Pfas, a weapon to eliminate them in the microbiome

Some bacteria in our intestines can absorb and store Pfas molecules, the substances that have hit the headlines in recent days due to the ruling of the Vicenza Court of Assizes that convicted 11 people for the well-known case of pollution in the waters of some provinces in the Veneto region.

The discovery is due to research coordinated by the University of Cambridge and published in Nature Microbiology , according to which increasing the presence of these species in the intestinal microbiome could protect us from the harmful effects of PFAS.

What are PFAS and why are they harmful?

Pfas is an acronym for perfluoroalkyl and polyfluoroalkyl substances, and this name includes over 4,700 man-made chemicals known to pose a health risk. Found in many everyday items, such as non-stick pans, cosmetics, waterproof clothing and food packaging, they are widely used for their resistance to heat, water, oil and grease. However, because they take thousands of years to decompose (they are therefore defined as “perennial”), they are accumulating in large quantities in the environment and, consequently, in our bodies.

Like a slow poison

When they enter our bodies, some PFAS are eliminated through urine within a few days, but others, which have a longer molecular structure, can remain in our bodies for years. And they have been linked to a range of health problems, including reduced fertility, delayed childhood development, and an increased risk of certain cancers and cardiovascular disease. “We are all exposed to PFAS through our water and food: these chemicals are so widespread that they are present in all of us,” commented Anna Lindell, first author of the new study. “They were once considered safe, but it is now clear that they are not. It took a long time for PFAS to be noticed, because at low levels they do not show toxicity. But they are like a slow poison.”

Bacteria as sponges for PFAS

In the new study, researchers were able to identify bacterial species naturally present in our intestines and capable of absorbing different Pfas molecules from the surrounding environment. To test this ability, the team introduced them into the intestines of some mice to make their microbiome more similar to ours. Subsequent analyses revealed that 9 strains of bacteria rapidly accumulated the Pfas ingested by the rodents, which then eliminated them through their feces. Like a sort of sponge, in fact, the bacteria absorbed them, preserving them inside them, in what in technical jargon is defined as bioaccumulation. Not only that: from in vitro studies, researchers noted that by increasing the levels of Pfas, the bacteria worked even more intensely, constantly removing the same percentage: within 24 hours of exposure, the bacterial species examined absorbed between 25% and 74% of Pfas. "We found that some species of human gut bacteria have a remarkably high capacity to absorb PFAS from the environment at different concentrations and store them in aggregates," explained Kiran Patil, one of the authors of the study.

Towards new methods to eliminate PFAS

The study provides the first evidence that our gut microbiome may play an important role in eliminating these toxic chemicals. A finding that, if demonstrated directly in humans, could one day pave the way for the potential development of new methods to defend ourselves from PFAS, such as the use of probiotics capable of increasing the levels of beneficial bacteria in our intestines. "We have not found a way to destroy PFAS," Roux concludes, "but our findings open the possibility of developing methods to eliminate them from our bodies, where they cause the most damage."