Stress does not affect only the mind; it leaves chemical traces in many places throughout the body, including blood, saliva, and hair. A new study analyzing “university sewage” found that traces of the stress experienced by students during university examinations were present in the wastewater.
Wastewater surveillance captures multi-marker responses to short-term examination stress in a university population | Nature Water
https://www.nature.com/articles/s44221-026-00735-5
University Exams Produce a Distinct Chemical Signature in Sewage, Study Suggests : ScienceAlert
https://www.sciencealert.com/university-exams-produce-a-distinct-chemical-signature-in-sewage-study-suggests
Hearing about “sewage analysis” may sound strange, but the chemical composition of sewage, in which the excrement of many people accumulates, is known to vary by region and building. For example, past studies examining sewage in affluent and poor areas have shown that substances such as biomarkers associated with raw vegetables and fruit, ingredients of antidepressants and painkillers, and caffeine differ according to a region's affluence.
Differences Between Affluent and Poor Areas Revealed by “Substances in Sewage” - GIGAZINE
In this study, a research team from the University of Queensland in Australia analyzed sewage from a campus in Australia used by approximately 30,000 people, comparing “samples collected during regular teaching periods” with “samples collected during examination periods.” The team also analyzed the composition of sewage collected from nearby residential areas for comparison.
The results showed that, compared with the teaching period, sewage collected on the university campus during the examination period had elevated concentrations of oxidative stress biomarkers known as 8-hydroxyguanosine (8-OHG) and 8-hydroxydeoxyguanosine (8-OHdG). Compared with sewage from neighboring areas, 8-OHG was found to exhibit a statistically significant increase in concentration.
The research team stated, “A clear and temporary rise in oxidative stress levels was observed during the examination period. This is consistent with the physiological and psychological strain expected to accompany academic assessment. Taken together, these findings suggest that examination periods are a major source of stress at the population level and can be objectively detected using wastewater-derived biomarkers.”
Oxidative stress biomarkers were not the only things that changed during the examination period. The sewage collected during the examination period suggested that greater amounts of multiple antidepressants had been consumed, with a statistically significant increase particularly observed for the antidepressant amitriptyline (Tryptanol).
The research team stated, “The consistent direction of changes in multiple antidepressants and their metabolites suggests an increase in antidepressant consumption on university campuses during the study period, but the evidence is not conclusive and remains only suggestive. This trend is broadly consistent with the known association between academic stress among university students and worsening symptoms of depression and anxiety.”
Meanwhile, no significant increase was observed in the use of ADHD medications and similar drugs during the study period, while consumption of caffeine and artificial sweeteners decreased. Alcohol consumption also decreased during the study period, with findings suggesting that it increased again after the study ended.
One caveat of this study is that university toilets are used not only by university students but also by faculty and staff, contractors, visitors, and others. Nevertheless, wastewater analysis is said to be an important tool for detecting fluctuations in stress and drug use.
The research team stated, “These findings provide proof of concept for using wastewater analysis to investigate dynamic stress-related responses at universities.”
