The ‘forever chemicals’, previously linked to multiple health hazards, are actually ubiquitous, with a new US study finding them in 98.8 percent of 10,566 blood samples tested.
Technically, the timeless chemicals are per- and polyfluoroalkyl substances (PFAS), of which more than 15,000 are known to toxicologists. The nickname “eternal” refers to its resistance to breaking and tenacity in the environment.
These chemicals have been widely used in a variety of manufacturing processes for decades, making their way into our food, water supply, and Earth’s ecosystems.
We already knew that PFAS could enter the human body. In this new analysis, researchers at NMS Labs, a US toxicology laboratory, wanted to find out how many different combinations of PFAS are present in blood.
PFAS are found in many products, including nonstick pan coatings. (Gregory DiSalvo/iStock/Getty Images Plus)
Data for this report was derived from 10,566 serum and plasma samples submitted to NMS Labs in Pennsylvania for PFAS testing.
“This large dataset provides a real-world snapshot of how multiple PFAS occur simultaneously in humans,” said NMS Labs toxicologist Laura Labay.
The dataset used did not specify whether multiple samples were collected from the same person, but represents a large sample of the U.S. population that researchers analyzed using existing PFAS testing panels.
“By identifying these common exposure patterns, this study provides a deeper understanding of what widespread and combined PFAS exposure means for human health,” added LaVey.
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The researchers found that just 0.18% of the samples contained a single PFAS chemical. Most samples contained complex mixtures of multiple PFAS chemicals.
“Evaluation of chemical mixtures is important when assessing biological effects because of potential additive, synergistic, or antagonistic interactions,” LaVey and fellow toxicologist Lee Bloom from the NMS Institute wrote in the paper.
Many of the same PFAS were detected in most blood samples. One of the chemicals, perfluorohexane sulfonic acid (PFHxS), is used in textiles, furniture, and adhesives and was detected in 97.9% of the samples tested.
Health concerns related to PFHxS, including effects shown in animal studies on the liver and immune system, have now restricted or outright banned its use in many countries, but the damage may already have been done.
Most people have likely been exposed to a variety of PFAS, with researchers still trying to understand the combined effects of multiple PFAS chemicals.
As PFAS are manufactured and used, they can migrate into soil and water. (MI DEQ)
“These findings confirm that exposure to PFAS rarely occurs as isolated compounds,” Labay said.
“Instead, individuals typically carry a body burden containing five or more PFAS with different bioaccumulation properties and half-lives.
“The high prevalence and consistency of certain PFAS combinations highlights the importance of mixture-based interpretation in biomonitoring, especially given the potential for PFAS to affect multiple biological systems in the body.”
The researchers primarily tested the 13 most common PFAS, so their results may underestimate the overall chemical burden.
However, it’s worth keeping in mind that this study did not measure levels of PFAS, only whether they were detectable using mass spectrometry.
It’s not yet clear how much permanent exposure to chemicals is enough to cause us harm. What we know so far about the effects of PFAS comes from cell and animal models and observational studies, with a growing body of evidence.
Studies have linked PFAS to accelerated cellular aging, changes in the brain, and increased risk of some types of cancer, but no direct causal link has been established.

Part of the problem here is that PFAS are very useful. They protect the product from water, heat and oil, but these benefits also mean that the product takes a long time to break down once it enters the environment.
Although regulators and governments take the potential dangers seriously, it is difficult, if not impossible, to permanently ban the use of these chemicals, find safe alternatives, or remove them from the environment.
Related: Babies are exposed to 42 ‘permanent chemicals’ before birth, study finds
What these new discoveries show is how widespread this problem is and how many different cocktails of potentially toxic substances we are dealing with. Across the two test panels used, more than 70 unique PFAS combinations were detected.
“We hope these findings will help inform future risk assessment efforts, guide research on hazardous PFAS mixtures, and ultimately support clearer clinical and public health guidance,” LaVey says.
This research Occupational Environmental Health Journal.

