Monitoring caffeine and nicotine use in a nationwide study in Italy using wastewater-based epidemiology

Smoking cigarettes and drinking coffee are common habits in today's society. However, it is not easy to get up-to-date information on smoking prevalence and caffeine consumption as it is usually obtained from population surveys. To overcome this limitation and complement epidemiological information, we employed wastewater-based epidemiology (WBE) to gain a picture of the consumption of cigarettes and caffeine per day per person in Italy. A nationwide study was conducted by measuring two urinary metabolites of nicotine (cotinine and trans-3'-hydroxycotinine) and a caffeine metabolite (1,7-dimethyluric acid) in untreated wastewater from 16 cities. The spatial profiles of use depended mostly on the specific population habits in each city, not on the geographical area or the population size. The patterns of consumption were stable over the week, except in Milan where the use of both substances decreased on Sundays, probably because there were no commuters. In Milan, the use of nicotine decreased from 2013 to 2015. There was a significant relationship between smoking and consumption of products containing caffeine (mainly coffee), thus in cities where more cigarettes were smoked, more caffeine was drunk. These results are generally in accordance with findings from epidemiological studies, but provide some additional local profiles of use and closely follow changes over the years. This information could be useful for healthcare professionals and policy-makers to monitor progress towards the reduction of prevalence in tobacco use, and set up new health campaigns.