Synthetic Cooling Agents in Australian-Marketed E-cigarette Refill Liquids and Disposable E-cigarettes: Trends Follow the U.S. Market

Abstract

Introduction E-cigarettes are becoming increasingly popular in Australia, especially amongst the younger population. The synthetic cooling molecules WS-3 and WS-23 have been identified in e-cigarette products from the US and Europe. The extent of inclusion of these synthetic coolants in Australian e-liquids is unknown, particularly in newer disposable e-cigarettes. Methods E-cigarettes and e-liquids were purchased within Australia and anonymously donated by Australian users. Nicotine, WS-3, WS-23 and menthol were quantified in the eliquids using gas chromatography – mass spectrometry (GCMS). Results WS-23 and nicotine were detected in all of the disposable e-cigarettes with WS-23 often present in high concentrations. There was no correlation between cooling terms in the flavour name and the inclusion of cooling agents. Only three bottled e-liquids were found to contain WS-23 while none contained WS-3 above the limit of detection. Conclusions Synthetic coolants were a common addition in disposable e-cigarettes while rarely added to e-liquid bottle refills. Their inclusion in these products is reflective of trends observed in US and European ecigarette products.

Chemical Analysis and Flavour Distribution of Electronic Cigarettes in Australian Schools

“…Whilst the sample size for refillable e-liquid analysis was small, these results are consistent with previous research comparing Australian refillable e-liquids and disposable e-liquids. 8 Reports that disposable e-cigarettes will be banned under future legislation in Australia 25 may have a significant effect on youth vaping as the vast majority of students currently use disposable devices.…”

“…WS-23 may be added to disposable e-cigarettes to further reduce the throat irritation associated with high nicotine concentrations and intense flavours among naïve users. 8 A recent survey suggested that more than half of adolescents who reported e-cigarette ever-use had never previously smoked and would therefore be unaware and unaccustomed to the throat irritation. 6 The high concentrations of WS-23 observed throughout this study are noteworthy as previous research has found comparable concentrations to be unsafe based on in vitro studies and may adversely impact the inhalational safety of these products.…”

“…This is possibly due to preferential vaporisation of these compounds resulting in low concentrations or their absence at the end of the device life. 8 However, this does not necessarily account for the large differences in nicotine and WS-23 concentrations in many of the identical devices.…”

“…The e-liquid generally contains the carrier fluids propylene glycol (PG) and vegetable glycerine (VG), nicotine, flavouring chemicals and occasionally synthetic cooling agents (referred to as coolants). [8][9][10] There is little published data on the inhalational safety of the flavouring chemicals and synthetic coolants and the long term effects of e-cigarette usage is relatively unknown. Reactions between some flavouring chemicals and the carrier fluids have been observed to form acetals in situ in e-liquids, the toxicological properties of which are similarly understudied.…”

“…Along with device trends, nicotine strength has increased in the US for disposable e-cigarettes compared to refillable e-liquids since 2017, 19 with recent research showing a similar trend for disposable devices on the Australian market. 8 Several recent surveys of Australian adolescents have provided insights into the current landscape of e-cigarettes amongst this population. [4][5][6]20 Disposable e-cigarette devices are reportedly the most popular type of e-cigarette product obtained with fruity flavours being preferred.…”