What we could know about what you do in the loo

Poos and wees bring a deep sense of unease. This is not a modern phenomenon. Ancient Mesopotamian medical texts written in the 11th century BC describe Šulak, a toilet demon responsible for various diseases and aliments. Funnily enough, the name ‘Šulak’ is derived from the phrase ‘dirty hands’. Clearly, the ancient Mesopotamians knew of the risks lurking in our waste. While such mythological meanings have faded, human waste continues to pose serious health risks, with around one million people dying each year from waterborne diseases.

For most of us, poo and pee are something flushed and forgotten. For wastewater-based epidemiology (WBE), this is where the story begins.

The premise behind WBE is simple. The substances that we consume, like food and drugs, or are exposed to, (pollution, viruses) are processed in our bodies and excreted into wastewater systems with the flush of a toilet. Scientists can collect wastewater samples and analyse these for tiny chemical and biological markers that reflect aspects of human health and behaviour.

Government agencies around the world use WBE to monitor population health. In Aotearoa, at the height of the Covid-19 pandemic, wastewater was regularly collected from over 80 percent of the population. The data helped track the spread of the virus and guide public health responses such as targeted testing resources and lockdowns. Since 2019, our wastewater has also been monitored by the police for methamphetamine, cocaine and MDMA. Chances are that your toilet flush has been a part of this analysis.

Given that the findings of WBE can have tangible implications for how public health is understood and managed, what are the ethics of wastewater testing stemming from the growing interest of public and private institutions in WBE.

Informed consent is foundational to medical and research ethics and ensures that people can freely decide whether to participate. In WBE, individuals aren’t required to give informed consent because material is not directly collected from individuals.

Legal precedent, such as the landmark 1990 Moore v. Regents of the University of California case, has generally held that bodily materials, once discarded, no longer remain the property of the individual. The implication for WBE is that once you flush the loo, you relinquish the rights to whatever was flushed.

As the law stands, the way for you to opt out of WBE is to not use a toilet.

In practice, this means that wastewater utilities rather than individuals are largely responsible for granting permission for sampling. The lack of consent and formal ethical oversight leaves the door open for misuse by academic, state or private interests. As social medial scholars dannah boyd and Kate Crawford remind us in their research on the perils of Big Data: “Just because it is accessible does not make it ethical.”

Some have argued that in lieu of getting informed consent, WBE practitioners should ensure their work is cognisant of and respond to community concerns and values. Defining a community, however, is tricky. Wastewater catchments, the areas connected to a wastewater treatment plant, are largely fixed in place, yet people are not.

Critically, whose voices count? Marginalised and minority voices are likely to be excluded from such conversations about WBE. Different groups may view the risks of WBE in very different ways. For example, indigenous communities or ethnic minority groups may have particular or heightened concerns regarding the risks of WBE, rooted in the historical and lived experiences of state surveillance.

WBE has traditionally been considered a low-risk form of surveillance. Sampling has historically been conducted at large wastewater treatment plants, so findings can’t be traced back to individuals, let alone specific neighbourhoods.

During the Covid-19 pandemic, however, interest grew in targeted WBE in high-risk areas such as neighbourhoods, universities, hospitals and travel hubs, to identify infection clusters.

Advances in small-scale automated sampling devices are only making such applications more feasible, but there are ethical risks. If the findings of WBE can be tied back to specific neighbourhoods or buildings, this can perpetuate discrimination and stigmatisation. One only has to notice the tendency of some media outlets to label towns as ‘the meth capital of New Zealand’ when reporting on WBE to see the potential risks of such small-scale sampling.

While academic and public institutions have approached small-scale sampling for illicit drugs with considerable hesitancy, likely reflecting an awareness of these risks, the rise of privately driven WBE is changing this.

Private biotechnology companies are seeing the commercial opportunities of WBE, offering services from sample collection and analysis through to data interpretation. These companies have marketed their ability to zoom in on small populations. For example, some prisons in the United States have contracted private companies to sample wastewater for SARS-CoV-2 (the virus that causes COVID-19). Similarly, Biobot Analytics, a private biotechnology company, recently monitored wastewater for patterns of opioid consumption in small neighbourhoods (fewer than 7,000 people) across Detroit.

Of particular concern is where small-scale WBE could inform punitive law enforcement practices. In the U.S.’ current political climate, WBE performed at immigration detention centres could fuel anti-migrant rhetoric espoused by Trump. Detections of infectious disease markers in wastewater (i.e., monkeypox, hepatitis, tuberculosis etc) at immigration detention centres could provide the ammunition for authorities to turn away asylum seekers and other migrants.

This is not some distant, dystopian hypothetical. During the COVID-19 pandemic, Under Title 42 of U.S. Code 265, Trump’s conservative administration used the perceived threat of communicable disease as justification to expel asylum seekers and other migrants arriving at U.S. borders without prior authorisation. Title 42 is no-longer in effect, but Trump’s administration has indicated a desire to reinvoke this authority citing the perceived risk that mass migration poses for the spread of communicable disease. It is not hard to see how privately driven WBE conducted at these politically charged sites could lead to such Orwellian futures.

In response to these concerns, some have advocated for community-based WBE models, where those under surveillance have meaningful input into the decision-making process surrounding what questions WBE are seeking to achieve and how the data are to be used. Similarly, indigenous data sovereignty has emerged as a lens to reconsider how data collected on historically over-surveyed communities can remain under the stewardship of such individuals.

Jeff Goldblum’s character in Jurassic Park famously quipped that “Your scientists were so preoccupied with whether or not they could, they didn’t stop to think if they should.” This is not to say that WBE and the de-extinction of dinosaurs share the same ethical risks or that WBE practitioners are uncritical in their practice. (PHF Science, formally ESR, have written on the ethical development of WBE in Aotearoa).

Still, the cautionary note is apt. To begin to develop the ethical infrastructure to govern both private and public applications of WBE, the fundamental questions we need to ask are who decides what we monitor and for whose benefit are the data used.