Abstract:
In 2022, the rate of daily smokers in New Zealand (NZ) fell to 8%, a historical low that reflects
the efficacy of efforts and regulation to meet the NZ government’s Smokefree 2025 goal.
Recently, however, the prevalence of e-cigarette/vaping has been shown to rapidly increase -
according to a recent Ministry of Health survey, e-cigarette use rapidly began increasing in
2019 and overtook cigarette use in 2021. Worryingly, e-cigarette usage is high in NZ youths.
To monitor and understand these trends, it is critical to develop reliable procedures to measure
cigarette smoking and vaping prevalence and use this to obtain reliable and current data in NZ.
This study constitutes the most extensive study ever undertaken to understand NZ
nicotine consumption through Wastewater-Based Epidemiology (WBE), with the main aims
of analysing both cigarette smoking and vaping habits in NZ and using this to identify cigarette
smoking & vaping/e-cigarette use trends. To this end, this study involved the development,
validation and implementation of an SPE-LC-MS/MS method to analyse nicotine metabolites
cotinine (COT) and trans-3’-hydroxycotinine (COT-OH) in addition to tobacco-specific minor
alkaloids anatabine (ANTA) and anabasine (ANBA) in wastewater.
In total, 142 wastewater samples were analysed from 12 different wastewater treatment
plants (WWTPs) from nine settlements across NZ, twice a week for one week per month, from
May to October 2023.The average daily mass load of target analytes and the average nicotine
consumption in NZ were higher than expected given NZs reported low smoking prevalence.
While this could potentially be explained by the choice of WWTPs included in this study, this
could also indicate relatively high levels of vaping compared to global usage. The ratio of
tobacco-specific analytes to nicotine metabolites indicated a higher proportion of nicotine is
consumed through vaping in NZ compared to overseas. It was found that different settlements
had vastly different nicotine consumption levels and relative cigarette smoking/vaping habits.
WWTPs with the highest daily mass loads of target analytes (Gisborne, Westport, Auckland
South) generally aligned with smoking prevalence data. Differences between WWTPs were
observed regarding relative cigarette smoking and vaping levels. Additionally, it was found
that there no statistically significant differences in rates of cigarette smoking/vaping in the
weekend compared to weekdays for most WWTPs.
This study is the first to investigate both cigarette smoking and vaping in a NZ
population using WBE, providing reliable and current data on smoking and vaping levels that
will be useful information to the NZ government and health organisations, particularly in the
current pivotal time in NZ regarding Smokefree Aotearoa 2025 and recent legislation changes.