Two media stories this week raised a stink about post-pandemic personal privacy as more sensors sniff out our secrets. The first discussed public analysis of wastewater for public health purposes. The other covered the use of dogs as disease detection systems. Both describe exposure of public action in realms once thought clearly to be personal and private.

The issue in both cases is biomarkers – a measurable substance in an organism – in this case a person – whose presence is indicative of some phenomenon such as disease, infection, or environmental exposure. In first instance, human liquid and solid waste is being tested right now to measure the spread of COVID-19 variants, find residual evidence of opioid abuse, and note the continued recycling of polyhalogenated chemicals in our water supply. In the second instance, trained dogs, using their spectacularly sensitive olfactory processes, can screen humans very effectively for pandemic diseases or virtually any cancer with a quick sniff and an immediate result. Did you ever think you needed to worry because your biomarkers are showing? Until now, you may not have known it was possible.

Biometric capture can be concerning to individuals and legislators. Measurements of your body and physical activities can be used to conclusively identify any of us, and we are learning the risks of biometric databases as the Afghani Taliban takes over U.S. biometric systems with information on millions of Afghan citizens. But biomarker analysis can be even more insidious, as it includes a gloss of analysis and social interpretation on top of an identifiable reading.  Biomarkers can tell us not only who a person is, but what processes are occurring within that person’s body. This leads to a different level of privacy threat, making conclusions about your body’s exposures and pathologies – including behavior-related activities – that would be difficult or impossible with simple biometric identification.

This week in Slate, epidemiologist Rolf Halden writes in detail about what biomarkers are being collected from our toilets and what the government and academics are learning from them. He notes that humans have examined evidence of disease in excretion for thousands of years, and examination of waste water by public authorities has led to quashing of oncoming pandemics of diseases like polio. He writes, “Defining where population monitoring ends and surveillance of individuals begins is important but surprisingly difficult. For common biomarkers excreted by just about every individual, such as caffeine and stress hormones, mingling of the excreta of a few individuals is sufficient to make tracing back the signal to an individual utterly impossible. But beware, if you were the only user of a medical imaging contrast agents or if someone had poisoned you with a radioactive chemical, your mobility potentially could be traced by wastewater monitoring from one neighborhood or city to another.”

"Defining where population monitoring ends and surveillance of individuals begins is important but surprisingly difficult."

Rolf Halden, Epidemiologist

Halden states that, because of advances in the technology of isolating and reading biomarkers, and because of recent pandemic necessities, we are now diagnosing entire cities in hundreds of municipalities around the world. “Used responsibly and judiciously, this health threat radar protects populations including you and your loved ones; and while you remain anonymous and untraceable, the data collected are being used to extend your life expectancy and improve your quality of life.” But Haden nods to the possibilities of conducting such examinations on a smaller scale, say each apartment building or college dorm could be measured, making identifications much easier, and tying them to drug use or sexually-transmitted diseases.

An academic paper by Dr. Halden and others analyzes the ethics behind “the newly gained ability to extract and analyze genetic material from wastewater.” It is one thing to send your genetic material to a lab and pay for analysis.  In the medical context, this information is protected under law (though not in the recreational context). It would be another thing for governments, universities or businesses to begin analyzing genetic material at wastewater treatment plants, thus analyzing the building blocks of your life without your knowledge or permission. The professors in their paper note that both corporate and legal policies regarding privacy have been historically reactive rather than proactive, and that the pace of advancement of reading genetic data and biomarkers in human waste has outpaced the rules surrounding the activity. This may not be a pleasant topic, but that shouldn’t keep us from providing privacy limits before many more cities enter into the business of collecting information from our waste.

For other biomarker news, in his most recent episode of the Revisionist History podcast, called The Dog Will See You Now, Malcolm Gladwell discusses the use of dogs for detecting biomarkers for important diseases. He demonstrates that, rather than submitting ourselves to invasive, uncomfortable, slow tests for COVID-19 exposure, a trained dog sniffing all people entering a school, airport or theater could give us better information instantly. He even demonstrates that since dogs tend to err (not very much) on the side of false-positives, those people found to be positive could be confirmed to have COVID-19 with secondary testing and the rest of us could avoid the problem. Dogs are also superb discovery mechanisms for colon cancer and other deadly diseases that benefit from early detection. In this case, biomarkers wafting off of your skin can alert the examining dog to the existence of a disease.

We already use dogs in security and policing to sniff for drugs and guns, as well as their centuries-long use to track people both missing and hiding. So we should already be comfortable allowing a dog to assist public health officials to seek out evidence of problematic diseases. Certainly some doctors would be offended that an animal is knocking them from their godlike pedestals, but those doctors simply don’t have the same nose skills.  If the dog is better than our present technology, then use the dog.

Of course, privacy issues arise here too. Think about how people would feel about requirements for entering the workplace insisting they walk past a security machine to immediately search their bodies for evidence of communicable diseases or opioid use – not whether you were carrying things into the building in your pockets or briefcase, but whether your body itself contained the evidence. Seems like the kind of privacy invasion that would cause objections and probably should be discussed from a policy standpoint before it is implemented. A trained dog can be just such a sensing machine.

Clearly, sensing biomarkers in bodies or in human waste can help prevent the spread of disease and help with other health and safety issues. But are we ready for our own bodies to be scanned for our own good, and for the good of society?  I would suggest that, gross as it may be, a conversation about smelling your body and testing your excrement may be important for privacy now and in the future.