Certain types of microbes found in the human gut can absorb toxic “forever chemicals” from their surroundings, a new study has found.
When scientists introduced the microbes into the guts of mice to “humanize” their microbiome, they found that the bacteria rapidly accumulated the compounds consumed by the mice.
These so-called forever chemicals, also known as per- and polyfluoroalkyl substances (PFAS), were then excreted in feces, as documented in the study, published on Tuesday in Nature Microbiology.
“Given the scale of the problem of PFAS ‘forever chemicals’, particularly their effects on human health, it’s concerning that so little is being done about removing these from our bodies,” senior author Kiran Patil, head of the toxicology unit of the University of Cambridge’s Medical Research Council, said in a statement.
Notorious for their inability to break down in the environment, PFAS are linked to several kinds of cancers and other serious illnesses. There are thousands of types of PFAS, all of which are manmade and many of which are present in household items, such as nonstick pans, waterproof apparel and cosmetics.
“We found that certain species of human gut bacteria have a remarkably high capacity to soak up PFAS from their environment at a range of concentrations, and store these in clumps inside their cells,” Patil said.
“Due to aggregation of PFAS in these clumps, the bacteria themselves seem protected from the toxic effects,” he added.
To draw their conclusions, the researchers assessed the ability of two mixtures of human bacterial strains to sequester pollutant compounds — testing 42 common contaminants based on their reported occurrences in food.
They found that a total of 13 pollutants were depleted by more than 20 percent by one or both synthetic communities.
The scientists then tested 10 contaminants for depletion against 14 individual strains, which were a subset selected for their prevalence and abundance in a healthy population. In that test, they found that seven pollutants were depleted by more than 20 percent by at least one of the bacterial strains.
Among the pollutants degraded by the gut bacteria were PFOA and PFNA, two types of PFAS, the authors determined. PFOA and PFNA bioaccumulated in nine strains of bacteria, doing so at rates between 25 and 74 percent for PFNA and between 23 and 58 percent for PFOA.
Although the scientists identified the ability of the bacteria to uptake these forms of PFAS, they acknowledged that they have yet to pinpoint the mechanism by which the bacteria take up the contaminants.
But by uncovering microbial PFAS bioaccumulation, they expressed hope that their findings would provide a framework for future such investigations into the relationships between PFAS and the microbiome.
“The reality is that PFAS are already in the environment and in our bodies, and we need to try and mitigate their impact on our health now,” co-author Indra Roux, a researcher in the Toxicology Unit, said in a statement.
“We haven’t found a way to destroy PFAS, but our findings open the possibility of developing ways to get them out of our bodies where they do the most harm,” Roux added.
Building off their research, Patil and co-author Anna Lindell co-founded a startup, Cambiotics, to develop probiotics that remove PFAS from the body. They are investigating ways of turbo-charging the performance of these microbes, with the support of the University of Cambridge’s innovation arm.
“PFAS were once considered safe, but it’s now clear that they’re not,” Lindell said. “It’s taken a long time for PFAS to become noticed because at low levels they’re not acutely toxic. But they’re like a slow poison.”
