Old PFAS Went Down, but Replacement PFAS Are Rising in Blood
NonToxCo Research
Science & Safety Team · 4/7/2026
Legacy PFAS like PFOS and PFOA were phased out. But replacement PFAS are quietly building up in American blood. The problem didn't go away. It just changed names.
18 Years of Blood Samples Tell the Story
A 2026 study in Environ Sci Technol analyzed 156 serum samples collected between 2003 and 2021 in the United States. Instead of just testing for the usual PFAS, they used advanced screening to find chemicals nobody was looking for.
They found a concerning increase in 9Cl-PF3ONS, a chlorinated replacement for PFOS. Levels of 6:2 DiPAP and perfluoroalkyl phosphinic acids (PFPis) were also rising over time. They even discovered a completely new PFAS compound called Cl-PFNPA (chloroperfluorononylphosphonic acid) in human blood for the first time.
The Chemical Swap Game
When PFOS and PFOA got phased out, industry replaced them with newer PFAS compounds. These replacements weren't tested as thoroughly. Now they're showing up in people's blood and climbing over time. The old ones may be declining, but the total PFAS burden isn't going away.
Standard blood tests don't look for these newer compounds. Most people carrying them have no idea.
What You Can Do
Reduce exposure across the board. Don't rely on "PFOA-free" or "PFOS-free" labels. Those products may still contain replacement PFAS. Filter your water with activated carbon or reverse osmosis. Avoid stain-resistant and nonstick products. Choose naturally sourced materials. Browse non-toxic home essentials for PFAS-free alternatives.
Also see non-toxic kitchen essentials for safer alternatives.