Understanding nicotine consumption habits in Aotearoa New Zealand using wastewater-based epidemiology

In 2022, the rate of daily smokers in Aotearoa New Zealand fell to 8 %, a historical low that reflected the efficacy of efforts and regulation to meet the NZ government's Smokefree 2025 goal. However, the use of e-cigarettes/vaping has rapidly increased over the past several years, overtaking cigarette use in 2021. This study employed wastewater-based epidemiology (WBE) to monitor and understand NZ nicotine consumption, with the aim of analysing both smoking and vaping habits in NZ. To this end, this research involved the development, validation and implementation of an SPE-LC-MS/MS method to analyse nicotine metabolites and tobacco-specific minor alkaloids in wastewater. A total of 142 wastewater samples from 12 different wastewater treatment plants (WWTPs) from nine settlements across NZ, collected twice a week for one week per month, from May to October 2023, were analysed. The population-weighted average nicotine consumption across all samples was 2467 mg/day/1000 people with no significant difference between weekday and weekend consumption, except for one site. The relative ratio of smoking-specific analytes and the total nicotine metabolites was analysed in order to obtain the relative proportion of nicotine obtained from tobacco vs vaping and other sources, with significant differences seen in both the total nicotine and mode of its consumption in different locations in Aotearoa New Zealand. This is the first study to investigate different modes of nicotine consumption in a NZ population using WBE, providing reliable and current data that will be useful information to the NZ government and health organisations.