Caffeine levels as a predictor of Human mastadenovirus presence in surface waters-a case study in the Sinos River basin-Brazil

The presence of caffeine in environmental water samples is almost entirely human-related, given that there are virtually no industrial or agricultural releases. Caffeine has already been proposed as an anthropogenic marker for wastewater contamination of surface waters. The aim of this study was to evaluate if caffeine concentrations in water can be a predictor of virological and bacteriological contamination. Water samples were taken at three sampling sites from urban water streams from the hydrographic basin of the Sinos River (Brazil) monthly in the period of May 9th, 2016 to April 11th, 2017 (n = 36). Concentrations of Human mastadenovirus (HAdV-F and HAdV-C), fecal coliforms, and caffeine were measured in all collected samples. Concentrations of caffeine in water were strongly correlated with HAdV-F (r(s) = 0.704, p = 0.000). This study, for the first time, characterized caffeine concentrations in water as predictors of virus presence, with cut-off values presenting 92.9% specificity and 95.5% sensitivity for HAdV-F and 66.7% specificity and 80% sensitivity for HAdV-C. Considering its marked chemical stability and ease of quantification, caffeine concentrations can be used as a comprehensive marker of human contamination of water resources, also being predictive of bacteriological and virological concentrations.