Forever Chemicals May Damage Kidney Function, Evidence Shows

Forever chemicals are falling in the rain, running through our waterways, and swimming in our bloodstreams, and now, initial research suggests these potentially harmful pollutants are 'clogging up' a crucial drainage system in our bodies.

The new study indicates forever chemicals are impacting kidney health, with changes to the gut microbiome explaining at least some of the effects.

Kidneys filter excess water and toxins out of the bloodstream, and forever chemicals are now circling these two 'drains' in a worrisome way. While evidence is currently limited, there is a chance that pollutants gathering in the kidneys are driving chronic disease, as well as cancer.

In rodents, when some forever chemicals accumulate in the kidneys, the high concentrations lead to injury via oxidative stress.

The new research on humans is the first longitudinal study to explore how forever chemicals might impact kidney function in a multi-ethnic cohort of young adults at high risk of metabolic diseases.

The proof-of-concept tracked 78 participants, aged 17 to 22, who were predominantly Hispanic. Those with greater exposure to seven different forever chemicals – indicated by blood samples collected at the start of the trial – showed signs of relatively poorer kidney function four years on.

For every standard deviation increase in their overall exposure, there was a 2.4 percent drop in serum creatinine, a blood marker that hints at how well the kidneys are filtering waste and extra water.

That's a small yet concerning finding, as young adulthood is a "critical development window for kidney function," write the authors of the study, led by scientists at the University of Southern California, Los Angeles.

Per- and polyfluoroalkyl substances (PFAS) are known as forever chemicals because they resist degradation and stick around in the environment and in us for a scary long time. The synthetic chemicals are used in non-stick cookware, fabric treatment, cosmetics, and food packaging, and they can be absorbed through the skin, inhaled, or swallowed.

Today, they are virtually impossible to avoid, and while only two chemicals (PFOA and PFOS) are clearly linked to cancer, cardiovascular disease, fertility issues, and birth defects, there are more than 12,000 variants on the market today with largely unknown health effects.

In the early 2000s, PFOA and PFOS were phased out of production in the US, after they were linked to toxic effects in several key organs at low concentrations.

More than two decades later, both PFOA and PFOS are still circulating in the blood of young people. The current study is only small and relies on imperfect measurements of kidney function, but it is a proof-of-concept for how scientists can measure organ damage from forever chemicals in the future.

Blood samples taken at the beginning and end of the trial, as well as stool samples provided by 45 participants, indicate at least some forever chemicals are impacting kidney health via the gut microbiome.

In the four-year trial, changes to just one group of gut bacteria and its blood metabolites explained 33 percent of reduced kidney function linked to forever chemicals. Another group of gut bacteria explained 50 percent of the changes.

"We saw that exposure to PFAS was potentially altering the composition of the microbiome, associated with lower levels of beneficial bacteria and lower anti-inflammatory metabolites," explains public health scientist Hailey Hampson from USC.

"This points to inflammation and oxidative stress as a potential mechanism, so that's an area where future research can focus."

Further studies are needed to understand how some forever chemicals are impacting the kidneys, but researchers say their findings provide evidence that damage may be partly ascribed to alterations in the gut microbiome.

The study was published in Science of the Total Environment.