You’re reading Part V (the last part) in a 5-part series about sewage science. Catch up on Parts I, II, III, and IV before diving into this one.
In 2012, Christian Daughton proposed a new concept for wastewater analysis. Rather than analyzing sewage for the breakdown products of foreign substances we encounter or put into our bodies, like drugs or pesticides, researchers could instead seek out endogenous biomarkers – substances produced by the body in response to conditions of health and disease.
Endogenous biomarkers are powerful because they tell you exactly what you want to know. Instead of treating opioid use as a proxy for pain, for instance, you could directly capture the extent of pain by measuring a marker produced during periods of injury or stress. Endogenous biomarkers are also integrative, capturing exposure to various forms of stress rather than a single drug or contaminant.
One example of this is a class of biomarkers known as isoprostanes. Produced by the body in response to oxidative stress and inflammation, they are a widely accepted indicator for conditions such as diabetes, heart disease, and obesity. Yet isoprostane levels can also reflect chronic exposure to social or psychological stressors.
Like much of the rest of WBE, research on isoprostanes and other endogenous biomarkers is still in its early stages. There are also unique challenges. Many biomarkers like isoprostanes are produced at some level in healthy individuals. Thus, it’s important to establish a “reference range” of normal values seen throughout an entire population, already a complicated task for individual patients. Plus, finding a robust biomarker that points to a specific illness or condition is difficult – there is still debate about whether some well-established biomarkers, like cholesterol, have predictive value for the development of disease at all. If these questions can be addressed though, analyzing wastewater for endogenous biomarkers might come the closest to studying a community as an integral “patient”—one that is complex and constantly changing.
Wastewater-based epidemiology is highly interdisciplinary, traditionally operating at the intersection of environmental chemistry and drug epidemiology. The growing interest in analyzing wastewater for SARS-CoV-2 has brought in a third field to the mix: virology and microbiology. “We’re a small bunch, but everyone brings something different to the table,” said Bowes.
The small bunch may soon be getting bigger. “I think Covid has really gotten wastewater into media attention,” Dan Burgard said. Researchers hope that increased coverage will lead to greater investment and interest in WBE in the future. “We’re seeing a blast of wastewater analysis groups pop up all over now, because people are starting to understand the utility and how useful this can be,” said Devin Bowes.
From drug monitoring to virus testing to emerging uses for studying nutrition and daily stress, wastewater analysis paves the way towards an ideal that Daughton called a “biological passport,” a snapshot of not just the physical, but social, psychological, and economic health of a community. Amid a pandemic, data from wastewater analysis can provide peace of mind for people returning to school and work, empowering communities with data on COVID-19 spread in their own neighborhoods. The coronavirus has without a doubt been devastating for the nation. But its boost for wastewater-based epidemiology may help us confront health crises in the future.
Especially in the U.S., it has been tough to convince people of the value of sewage surveillance, Bowes said. “With Covid, more people are starting to see the value in wastewater testing to understand human behavior and health.”
“In the future, maybe it won’t be so much of an uphill battle.”
Putamen 