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It sounds like science fiction, but researchers are getting better and better at retrieving tiny traces of human genetic material called environmental DNA — or eDNA — that we leave floating in the air or water, and mining it for genetic info.

The technique has technically been around for a while, and has been used for a number of purposes including detecting the virus that causes COVID-19  in wastewater, or tracking endangered or invasive species.

But now, a team of scientists has attempted to see how much information it could glean from human eDNA specifically, The New York Times reports, analyzing samples for genetic markers related to genealogy and even ethnicity.

As detailed in a new paper published in the journal Nature Ecology & Evolution, a team led by University of Florida wildlife geneticist David Duffy found that they could trace back medical and ancestry information from these minute traces of human DNA.

And that has privacy experts deeply worried, the NYT notes, especially in the context that law enforcement has already been making use of flawed and controversial DNA tools to identify suspects.

Duffy and his team were originally looking for tiny segments of sea turtle DNA to track diseases affecting the species. But upon discovering "surprising" amounts of human eDNA as well, the team shifted gears.

In a series of experiments, the researchers took samples from a creek in Florida and analyzed them for traces of DNA. They found far more legible human DNA than expected, including information pertaining to genetic ancestry.

One sample was even complete enough to be entered into the federal missing persons database, according to the report.

Experts believe that Duffy and his team's research could lead to new discussions surrounding the collection and analysis of human eDNA.

Harvard genetics researcher Anna Lewis told the NYT that the tech could one day be used to identify and perhaps even persecute specific ethnic minorities.

"This gives a powerful new tool to authorities," she said. "There’s internationally plenty of reason, I think, to be concerned."

Chinese officials have already conducted genetic research to study the DNA of the country's ethnic minorities, alarming experts. Analyzing traces of eDNA 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 20 genetic markers of any given suspect.

The error rate of identifying human DNA fragments is also still much higher than conventional techniques, meaning that the chances of false positives remain high.

But these limitations may not matter much when it comes to police looking for new ways of identifying suspects. While guardrails are in place for researchers at institutions, including an approval process and ethics boards, law enforcement most of the time operates with far fewer restrictions.

"It’s a total wild west, a free for all," Erin Murphy, a law professor at the New York University School of Law, told the NYT. "The understanding is police can sort of do whatever they want unless it’s explicitly prohibited."

More on DNA forensics: Police Say They Used Genealogy Database to Arrest Idaho Murder Suspect

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