Wastewater-based epidemiology

Wastewater-based epidemiology (or wastewater-based surveillance or sewage chemical-information mining) analyzes wastewater to determine the consumption of, or exposure to, chemicals or pathogens in a population. This is achieved by measuring chemical or biomarkers in wastewater generated by the people contributing to a sewage treatment plant catchment. Wastewater-based epidemiology has been used to estimate illicit drug use in communities or populations, but can be used to measure the consumption of alcohol, caffeine, various pharmaceuticals and other compounds. Wastewater-based epidemiology has also been adapted to measure the load of pathogens such as SARS-CoV-2 in a community. It differs from traditional drug testing, urine or stool testing in that results are population-level rather than individual level. Wastewater-based epidemiology is an interdisciplinary endeavour that draws on input from specialists such as wastewater treatment plant operators, analytical chemists, molecular biologists and epidemiologists.

History Wastewater-based epidemiology (WBE) can be applied in the field of research that uses the analysis of sewage and wastewater to monitor the presence, distribution, and prevalence of a disease or chemicals in communities. The technique has been used for several decades, and an example of its early application is in the 1940s when WBE was applied for the detection and distribution of poliovirus in the sewage of New York, Chicago, and other cities. Another early application came in 1954, in a study of schistosome of snails. Wastewater-based epidemiology thereafter spread to multiple countries. By the turn of the 21st century, numerous studies had adopted the technique. A 2005 study measured cocaine and its metabolite benzoylecgonine in water samples from the River Po in Italy. Wastewater-based epidemiology is supported by government bodies such as the European Union Drugs Agency in Europe. Similar counterparts in other countries, such as the Australian Criminal Intelligence Commission in Australia and authorities in China use wastewater-based epidemiology to monitor drug use in their populations. As of 2026, WBE had reached more than 4600 sites in 72 countries.

Technique Wastewater-based epidemiology is analogous to urinalysis on a community scale. Small molecule compounds consumed by an individual can be excreted in the urine and/or feces in the form of the unchanged parent compound or a metabolite. In communities with sewerage, this urine combines with other wastes including other individuals' urine as they travel to a municipal wastewater treatment plant. The wastewater is sampled at the plant's inlet, prior to treatment. This is typically done with autosampler devices that collect 24-hour flow or temporally composite samples. These samples contain biomarkers from all the people contributing to a catchment. Collected samples are sent to a laboratory, where analytical chemistry techniques (such as liquid chromatography-mass spectrometry) are used to quantify compounds of interest. These results can be expressed in per capita loads based on the volume of wastewater. Per capita daily consumption of a chemical of interest (e.g. a drug) is determined as

R × F × C P {\displaystyle {\frac {R\times F\times C}{P}}}

where R is the concentration of a residue in a wastewater sample, F is the volume of wastewater that the sample represents, C is a correction factor which reflects the average mass and molar excretion fraction of a parent drug or a metabolite, and P is the number of people in a wastewater catchment. Variations or modifications may be made to C to account for other factors such as the degradation of a chemical during its transport in the sewer system. For microbial surveillance, methods from molecular biology like PCR (qPCR and dPCR) and genetic sequencing are used. These methods are often highly susceptible to inhibition by various chemical substances commonly found in wastewater. Monitoring of inhibition or removal of these inhibitors is therefore recommended.

Applications Commonly detected chemicals include, but are not limited to the following;

Temporal comparisons By analyzing samples taken across different time points, day-to-day or longer-term trends can be assessed. This approach has illustrated trends such as increased consumption of alcohol and recreational drugs on weekends compared to weekdays. A temporal wastewater-based epidemiology study in Washington measured wastewater samples in Washington before, during and after cannabis legalisation. By comparing cannabis consumption in wastewater with sales of cannabis through legal outlets, the study showed that the opening of legal outlets led to a decrease in the market share of the illegal market.

Spatial comparisons Differences in chemical consumption amongst different locations can be established when comparable methods are used to analyse wastewater samples from different locations. The European Monitoring Centre for Drugs and Drug Addiction conducts regular multi-city tests in Europe to estimate the consumption of illegal drugs. Data from these monitoring efforts are used alongside more traditional monitoring methods to understand geographical changes in drug consumption trends.

Microbial surveillance

… excerpt ends here. Continue reading the full article.