A peer-reviewed study published in Frontiers in Aging found that two specific “forever chemicals” detected in the blood of 95% of participants are linked to faster biological aging, with the strongest effects concentrated in middle-aged men. The research adds a new dimension to the known health risks of per- and polyfluoroalkyl substances, or PFAS, and raises pointed questions about who bears the greatest burden, particularly firefighters whose occupational exposure far exceeds that of the general population.
PFAS Linked to Accelerated Biological Clocks
The study, drawn from the National Health and Nutrition Examination Survey (NHANES) 1999-2000 cycle, analyzed blood samples from 326 adults aged 50 and older. Researchers measured serum PFAS concentrations using isotope-dilution tandem mass spectrometry and then compared those levels against 12 distinct DNA-methylation aging algorithms. These algorithms estimate “epigenetic age,” a measure of how old a person’s cells appear at the molecular level, regardless of their birth date. When epigenetic age runs ahead of chronological age, the gap is called epigenetic age acceleration, or EAA, a pattern tied to higher risks of cardiovascular disease, neurodegenerative disorders, and all-cause mortality.
Two compounds stood out. PFNA (perfluorononanoic acid) and PFOSA (perfluorooctane sulfonamide) were detected in 95% of the study’s participants, and higher blood levels of both chemicals were strongly associated with faster biological aging. PFNA showed especially pronounced associations with EAA across multiple epigenetic clocks. A separate, independent analysis of 262 NHANES participants corroborated the finding, reporting that doubling PFNA concentration corresponded to higher EAA among males across several clock models. That sex-specific pattern is significant: the PFAS-aging link was not observed in women in either study, suggesting hormonal or metabolic differences may buffer or redirect the effect.
Why Middle-Aged Men Face the Sharpest Risk
The sex disparity is one of the study’s most striking results. Effects of PFAS on EAA differed by both sex and compound, but the consistent finding was that men, especially those in midlife, showed the clearest acceleration. Previous NHANES-based research had already suggested that higher PFAS blood concentrations tend to track with faster biological aging, but the new work narrows the risk profile. “These findings suggest that some newer PFAS alternatives are not necessarily low-risk replacements and warrant serious attention,” the study’s authors noted in a Frontiers press summary. That comment is directed at regulators and manufacturers who have marketed newer PFAS variants as safer substitutes for legacy compounds like PFOA and PFOS.
The biological plausibility is well established. Federal toxicological reviews have identified immune disruption, endocrine interference, and altered lipid metabolism as pathways through which PFAS affect human health. The CDC’s Agency for Toxic Substances and Disease Registry links PFAS exposure to cholesterol changes, weakened vaccine antibody responses, liver enzyme alterations, pregnancy complications, and certain cancers. Accelerated epigenetic aging could represent a unifying mechanism (one that helps explain why PFAS exposure correlates with such a wide range of chronic diseases). If PFAS are pushing cells to age faster at the molecular level, the downstream consequences would logically span multiple organ systems.
Firefighters Carry a Disproportionate PFAS Burden
The “one group” facing extreme risk in this story is firefighters. A study of 290 firefighters across four U.S. municipal departments found that multiple PFAS compounds, including PFHxS, PFOS isomers, PFOA, and PFNA, were elevated compared to matched NHANES participants in at least two of the four departments. A smaller study of 38 firefighters similarly reported elevated PFHxS levels relative to the general population. The exposure route is direct: aqueous film-forming foam, or AFFF, used to suppress fuel fires has historically contained high concentrations of PFAS, and firefighters absorb these chemicals through skin contact, inhalation, and contaminated gear.
Research from the University of Arizona Health Sciences, published in 2025, reinforced these findings and extended the concern beyond fire stations. “Our study reinforces previous research showing elevated PFAS levels among firefighters and suggests that health care workers may” also face increased exposure, according to the university’s release. Certain subpopulations experience higher PFAS exposures than the general population through point-source contamination, whether from industrial sites, military bases, or workplaces where PFAS-containing products are routine. When layered on top of the new aging data, the implication is clear. Firefighters are not only absorbing more of these chemicals but may be aging faster at the cellular level because of it.
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*This article was researched with the help of AI, with human editors creating the final content.
