Why the body struggles to clear PFAS
Many PFAS—per- and polyfluoroalkyl substances—are built around carbon–fluorine bonds. These bonds are unusually difficult to break through ordinary chemical reactions, so the body cannot readily dismantle the molecules the way it processes many nutrients or drugs. The liver does a great deal of chemical processing, but it does not have the tools to efficiently cut these bonds apart.
A ride through the bloodstream
Some PFAS bind to albumin, a plentiful protein in blood that normally carries substances around the body. Once attached, a PFAS molecule can circulate rather than being quickly filtered out and excreted. Binding to albumin is not the only factor in how long a particular PFAS remains in the body, but it helps explain why some can persist in blood.
This persistence is different from a substance simply staying in the environment. A person’s body can take in PFAS over time, and the balance between continued exposure and slow elimination affects the amount measured in blood. Biomonitoring has detected PFAS in the blood serum of 97% of Americans—a measure of how widespread exposure has been, not a sign that everyone has the same level or the same health risk.
Why persistence matters
When a chemical is broken down and cleared quickly, exposure may leave little trace. With persistent PFAS, even small, repeated inputs can contribute to a continuing presence because the body removes them slowly. That makes the bloodstream a record of both what has entered the body and how stubbornly certain PFAS resist leaving.
