transfer rate of 13 (SD ± 5), 25 (SD ± 8) and 23% (SD ± 10) for menthol, 1,8-cineole and nicotine, respectively. Intra-human variability for mouth-level exposure of the three replicate pouches was consistent: respectively 98%, 87%, and 89% of the users exhibit an analytical variability below 20% in menthol, 1,8 cineole and nicotine respectively for Product X (99%, 88% and 93% for Product Y). The mouth-level transfer of menthol and 1,8-cineole was positively correlated to their respective water solubilities of 490 mg/L and 3500 mg/L; however an upper transfer limit may be reached due to limited access to saliva. It was concluded that whilst water solubility may be an important factor in the mouth-level transfer of flavour constituents evaluated, the initial flavour application rate is not.

To complete the transfer model, results with an alternative in vitro extraction media (artificial saliva, water and 1% ß-cyclodextrin in water) will be presented.

[1] Analytical method to model human mouth-level transfer. Poster session - CORESTA 2013.