Some compounds crop up in almost every PFAS blood test. That’s equally true for tests we do and for the testing done by the CDC as part of their NHANES biomonitoring program. So what are these compounds, why are they so widely detected, and should you be worried?

A brief history of PFAS compounds

Before we look at the specific compounds we need to know a bit of history about PFAS. Per- and polyfluoroalkyl substances (PFAS) have been around for over 80 years. Originally, they were discovered by accident and viewed as something of a chemical oddity, but they soon became a key supply for the US war effort during world war 2. Then by the1950s they began to be widely used commercially. Some of the earliest commercial uses were in Teflon® and Scotchgard®.

PFAS as surfactants

Right from the beginning, chemists noticed that PFAS compounds behaved oddly in the presence of oil and water. This is because many PFAS compounds are powerful surfactants. Surfactants are substances that alter the surface tension of materials.

Some surfactants reduce surface tension, thereby making it easier to wet the material. These so-called wetting agents are frequently used in detergents to help improve performance. Other surfactants actually increase the surface tension. This means that water and oil will bead up and run off the surface rather than be absorbed.

Many PFAS compounds fall into this latter category. This leads to some of their most common applications.

Waterproofing agents: Fabrics covered in PFAS-containing durable water resistant (DWR) coatings will shed water helping keep them dry.
Stain-resistant coatings: Many PFAS surfactants help to keep fabrics clean by preventing grease and stains from penetrating the fabric.
Greaseproofing: PFAS is often used to make surfaces greaseproof. Think fast-food wrappers, baking paper, and even firefighter safety gear.

PFAS are often added to other compounds in order to impart these properties. Moreover, mixtures of PFAS are often used during manufacturing of these coatings.

Health concerns about PFAS

As early as the 1970s scientists began to notice a build up of some PFAS compounds in the environment. Two compounds stood out in particular: PFOS and PFOA (perfluorooctanoic acid). Not only were these compounds getting into the environment, they also seemed to bioaccumulate in wildlife. Nowadays, PFAS are also often referred to as “forever chemicals” because they are so hard to break down in the environment.

By the 1990s, these environmental concerns had grown to become health concerns. PFOS and PFOA are both classed as carcinogens by the International Agency For Cancer Research. And more broadly, PFAS chemicals are linked with an ever increasing range of health conditions such as:

Cancers including liver, testicular, and pancreatic.
Cardiovascular disease
Kidney and liver damage
Premature birth
Immunosuppression and reduced vaccine response
Male infertility

Moving away from PFOS

In the early 2000s there was a moratorium on the use of PFOS. 3M, the main supplier, stopped manufacturing it. Many companies looked for alternatives. As a general rule, short chain PFAS compounds (that is compounds with fewer carbon atoms) are less stable and break down more readily. This led a lot of companies to start using PFHxS (perfluorohexane sulfate). Where PFOS has 8 carbon atoms, PFHxS has 6. The hope was that these compounds would accumulate less in the environment and in humans.

PFAS in human samples

Because of the concern about their health effects, the CDC began monitoring PFAS levels in the US population some 25 years ago. They chose to focus on the most widely used compounds. These included PFOS, PFOA, and PFHxS. As a result of this, we know a lot about how widespread exposure to these compounds actually is.

PFOS or its isomers occur in every sample tested by NHANES. In many cases, very high concentrations are detected. There is evidence that the overall levels are declining over the past few years. However, this is a slow process because PFOS is still so abundant in the environment.
PFOA is found in 100% of samples in the NHANES dataset. This is particularly concerning, since PFOA is a proven carcinogen according to the IARC. PFOA levels declined rapidly between 2000 and 2010, but the rate of decline has actually slowed
PFHxS appears in almost 99% of samples tested by NHANES. Some people in the NHANES study have extremely high levels. Detection levels of PFHxS seem to have peaked and are now declining reflecting the fact that it is no longer so widely used.

What does this mean in practice?

If you have had a PFAS blood test, there’s a very high chance that your result came back positive for these three compounds. Just having these compounds doesn’t necessarily mean you are at increased risk though. The best source of advice for that is the National Academies of Science, Engineering, and Medicine (NASEM). According to the NASEM guidelines for physicians, what matters is the overall sum of all the PFAS detected.

Our app shows you your predicted NASEM score and a summary of the guidance. If this is under 2 ng/mL then you needn’t worry. If it’s between 2 and 20 ng/mL then NASEM advises certain additional tests, especially for higher risk groups. Over 20 ng/mL is viewed as a high level and everyone should seek additional testing through their physician.

‍