Even walking barefoot on the beach leaves genetic traces: Human DNA is found almost everywhere, a study shows. The scientists say that the genetic material can also be collected unintentionally during environmental DNA tests. The quality of this “human genetic by-catch” can enable identification and other conclusions to be drawn. Since the sequence data from environmental DNA studies can be freely accessible, data protection issues arise, say the researchers.
For several years, a genetic method has found its way into various areas of research: genetic material can be obtained from environmental samples, which can then be assigned to the organisms of origin. This is because every cell in the body contains the entire genetic material of a living being. As a result, genetic material from organisms can remain in their environment via tiny particles of skin or excreta. It can now be recorded, sequenced and analyzed very effectively using genetic engineering methods.
Environmental DNA studies are already being used successfully to explore biodiversity or to detect invasive species in habitats. Genetic traces in wastewater samples can also be used to track down human pathogens, and fossil environmental DNA can provide clues to the creatures of past ecosystems. The study by researchers led by Liam Whitmore from the University of Florida now shows once again how amazingly powerful the environmental DNA method is. Above all, however, the team draws attention to a previously unnoticed aspect of social relevance.
Human DNA is often included
The study was based on a research project dedicated to studying sea turtles using environmental DNA. The researchers obtain their sample material from the tracks of the animals on the beach. As they report, it became apparent that they are also collecting genetic material that is not actually their focus: human environmental DNA. This led to the question of what significance this "human genetic by-catch" could have and to what extent "relevant" information could emerge from the material. In order to investigate this aspect, the researchers specifically searched for human environmental DNA in samples from different places and substances and also carried out experimental studies.
As the scientists report, using the standard methods of environmental DNA research, they were able to detect high-quality human DNA in many samples that came from different places and from different contexts: in sea and river water, various substances and the air of rooms them on the human genome. The researchers even conducted a test on a remote island. No human DNA was found in samples from the pristine sandy beach. However, the team was able to easily extract DNA from the footprints left by the volunteers and use it to sequence parts of the volunteers' genomes. However, the trailblazers had expressly given their consent to this.
“Throughout the project, we were continually amazed at how much human DNA we were able to find and the quality of it. In most cases, it's almost as good as taking a sample from a person," says senior author David Duffy of the University of Florida at St. Augustine. Therefore, when reference material was available, the genetic material in the environmental DNA samples was sufficient to identify an individual. It was even possible to draw other conclusions – for example, about the parentage or even a tendency to certain diseases, the researchers report.
Importance of data protection law
According to them, a possible gap in data protection law in connection with environmental DNA studies is now becoming clear: "In science, it is common to make genetic sequences from investigations publicly accessible. So that also means that if you don't sort out the human information, anyone can use that information,” says Duffy. In the case of environmental DNA, however, there is usually no consent from those affected regarding the handling of their genetic information, the researcher emphasizes.
According to the team, scientists and regulators should now look at how to deal with the data, which can come from sources such as sewage, a shovel of sand or the air in the room. One possible approach would be to specifically detect and remove human sequences in data sets. “When we make technological advances, there are often useful things that the technology can be used for, but there are also worrying aspects. This is also the case in this case. We now want to draw attention to this early on, so that decision-makers and society have time to develop regulations,” concludes Duffy.
Source: University of Florida, professional article: Nature Ecology & Evolution, doi: 10.1038/s41559-023-02056-2