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. 2022 Oct 28;31(Suppl 3):s238–s244. doi: 10.1136/tc-2022-057484

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© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

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Heat map showing individual flavour chemicals in refill fluids purchased in 2015, 2016 and 2019. The y-axis shows flavour chemicals ordered by high versus low concentrations, and the x-axis represents product codes as described in online supplemental table S1. Most flavour chemicals were present in low concentrations. However, increases in the concentrations of several commonly used flavour chemicals are seen in products purchased in 2016 and 2019. 2-H-3,5,5-t-c-2-en, 2-Hydroxy-3,5,5-trimethyl-cyclohex-2-en; TMP, trimethylpyrazine.