Human DNA Is All Over the Place, Raising Privacy Concerns

Scientists have detected surprisingly high amounts of human DNA in wildlife environments, including seawater and air, a discovery that raises novel ethical concerns about genetic privacy, while also offering potential benefits, such as enhanced disease prevention, reports a new study.

Every habitat on Earth is littered with environmental DNA, or eDNA, which is made up of genetic fragments cast off by living things through normal processes, such as shedding skin, coughing, or defecating. Recent advances in eDNA research have produced dramatic breakthroughs that have helped scientists track human pathogens, monitor endangered species, and even explore ecosystems that existed two million years ago.

Whereas previous studies have deliberately looked for human eDNA at various sites, wildlife biologists at the University of Florida (UF) stumbled across troves of our genetic material almost by accident. The researchers initially set out to monitor endangered sea turtle populations as part of their work with UF’s Sea Turtle Hospital, but were astonished to find vast quantities of human eDNA in samples collected from water, sand, and air, according to a study published on Monday in Nature Ecology & Evolution.

“Our original research project consisted of the collection of water and sand in very small volumes from environmental sources such as sea turtle tanks, ocean water, and nesting beaches,” said Jessica Farrell, a sea turtle expert at UF and an author of the study, in a press briefing held on Thursday. 

“Given the power of eDNA approaches, we did expect to recover DNA from many species, including some human DNA, but we originally expected to have far more human eDNA recovered from human settings, like the turtle tanks at our hospital, rather than from samples taken from the environments,” Farrell continued. “We found that there was actually far more human eDNA in the environment, especially nearby rivers, rather than in the tanks at our facility, even though our turtle patients require a lot of hands-on care. This was our first clue that the level of human eDNA recoverable from environmental samples is far higher than we expected.” 

This “human genetic bycatch,” as the team called it, was not only more abundant than expected, it was also surprisingly high-quality, allowing the researchers to probe the ancestries and pathologies of local communities by sequencing eDNA. The results suggest that eDNA bycatch may emerge as a unique and powerful tool for fields like public health, wildlife conservation, archeology, and criminal forensics. 

“The quality of the human DNA in the environment means that it can likely be applied to a whole range of beneficial medical, environmental, and forensics applications,” said study author David Duffy, a UF professor of wildlife disease genomics, at the briefing. “For instance, in the medical sphere, eDNA could be used to look for pathogens in wastewater” or “could be applied to non-invasive routine cancer screening.”

“In terms of forensics, eDNA may have the potential to aid the solving of crimes,” he continued. “Finally, for us, it's useful that as we advance human eDNA applications, it will also help us better study wildlife and their diseases.”

However, human genetic bycatch may also enable nefarious activities, including surveillance of individuals or minority groups, or the collection of genetic information without the knowledge consent of local populations. Existing genetic databases have already contributed to human rights abuses and the commodification of genomic data, which is a particular concern to Indigenous groups. 

“The application of human eDNA approaches could further undermine genetic consent, limiting the ability of threatened minorities to withhold their genetic information,” the team said in the study. "In the future, human eDNA could also be utilized to determine whether members of a genetically distinct group were present in a given population—for example, through wastewater monitoring or air filtering at checkpoints, in urban areas or in private dwellings. Such potential is particularly chilling given the propensity of humans to carry out ethnic persecution and genocide throughout our history.”

Given these harrowing possibilities, the UF researchers hope that their work will raise awareness of the thorny implications of human eDNA, which represent one part of a wider conversation about the ethics of human genomics research.  

“It is clear that in the short term the convergence of massively powerful deep-sequencing technologies with improvements in ecological eDNA sample capture approaches raises serious questions about human genomic bycatch, requiring discussion and regulatory consideration from scientific, ethical, regulatory and social perspectives,” the team concluded. “Regulators, researchers, funders and other stakeholders should develop responses to the ethical implications of human genetic bycatch and intentional human eDNA applications.”