Alcohol, nicotine, and caffeine consumption on a public U.S. university campus determined by wastewater-based epidemiology

Alcohol, nicotine, and caffeine use in at-risk populations is a public health concern that claims over 550,000 lives annually. Self-reported surveys from college students often reveal overconsumption of these substances. Unfortunately, the costs of these surveys are high, and consequently, the results from few studies are often extrapolated across the entire target population. Here we employed wastewater-based epidemiology (WBE) to directly measure the levels of these three psychotropic substances and their metabolites in sewage from a large public Southwestern U.S. university campus during the 2017–2018 academic year. Results showed per person alcohol consumption was 11.3 ± 7.5 g d⁻¹ person⁻¹ or 0.8 ± 0.5 drinks d⁻¹ person⁻¹, similar to averages of nationwide estimates from self-reporting of this subpopulation aged 18–25 years (10.1 ± 0.8 g d⁻¹ person⁻¹ or 0.7 ± 0.06 drinks d⁻¹ person⁻¹). Caffeine and nicotine consumption determined by WBE were significantly lower (p < 0.05) than nationwide estimates from self-reporting (caffeine: 114 ± 49 vs. 178 ± 19 mg d⁻¹ person⁻¹; nicotine: 627 ± 219 vs. 927 ± 243 μg d⁻¹ person⁻¹). Strong positive correlations were found for consumption of alcohol and nicotine (Spearman r_s: 0.71; p < 0.01), and nicotine and caffeine (0.59, p < 0.01), but not alcohol and caffeine (0.17). Alcohol and nicotine consumption were significantly higher on weekends compared to weekdays (p < 0.01), while caffeine consumption was higher during the week (p < 0.05). This first U.S. WBE study on alcohol, nicotine, and caffeine use among U.S. college students demonstrated the feasibility and practicality of longitudinally tracking the behavior of an entire campus population of 60,000 students directly, repeatedly, and more inexpensively (US$0.58/person) compared to conventional questionnaires (US$127/person).