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A new monitoring tool? Human DNA captured from the environment



(AFP) – Tracking people by following the genetic fingerprint they have sown in the environment: it will one day be possible, according to scientists who have captured human DNA in sand, water and even water. air, and fear drifts.

This discovery could lead to applications for medicine, the environment or forensic science. But it poses an ethical problem, given the ease with which these traces of human life were collected, warn the authors of the study published Monday in Nature Ecology and Evolution. Themselves surprised by the results of their work, they call for “safeguards” against invasions of privacy.

Recently developed, the environmental DNA technique is used to track wild species and better understand biodiversity. It consists of taking samples from the natural environments of animals, which leave genetic traces in their wake via the cells (skin, hair, scales, etc.) that they permanently lose.

Human beings are no exception to the rule, spreading their DNA – the carrier of genetic information specific to each individual – wherever they go: walking the beach, bathing, coughing and sputtering in the air. or by flushing the toilet…

Usually stealthy footprints, which scientists did not expect to capture on such a large scale, according to the study.

This “unwitting human genome grab” began in the Whitney Marine Biodiversity Laboratory at the American University of Florida, with sand swabs to study the environmental DNA of sea turtles.

The researchers expected to find some human DNA in the samples, which were often contaminated by the people handling them. But not in such large quantities, and of a quality “almost equivalent to that of a sample taken from a person”, explained David Duffy, a specialist in genetic diseases of wildlife at the University of Florida, who led the works.

– Omnipresent –

In the field, he and his team have found human genetic fingerprints almost everywhere: in the ocean and rivers around the laboratory, near urban centers and in less populated places, on the sand of isolated beaches…

Professor Duffy tested the technique in the cooler climate of Ireland, his country of origin, and unearthed human DNA by going up the course of a river – except at its source, far from any civilization.

In a veterinary hospital, the collection of ambient air samples revealed the presence of DNA corresponding to the personnel and to animal viruses, specifies the University of Florida in a press release.

The DNA sequences collected were long enough to be “readable”, making it possible to identify mutations associated with diseases, such as diabetes, and to determine genetic ancestry, said Mark McCauley, one of the main authors.

They were even able to sequence parts of the genome of volunteer participants who agreed to have their DNA sampled from their footprints in the sand.

“For ethical reasons, we have not reviewed our footage in such a way as to be able to identify specific individuals. But it is certain that this step will be taken one day. The only question is when”, commented Mark McCauley during of a press conference.

In the future, the collection of human environmental DNA could “benefit society”, for example by helping to detect cancerous mutations in sewage, or to identify the suspect of a crime which left no trace. more tangible trace like saliva or blood, according to this researcher at the Whitney laboratory.

But this raises as many hopes as “strong concerns about the protection of genetic privacy and the limits of policing”, notes Natalie Ram, professor of law at the University of Maryland. In a comment attached to the study, she points to a risk of “perpetual genetic surveillance”.

Concerns shared by the authors, who fear a misuse of the technique in particular to “track individuals or target certain ethnic minorities”. There is also the question of consent to collect data which “floats freely in the air”, underlines Mark McCauley.

“This is why we are now alerting scientists and society to consider our results and develop the necessary regulations to oversee research on human DNA”, insists Professor Duffy.

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