Our gut bacteria can absorb and remove toxic 'forever chemicals' — at least in lab mice

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Researchers have identified gut bacteria that can absorb toxic "forever chemicals" in lab mice, according to a new study, potentially offering up a way to control PFAS levels in humans.
PFAS, or perfluoroalkyl and polyfluoroalkyl substances, are synthetic chemicals used in a variety of products, from non-stick cooking pans to cosmetics. These substances are often nicknamed "forever chemicals" because they have strong chemical bonds that don't easily break down in nature and, in some cases, stick around for thousands of years. As a result, these chemicals pose a major pollution concern, both in our environment and in our own bodies.
Our drinking water and agricultural systems are already contaminated with PFAS to some degree, and as some of these chemicals can be absorbed through the skin and into our blood, there's no keeping them out of our bodies. Scientists are still untangling the health implications of PFAS, but exposure has been linked to various potential harms, including an increased risk of some cancers and disruptions to our immune system.
However, our bodies may also have a way of protecting themselves from these chemicals. The new study, published Tuesday (July 1) in the journal Nature Microbiology, investigated how human gut bacteria interacted with PFAS and found that nine species could effectively fend off the chemicals, at least in lab mice. The bacteria absorbed a good chunk of common PFAS that the mice were exposed to, which was then excreted in the mice's feces.
While there's a lot more work to be done, these findings suggest that we may be able to employ some bacterial species to control forever chemicals.
"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," study co-author Indra Roux, a researcher in the Medical Research Council (MRC) Toxicology Unit at the University of Cambridge, 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."
Related: How worried should we be about PFAS, the 'forever chemicals'?
PFAS resist water, oil and heat, making them useful in many different products. Today, there are thousands of different chemicals under the PFAS umbrella. While they are being phased out of some industries, like food packaging, many already exist in the environment and aren't going anywhere anytime soon.
To explore how gut bacteria interact with PFAS, the researchers first identified nine bacterial species that could absorb these chemicals and then gave those species to lab mice. The mice were then exposed to PFAS, including the common perfluorooctanoic acid (PFOA) and perfluorononanoic acid (PFNA). The bacteria absorbed between 25% and 74% of PFNA and 23% to 58% of PFOA, according to the study.
Accumulated PFAS didn't seem to affect the bacteria much. The PFAS aggregated (grouped together) in dense clusters within the bacteria, which appeared to minimize their impact on vital cell processes, according to the study.
"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," senior study author Kiran Patil, an investigator within the University of Cambridge's MRC Toxicology Unit, said in the statement. "Due to aggregation of PFAS in these clumps, the bacteria themselves seem protected from the toxic effects."
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The researchers noted in the study that their experiments involved giving mice a one-time dosage of PFAS, while humans — and other animals — typically experience low but chronic exposure to the chemicals.
Lawrence Wackett, a professor of biochemistry at the University of Minnesota Twin Cities who wasn't involved in the study, told Live Science in an email that the research was "particularly interesting" in light of another study published June 13 in the journal PNAS, which found that human gut microbial enzymes can break down carbon–fluorine bonds — the strong bonds present in PFAS.
"Taken together, there might be both sequestration and degradation of certain fluorinated compounds in the human gut," Wackett said.