Almost everyone reading this has PFAS in their blood. So do I. The CDC has been documenting this through the NHANES biomonitoring program since 1999, and the most recent data show detectable levels in more than 98% of Americans tested. That number does not describe a contamination event. It describes the baseline.
What has changed recently is not the exposure, which has been stable and global for decades, but the evidence base. A class of compounds that was treated as industrially essential and biologically inert for fifty years has steadily accumulated associations with cancer, thyroid disease, cardiovascular disease, liver damage, immune dysfunction, and reduced fertility. In 2022, the first randomized trial showed that some amount of this body burden could be reduced. In 2026, a mechanism paper from the University of Colorado Anschutz identified one specific PFAS compound as the likely worst actor during fetal development.
This series organizes what the science now supports, what it does not yet support, and where the clinical conversation should land for patients trying to make informed decisions. This first post is the entry point. The four that follow go deeper on specific angles.
What PFAS Are, Chemically
PFAS stands for per- and polyfluoroalkyl substances. The name is not important. The chemistry is.
Every PFAS molecule contains at least one carbon atom fully bonded to fluorine. The carbon-fluorine bond is one of the strongest in organic chemistry, roughly twice the bond energy of a carbon-hydrogen bond. Biology, which evolved to break down carbon-based molecules, has no meaningful toolkit for breaking carbon-fluorine bonds. Neither does soil chemistry. Neither does water. The bond was engineered by industrial chemists precisely because of this resistance, and that same resistance is why the compounds now persist in the environment, in groundwater, and in human tissue essentially indefinitely.
The EPA has identified roughly 15,000 unique PFAS compounds. Broader definitions, including the OECD's 2021 reclassification, identify millions. For clinical purposes, a few dozen are commonly measured, with names like PFOA, PFOS, PFHxS, PFNA, and PFDA. These are long-chain variants with biological half-lives measured in years: approximately 4.8 years for PFOS, 3.5 years for PFOA, and 5 to 8 years for PFHxS. Short-chain replacement compounds like GenX clear faster but also appear to have their own toxicity profiles, and the research is moving quickly.
This is the first thing that makes PFAS different from other environmental toxin discussions you may have read. Most environmental toxins are either rapidly metabolized (alcohol, most drugs) or slowly excreted (heavy metals). PFAS are neither metabolized nor efficiently excreted. Once inside you, they stay.
Why the Plasma Compartment Matters
The second thing that makes PFAS different is where they live in the body.
Heavy metals like lead and mercury lodge in bone and soft tissue. Lipophilic pollutants like PCBs and dioxins concentrate in fat. PFAS do neither. They bind to serum proteins, particularly albumin and liver fatty acid-binding protein, and circulate in plasma. This is why PFAS levels in serum are approximately twice the levels in whole blood: the compounds simply are not in the red cell compartment in any meaningful quantity.
Clinically, this matters because it determines what interventions can work. You cannot meaningfully reduce body burden of a plasma-bound toxin by exercising, sweating in a sauna, or taking oral binders. Those strategies make sense for some exposures. They do not make sense for this one. The compound is in a compartment you cannot access without moving plasma directly.
This is also the argument against whole blood donation as a PFAS intervention. Whole blood removal discards red cells along with plasma, which means you sacrifice iron and oxygen-carrying capacity to access the compartment where the toxins actually live. The Gasiorowski 2022 randomized trial confirmed this empirically. Over 12 months, plasma donation reduced PFOS by 2.9 ng/mL, which the study's lead author characterized as approximately a 30% decrease. Whole blood donation reduced PFOS by only 1.1 ng/mL, and had no significant effect on PFHxS at all. The difference is not small. It is the difference between a clinically meaningful intervention and an inefficient one.
What the Evidence of Harm Actually Shows
The evidence that PFAS exposure harms human health is no longer contested in the way it was a decade ago. The C8 Science Panel, convened as part of a West Virginia class-action settlement following DuPont's PFOA contamination of the Ohio River Valley, linked PFOA exposure to kidney cancer, testicular cancer, thyroid disease, ulcerative colitis, pregnancy-induced hypertension, and high cholesterol over eight years of epidemiological study of a large exposed population. Subsequent research has extended that list to include liver disease, cardiovascular disease, reduced vaccine response in children, endometriosis, polycystic ovary syndrome, and reduced fertility.
The individual effect sizes are generally modest. PFAS exposure does not act as a clean binary cause of any specific disease. What it does appear to do is shift the probability of adverse outcomes upward across multiple systems, a pattern consistent with a chronic low-level endocrine-disrupting exposure that acts through many mechanisms. The International Agency for Research on Cancer classifies PFOA as a Group 1 human carcinogen. In 2024, the EPA finalized enforceable drinking water limits for PFOA and PFOS at 4 parts per trillion, below what many municipal water systems can reliably measure without upgraded testing infrastructure.
The fertility and fetal development evidence is the subject of Part 5 of this series. Two independent research groups, one at Mount Sinai and one at the University of Colorado Anschutz, have now converged on the same specific PFAS compound (PFDA) as the likely worst actor, from completely different clinical endpoints. That kind of convergence is how scientific consensus begins to form.
Two independent research groups have converged on the same PFAS compound as the likely worst actor, from completely different clinical endpoints. That kind of convergence is how scientific consensus begins to form.
The Intervention Question
If PFAS are in nearly everyone's blood, if they persist for years, and if they are associated with meaningful harm across multiple organ systems, the obvious question is what can be done.
There are three honest answers, in order of evidence strength.
First, source reduction. Avoid the obvious exposures. Test your drinking water if your water system has not published recent PFAS data, and filter it if needed. Avoid PFAS-treated cookware. Read food packaging labels. This is the easiest intervention to recommend and the hardest to execute, because PFAS are so widespread that meaningful source reduction often requires significant lifestyle changes and, for many people, is simply not possible given where they live and what they can afford.
Second, plasma-compartment removal. The Gasiorowski 2022 trial is the only randomized controlled evidence that the body burden of PFAS can be reduced. Regular plasma donation works. Therapeutic plasma exchange, which moves substantially more plasma per session in a clinical setting rather than a donor center, has not been directly studied in a PFAS-specific RCT. The mechanistic argument for greater efficacy is straightforward: you are removing more of the compartment where the toxins live, in a single controlled session.
Third, a note on adjacent approaches. Activated charcoal, chelation therapies originally developed for heavy metals, saunas, and supplement protocols have not shown controlled efficacy for PFAS reduction. A 2025 paper in Medical Hypotheses (a venue for hypothesis-generating rather than primary peer-reviewed research) reported promising reductions across a panel of environmental toxins after serial plasma exchange, and those findings deserve follow-up.
The honest position is that the evidence base is growing, the directional arguments are sound, and the specific claims should be calibrated to what the studies actually support.
What This Series Covers
The four posts that follow go deeper on specific questions that readers with PFAS concerns tend to ask.
Part 2: TPE for Detoxification covers the broader environmental medicine frame. PFAS sit alongside heavy metals, microplastics, and other persistent pollutants, and the choice of intervention depends heavily on where a given toxin lives in the body. This is the entry point for readers thinking about environmental toxins more generally.
Part 3: The Jersey PFAS Crisis takes one of the most contaminated populations in the United States as a case study. It makes the full argument for why whole blood removal is the wrong strategy for protein-bound toxins, and why the distinction between plasma and blood matters more than most clinical conversations acknowledge.
Part 4: The Hidden Risk of Weight Loss covers a clinical scenario that catches many patients by surprise. Persistent organic pollutants stored in fat are mobilized into circulation during weight loss. Fat loss itself is healthy. The pollutants coming out of fat are not, and the intervention window for managing circulating levels is narrow.
Part 5: Fertility, Fetal Development, and the Conversation You Haven't Had With Your OB (coming soon) covers the newest and most mechanistically specific evidence. Two independent research groups have converged on PFDA as the single most harmful PFAS compound, from an adult fertility angle and a fetal craniofacial development angle. If you or a partner is thinking about conceiving, this is the post that matters most.
For a shorter, practice-voice treatment of the same material, the companion post on Global Apheresis covers the clinical case with the Gasiorowski RCT as the central evidence.
The Clinical Conversation
PFAS are not a novel problem or a niche concern. They are a ubiquitous class of chemicals that have been accumulating in human blood for six decades, that persist for years once inside the body, that concentrate in the plasma compartment rather than in cells or fat, and that now have associations with adverse outcomes across multiple organ systems. The evidence is no longer suggestive, and the intervention landscape is beginning to develop real RCT support.
The clinical conversation I want patients to have with their physicians starts here: do you know your exposure history, do you know your baseline PFAS levels, and what is the honest intervention plan given your individual situation? The answers are not the same for everyone. But the question itself is now defensible and evidence-anchored in ways it was not ten years ago.