The technology is technologically new, and has been used for a number of purposes, including detecting the virus that causes COVID-19 in waste water, or tracking endangered or invasive species.
A team of researchers is trying to see how much information it can glean from human eDNA specifically, The New York Times reports, by scanning the samples for genetic markers related to ancestry and even ethnicity.
As reported in a new paper published in the journal Nature Ecology & Evolution, a team led by wildlife geneticist David Duffy of the University of Florida found that they could infer medical and genealogical information from these microscopic traces of our DNA.
And, this has privacy experts very concerned, the NYT notes, especially in the context that law enforcement is already using flawed and controversial DNA tools to identify suspects.
Duffy and his team were originally looking for small segments of sea turtle DNA to detect diseases affecting the species. But upon discovering "surprising" amounts of human eDNA as well, the team switched gears.
In a series of researches, scientists collected samples from a bay in Florida and analyzed them for traces of DNA. They found much more legible human DNA than expected, including information related to genetic ancestry.
According to the report, one sample was complete enough to be entered into the federal missing persons database.
Experts believe that Duffy and his team's research could lead to new concerns regarding the collection and analysis of human eDNA.
Harvard genetics researcher Anna Lewis told the New York Times that the technology could one day be used to identify specific ethnic minorities and perhaps even persecute them.
"It gives officers a extra powerful new tool," he said. “I think there are a lot of reasons internationally to be concerned.”
According to experts, Chinese authorities have already conducted genetic research to study the DNA of the country's ethnic minorities. Analyzing eDNA traces could give totalitarian states even more power in that domain.
Fortunately, the traces Duffy found only capture one genetic marker at a time, whereas current law enforcement techniques involve identifying up to 20 genetic markers on any given suspect.
The error rate in identifying human DNA fragments is still very high compared to traditional techniques, meaning the probability of false positives remains high.
But these limitations don't matter much when it comes to police looking for new ways to identify suspects.
While guardrails have been put in place for researchers in institutions, including the approval process and ethics boards, law enforcement operates with very few restrictions most of the time.
"It's a complete Wild West, free-for-all," Erin Murphy, a law professor at New York University School of Law, told the NYT.
“The understanding is that police can do whatever they want unless it is explicitly prohibited.” Murphy added.