A feasibility study on cortisol and cortisone as biomarkers for psychological stress in wastewater-based epidemiology

Psychological stress has a significant impact on individuals' quality of life and health. Traditionally, psychological stress assessment relies on self-reported tools such as the Perceived Stress Scale (PSS), which are inherently subjective. This study aims to evaluate the feasibility of using wastewater-based epidemiology (WBE) to assess cortisol and cortisone as biomarkers for psychological stress. We conducted sampling and monitoring of cortisol and cortisone concentrations at both a small-scale campus setting (five weeks) and a large-scale municipal wastewater treatment plant (12 months), calculating the mass loads of these hormones. At the campus level, while the mass load of cortisone was higher during exam weeks compared to regular class weeks, and higher in females than in males, no significant differences were observed in the mass load of cortisol. The mass load results of cortisone were consistent with the findings of the PSS-14 questionnaire. These results suggest that cortisone is a more suitable biomarker for psychological stress assessment. In the large-scale municipal wastewater samples, seasonal variations were observed, with higher levels of cortisol and cortisone in winter compared to summer, likely due to the COVID-19 outbreak in winter and the presence of external pharmaceutical sources. The results indicate that cortisone is more suitable for small-scale stress assessments, as larger-scale evaluations may be more significantly influenced by wastewater transport or sampling methodologies.