Study Finds ‘Forever Chemicals’ In Nearly Every Blood Sample Tested, Rarely Just One

You Almost Certainly Have ‘Forever Chemicals’ in Your Blood. New Research Shows You Probably Have Several.

When researchers analyzed more than 10,000 blood samples, they found almost no sample contained just one so-called “forever chemical.” Nearly all of them contained several, and understanding what that combination means for human health is an urgent open question.

Per- and polyfluoroalkyl substances, or PFAS, are a large family of man-made chemicals used in everything from nonstick cookware to waterproof clothing to food packaging. Previous research has estimated that PFAS are detectable in the blood of roughly 99% of the global population. What this new study makes clear is that exposure almost never happens in isolation.

Published in the Journal of Occupational and Environmental Hygiene, the study found that 98.8% of all samples tested contained at least one PFAS. But the more notable finding sits just beneath that number: only 19 samples out of more than 10,000 contained just a single PFAS. Nearly every other sample contained multiple at the same time.

A Flood of Forever Chemicals: How PFAS Took Over

PFAS get their nickname because they don’t break down naturally in the environment or in the human body. Large-scale manufacturing began in the late 1940s, and use exploded throughout the 1950s as industries discovered how well they worked to create nonstick, waterproof, and heat-resistant surfaces. There are now more than 15,000 known varieties, spread so thoroughly through soil, water, and air that exposure has become nearly inescapable.

Exposure to PFAS has been linked to serious health concerns, including certain cancers, thyroid disruption, and developmental and reproductive problems. New Mexico has filed legal action against the U.S. Air Force over PFAS contamination that allegedly polluted drinking water serving tens of thousands of people, damaged crops, and led to the euthanasia of thousands of dairy cows that produced PFAS-contaminated milk. DuPont and a spinoff company agreed to a $670 million settlement in 2017 to resolve thousands of personal injury lawsuits tied to PFAS use at a West Virginia plant.

Doctors and clinicians tend to look at each chemical one at a time, treating each PFAS as its own separate concern. This study argues that approach may be incomplete, because the data show almost no sample carries just one of these chemicals at a time.

What Researchers Found in 10,000-Plus Blood Samples

Researchers at NMS Labs in Horsham, Pennsylvania, examined results from 10,566 blood samples submitted for PFAS testing between December 2023 and December 2024. Two laboratory panels were used. One screened for 13 different PFAS and accounted for 10,478 samples; the other screened for 18 PFAS and was used for the remaining 88 samples. Both panels used a highly sensitive detection method capable of identifying PFAS at very low concentrations.

Across the larger panel, researchers identified 58 unique combinations of PFAS chemicals. The smaller panel turned up 16 combinations. One particular cluster of six specific PFAS showed up in 2,754 samples, roughly one in four of all samples run through the 13-PFAS panel.

Why the PFAS Mix May Matter More Than Any Single Chemical

Looking at PFAS one at a time gives an incomplete picture of exposure. When two or more toxic substances are present in the body at once, their combined effect can be additive, meaning it equals the sum of the parts. It can also be synergistic, where the combination hits harder than each chemical would individually. In some cases it can be antagonistic, where one chemical reduces the effect of another.

Other research has begun to probe this concern. One study found that fish exposed to combinations of PFAS experienced broader developmental damage than those exposed to single compounds. Another found that human liver cells exposed to PFAS mixtures showed measurable toxic effects at concentrations that reflect real-world exposure. These findings suggest that evaluating each PFAS separately may underestimate actual health risks, though the science is still developing.

Standards or clinical interpretations that focus on one PFAS at a time may miss part of the exposure picture. EPA’s 2024 drinking water rules addressed certain PFAS collectively in limited regulatory contexts, and the National Academies of Sciences, Engineering, and Medicine has recommended that clinicians calculate the sum of several PFAS in blood when assessing potential additive effects in patients.

A Disconnect Between the Data and Current Practice

Across more than 10,000 samples, PFAS co-exposure appears to be the rule, not the exception. Decades of industrial use have made these chemicals nearly impossible to avoid, and this dataset makes plain that they almost never arrive alone. Researchers still don’t know exactly how harmful most of these specific combinations are, and the study did not measure health outcomes in the individuals tested. Still, the pattern is there. It appears virtually nobody is carrying just one of these chemicals.

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Disclaimer: This article is based on a published peer-reviewed study. Results reflect samples submitted to a clinical testing laboratory and should not be interpreted as a representative survey of the general population. A positive PFAS result does not necessarily indicate the presence or future development of a disease or other health condition.

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