A new study shows that exposure to two specific 'forever chemicals' may accelerate biological aging, especially in middle-aged men.
These chemicals – PFNA (perfluorononanoic acid) and PFOSA (perfluorooctanesulfonamide) – are just two of the thousands of 'forever chemicals', or to use the more technical term, PFAS (per- and polyfluoroalkyl substances).
Used widely since the 1940s and 1950s, PFAS are found in raincoats, upholstery, non-stick pans, food packaging, firefighting foams, and much more.
This vast range of synthetic substances was specifically designed to be durable. They protect surfaces from water, fire, and grease, and can resist heat and corrosion.
But this quest for durability, we're finding, may have been a little too successful: The sturdy carbon-fluorine backbone common to all PFAS means they're expected to take up to a thousand years to break down.
That's a problem, because scientists are repeatedly linking PFAS to adverse health outcomes for humans who are exposed to them (which is, most likely, all of us).
International policies exist to cut production of a small number of 'legacy' PFAS. Just two are clearly linked to health issues, like cancer and cardiovascular disease, but with just a few molecular tweaks, industry can bypass existing restrictions by creating an entirely new PFAS that achieves similar outcomes.
More than 12,000 variants are still on the market. It's not that these other kinds of PFAS are necessarily safer; it's just that we don't know much about their specific health effects yet.
Now, a team led by researchers from Shanghai Jiao Tong University in China has revealed a significant link between faster epigenetic aging in middle-aged men, and two of these alternatives, PFNA and PFOSA, a precursor of PFOA.
"These findings suggest that some newer PFAS alternatives are not necessarily low-risk replacements and warrant serious attention regarding their environmental impact," epidemiologist Xiangwei Li says.
Li and his colleagues uncovered this link in a public dataset, which included 326 older men and women who enrolled in the US National Health and Nutrition Examination Survey in 1999 through 2000, and provided a blood sample.
As part of the original survey, these blood samples were screened for concentrations of 11 different types of PFAS.
Li and colleagues were also able to estimate participants' biological age at the time of blood collection, based on 12 recently developed 'epigenetic clocks'. These clocks assess the extent of DNA methylation, rather than the traditional measure of telomere length, as an indication of biological age.
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PFNA and PFOSA were present in the blood of some 95 percent of participants.
In 50- to 64-year-old men, a higher concentration of PFNA was a strong predictor of faster epigenetic aging by some measures, but not others. The same effect was not seen in women, though it's unclear why sex made a difference.
"We suspect that men may be at higher risk because the aging markers we analyzed are heavily influenced by lifestyle factors such as smoking, which can compound the damaging effects of these pollutants," Li suggests.
Exposure to PFOSA was also linked to biomarkers of aging, albeit slightly different ones.
"Midlife is a sensitive biological window where the body becomes more susceptible to age-related stressors, which may explain why this group responds more strongly to chemical exposure," epidemiologist Ya-Qian Xu says.
While the association is concerning, a study like this can't determine whether the PFAS actually cause accelerated aging, only that there's an association with some types. It may turn out that some other factor specific to men of this age affects both their exposure level and their rate of biological aging.
But it's worth noting that PFAS concentrations weren't significantly different between sexes or age classes, nor were any links found between biological age and the concentrations of other types of PFAS analyzed in the study. Which suggests something may be going on with PFNA and PFOSA that's specific to middle-aged men.
Until further research is carried out, we won't know for sure.
"To reduce risk, individuals can try to limit their consumption of packaged foods and avoid microwaving fast-food containers," Li suggests.
"Looking ahead, we are actively modeling how PFAS interacts with other common pollutants, as we need to understand the cumulative health risks of these chemical mixtures."
The research was published in Frontiers in Aging.