Background:
Wastewater analysis is a method of routinely sampling the wastewater within a city to detect drug metabolites. Smoking by-products such as nicotine enter the sewerage network via urine excretion of people consuming cigarettes. Concentrations of nicotine and cotinine are calculated at sewerage treatment plants and converted to population consumption estimates. A similar approach has been routinely used to estimate illicit drug use for some time. This presentation will outline the pros and cons of wastewater analysis for population nicotine consumption estimates.

Methods:
Nicotine (cotinine) sampling occurred every two months from four wastewater treatment plants across the city of Adelaide, South Australia. Simultaneously, a South Australian telephone monitoring survey (n=600 per month) was used to calculate bi-monthly tobacco cigarette consumption among metropolitan residents. Data collection occurred from December 2011 and will include data until December 2017. The trends of both data sets will be compared.

Results:
The wastewater and population survey data trends corresponded reasonably well until early 2015. Since then the trends have diverged, with the wastewater trend showing a small but steady decline in nicotine consumption whereas the population survey data trend shows large fluctuations in cigarette consumption. Potential reasons for the divergence include: wastewater analysis not distinguishing the source of nicotine (e.g. tobacco cigarettes, NRT, or e-cigarettes) and large confidence intervals for monthly population survey monitoring.

Conclusions:
Nicotine and its metabolite cotinine are non-specific for tobacco smoking. Therefore, wastewater analysis for tobacco smoking may supplement population monitoring of nicotine consumption but is not sufficient for detecting changes in quitting activity and smoking prevalence. Further research is needed to determine whether other tobacco-specific metabolites can be monitored to address these limitations. One advantage of wastewater analysis is that it provides an objective measure that can be compared across jurisdictions.