What is PFAS biomonitoring?

Sometimes known as Human Biomonitoring, or HBM, biomonitoring is the measurement of the concentration of chemicals or their metabolites in human biological samples – such as blood, urine, milk, hair, nails, and meconium. Today, according to the NGO Health and Environmental Alliance (HEAL), biomonitoring is the global “standard procedure for assessing people’s exposure to chemicals that may be harmful to health, and responding to environmental public health issues.” The advantage of working with human biological samples - rather than more traditional environmental matrices, such as air, water and food - is that “the data reflect actual rather than estimated chemical exposures,” which derive from all exposure routes and pathways. They can thus give us an accurate picture of both an individual’s chemical “body burden” and – if the data obtained are representative of a general population - the wider prevalence and extent of exposure to chemicals.

Why is biomonitoring PFAS important?

In February, the UK government described Per- and perfluoroalkylated substances (PFAS) as “one of the most pressing chemical challenges of our time.” PFAS are a class of between 10 -15,000 chemicals whose unique non-stick and grease/water repellent properties have made them key components in everyday goods since the 1940s. But the enormously strong carbon-fluorine bonds that make them useful in non-stick pans, food contact materials, textiles, and firefighting foams also enable them to resist degradation indefinitely. Once present in the environment, they bioaccumulate in water, plants, wildlife, and people all around the globe – earning them the pejorative nickname of “forever chemicals”.

A number of PFAS have also been linked to the development of serious illnesses – including testicular and kidney cancer, ulcerative colitis, thyroid disease, high cholesterol, pregnancy-induced hypertension, suppression of antibody response, liver damage, plus developmental and reproductive toxicity. The risk of becoming ill from PFAS exposure is often far greater for those working in, or living near, industrial facilities involved in PFAS manufacturing or processing.

However, the ubiquity and long half-lives of “forever chemicals” means that everyone needs to be concerned about PFAS exposure – not just those who live near a major PFAS source. A US National Health and Nutrition Examination Survey (NHANES) survey published last year showed that over 96% of 12-19 year-olds tested had measurable concentrations of four legacy PFAS in their blood – even though some were born after the chemicals were banned, restricted, or phased out. Meanwhile, an average of 14.3% of teenagers tested in Europe had blood levels above the recommended health-based guidance value. A separate testing programme also found that blood samples taken from 24 senior European Union leaders were all contaminated with PFAS, half of them at levels “beyond which health impacts cannot be ruled out.”

Biomonitoring and PFAS regulation

Increasing concerns about their health and environmental effects have pushed PFAS chemicals to the top of the news agenda, and prompted politicians to take action in many parts of the world. While there is evidence that the Trump administration may be “watering down” PFAS regulations introduced previously in America, more than a dozen US states have introduced their own legislation on forever chemicals, and Canada is looking at wide-reaching plans to regulate PFAS as a class. In Europe, those same EU ministers with PFAS in their blood may soon be voting on plans for a near-total ban on PFAS, while France and Denmark have already introduced their own partial restrictions. As more and more countries consider their own responses, PFAS biomonitoring data can help shape new and better regulation aimed at minimising forever chemicals’ health and environmental effects.

How biomonitoring works

Biomonitoring of human exposure to environmental chemicals is carried out through the analysis of biomarkers. A biomarker can be the chemical substance itself, its metabolite(s), or the products of interaction between the chemical and target biomolecules. Furthermore, scientists divide biomarkers into three main categories, each of which plays a different role in assessing the impact of chemicals on the body.

The three main types of biomarker are:

• exposure biomarkers – which assess the presence of an exogenous chemical from interactions between chemicals/toxins and target molecules/cells in biological samples
• susceptibility biomarkers – which indicate the genetic predisposition of an individual organism to respond to exposure to chemicals or toxins, and
• biomarkers of effect (aka biological response biomarkers). These are observable and measurable changes in an organism's biochemical, molecular, cellular, or functional components resulting from exposure to chemical contaminants.

Biomarkers of effect related to PFAS exposure include elevated concentrations of lipids and enzymes in serum samples, which can be indicators of liver toxicity.

What PFAS biomonitoring is used for

As well as helping clinical toxicologists to assess patients’ exposure to forever chemicals and to provide appropriate care, PFAS biomonitoring has become increasingly relevant in supporting wider research, healthcare, legal, and regulatory activities around the world. For example, it can help in identifying new exposures and in conducting epidemiological studies, as well as establishing the extent of PFAS exposure among the general population and in vulnerable groups.

In addition, PFAS biomonitoring plays a key role in legal and workplace investigations - such as when Sweden’s Supreme Court ruled in 2024 that high levels of PFAS in blood were alone enough to prove that Ronneby residents had suffered personal injury from their contaminated water. And last year, evidence of high PFAS levels in the blood of residents living near the Miteni fluorochemicals plant in Veneto, Italy, was a key part of a groundbreaking chemical pollution case that resulted in the jailing of 11 executives.

Analytical challenges in PFAS biomonitoring

The most popular technique for determining known PFAS in human samples is Liquid Chromatography - Tandem Mass Spectrometry (LC-MS/MS). However, there have also been some efforts to use Gas Chromatography - Mass Spectrometry (GC-MS) and High Resolution Mass Spectrometry (HRMS) for analysing volatile PFAS and for identifying new compounds.

When using LC-MS/MS, ultrashort chain PFAS pose challenges due to their small size and high polarity, while matrix effects such as ion suppression or enhancement can significantly impact method accuracy, precision and sensitivity. In response, researchers have employed isotope labelled internal standards and matrix-matched calibration in order to obtain robust results.

However, measuring levels of PFAS in human biological samples remains challenging overall because of the huge numbers of PFAS compounds that already exist, and the emergence of new chemicals to replace so-called “legacy” compounds. As HEAL points out, “methods for detecting PFAS in blood have only been developed for a very small number of the thousands of PFAS people are exposed to. Thus overall PFAS exposure is always underestimated.”

The importance of PFAS-free blank matrices

Another significant challenge in biomonitoring PFAS is the difficulty of obtaining human blank matrices that are truly free of contamination, such is the ubiquity of forever chemicals in humans and the environment. Animal-derived matrices, such as charcoal-stripped fetal bovine serum and artificial plasma, may be viable alternatives. However, bovine serum blanks may also contain low levels of PFAS contamination that could result in higher detection limits for those compounds. It is therefore advisable for analytical scientists to evaluate and remove any other potential sources of PFAS contamination that may exist in their laboratories, in order to enhance overall quantification accuracy. Ways of minimising such contamination include avoiding polytetrafluoroethylene-containing lab equipment like gloves, containers, and tubes, as well as installing a delay column between pump and injection in LC instruments.

Alternative matrices for PFAS biomonitoring

Blood is an ideal biomonitoring matrix for most chemicals, since “blood plasma is in contact with every tissue in the body and is in steady state with all organs.” However, its main disadvantage is that it is invasive, which means that it needs to be collected by medically qualified personnel. This last factor in particular could make other blood collection techniques – such as dried blood spots and volumetric absorptive microsampling (VAMS) devices – attractive in some scenarios. At the same time, matrices such as hair, nails and urine can also provide us with useful and reliable samples for biomonitoring, and potentially yield alternative insights into human PFAS exposure.

One review paper argues that the combining analysis of hair and nails could give researchers “a more comprehensive understanding of internal PFAS exposure.” This is because nails tend to provide higher detection frequencies and concentrations for perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) compared to hair. Meanwhile, hair seems to be more sensitive to compounds like perfluorohexane sulfonic acid (PFHxS). Urine is also useful as a non-invasive biomonitoring matrix for exposure to short-chain PFAS, but its limited utility in detecting longer-chain compounds means that complementary matrices are also needed.

Last but not least, synthetic matrices can also offer a practical and scalable alternative for biomonitoring laboratories - by closely mimicking the chemical composition and physical properties of human biological samples, but without duplicating their limitations. In particular, they provide a reliable foundation for method development, validation, and instrument calibration.

Andy Blizzard

Content Writer

Andy Blizzard joined LGC Standards in 2021. An NCTJ-qualified journalist with over 15 years' experience, he specialises in translating complex technical data into accessible insights for the life sciences sector.