The Next Frontier in PFAS Regulation: Measuring What Matters

Emerging research suggests the next generation of PFAS regulation may depend less on finding contamination than on determining whether today’s monitoring methods and risk assessments adequately protect the earliest - and most vulnerable - stages of life. Rather than focusing solely on contamination and cleanup, scientists are increasingly asking whether current monitoring systems can accurately measure increasingly small concentrations of PFAS and whether regulatory frameworks adequately account for prenatal and childhood exposure.

During the Biden administration, U.S. regulators responded to these questions and concerns by lowering the parts per million of PFAS allowed in drinking water, expanding monitoring requirements, and accelerating restrictions on certain PFAS compounds. More recently, the Trump EPA is currently proposing to weaken the federal PFAS drinking-water rule, but it is not proposing to raise the numerical limits for PFOA and PFOS, which remain at 4 parts per million. Additionally, public utilities have invested billions of dollars in treatment technologies, and manufacturers have worked to replace legacy PFAS with alternative chemistries.

Two recent studies suggest that the next chapter of PFAS regulation may revolve around a different challenge.

The first, published in Environmental Monitoring and Assessment in July 2026, examines the practical implementation of the U.S. Environmental Protection Agency’s new drinking water standards. It concluded that significant technical and operational barriers remain. According to the study's authors, the implementation of the nation’s most stringent PFAS drinking water standards are likely to be hampered by laboratory detection limits, inconsistent analytical capabilities, quality assurance challenges, and resource limitations among smaller public water systems. Even when regulatory limits are established, reliably measuring contaminants at parts-per-trillion concentrations is far from straightforward.

At the same time, in a study published in July 2026 in Clinical Gastroenterology and Hepatology, researchers at the Icahn School of Medicine at Mount Sinai provided evidence that prenatal and early-life PFAS exposure is associated with elevated biomarkers of intestinal inflammation years later in childhood. Importantly, the study does not demonstrate that PFAS cause inflammatory bowel disease, but it reinforces growing evidence that fetal development and early childhood represent uniquely sensitive periods during which relatively small exposures may have lasting biological consequences.

Taken together, these findings raise a broader regulatory question: If vulnerable life stages require greater protection, are today’s monitoring systems - and the risk assessments that underpin regulatory limits - sensitive enough to identify exposures that matter most?

Increasingly, scientists argue that the future of PFAS regulation will depend not only on stronger standards but also on better exposure science, more sophisticated biomonitoring, and risk-management approaches that explicitly account for developmental susceptibility. Meantime, emerging research is shifting the PFAS conversation beyond detection toward a more fundamental question: Are current risk assessment approaches adequately accounting for when people are exposed, which PFAS they’re exposed to, and how those chemicals interact?

Q&A: Rethinking PFAS Risk Assessment

In this Q&A with 3E, Dr. Neil Hunt, principal at Yordas Group by 3E, discusses why developmental timing, chemical diversity, and mixture toxicity are challenging long-held assumptions about chemical risk assessment. 3E recently acquired Yordas Group, a leading international provider of scientific consulting and regulatory content services across chemical management, product stewardship, sustainability, and regulatory compliance.

The following interview has been edited for length and clarity.

Recent research suggests that when exposure occurs may be just as important as how much exposure occurs. Why does the timing of exposure matter so much?

The question of when someone is exposed for developmental toxicity is even more nuanced than whether exposure occurred before or after conception. Different developmental adverse effects can be triggered at different stages of pregnancy. This means that some adverse effects can be triggered during the embryonic stage, before the mother is even aware of the pregnancy.

This concept has broader implications than PFAS alone. For example, it contributed to the now-debunked interpretation of World Health Organization advice that suggested women of child-bearing age should never drink alcohol. The underlying issue is that different developmental effects can occur during different stages of pregnancy, including very early stages before pregnancy is recognized.

The ubiquitous presence of PFAS in drinking water and food means it is not possible for the general population to completely avoid exposure. The persistent, bioaccumulative, and toxic (PBT) properties of PFAS add a further concern because intake before conception can still lead to exposure after conception from PFAS that has accumulated in the body.

For these reasons, placing strict limits on PFAS in drinking water seems to be a sensible precaution. However, doing so may place a significant burden on water companies that must implement remediation technologies. That also raises an important policy question: Should those costs ultimately be borne by water utilities and passed on to consumers through higher bills, or by the companies that have profited from placing these substances on the market, a subject referred to in the academic arena as “environmental justice”? These are the difficult questions that policymakers and governments will need to address in the near future.

PFAS are often discussed as though they are a single class of chemicals. Why is that an oversimplification from a toxicological perspective?

The term PFAS covers a huge range of individual substances that contain different functional groups. While they all contain carbon-fluorine bonds that are strongly linked to environmental persistence and bioaccumulation, it is not clear whether this structural feature is the only part of the molecule responsible for toxicity.

This means different PFAS are likely to trigger different adverse outcome pathways and to differing degrees. For example, PFAS containing sulfonate groups have been linked to greater activity with thyroid receptors than those containing carboxylic acid groups, although both of these polar groups are regarded as fundamental to the mechanism of toxicity because they enable the substances to bind to receptors.

Most regulatory testing of industrial chemicals used to identify endocrine disruptors is based on standardized methods such as Organization for Economic Cooperation and Development (OECD) Test Guideline 414, which observes effects on offspring at birth. Academic researchers may examine more closely the stage of pregnancy at which those adverse effects were triggered, but there are simply not enough researchers to examine every different PFAS in that level of detail.

Mixture toxicity is receiving increasing attention in PFAS research. Why does it present such a significant challenge for regulators and risk assessors?

The observation that toxicity arising from exposure to multiple substances at once - mixture toxicity - may be relevant to PFAS toxicity adds yet further complexity to the situation.

Different PFAS substances are used for different purposes, but once they are released into the environment, the general population will inevitably be exposed to several PFAS through drinking water, air, or food.

Assessing potential mixture effects is not thoroughly addressed within current regulations, largely because the fundamental science is still in its infancy. The standardized methods used to test the hazards of industrial chemicals do not explicitly state how they should be adapted to address mixtures. Regulations such as EU REACH (Regulation on the Registration, Evaluation, Authorization, and Restriction of Chemicals) also do not require hazard testing of mixtures.

That is unlikely to change in the short term because of the potentially enormous number of animal studies that would be required. Mixture hazard assessments are more likely to become viable once new approach methodologies (NAMs), including in vitro methods and predictive models, become sufficiently developed and accepted that risk assessors can have confidence in the results.

Until then, regulators may require more stringent safety factors when calculating safe human exposure levels from toxicology studies. Those safety factors will only be loosely based on scientific observation and will largely represent a precautionary approach.

What do these scientific uncertainties mean for the future of PFAS regulation?

As our understanding of developmental toxicity, chemical diversity, and mixture toxicity continues to evolve, risk assessment will inevitably become more complex. The challenge for regulators is balancing emerging scientific evidence with practical decision-making.

Where the science remains uncertain, regulators may increasingly rely on precautionary safety factors while NAMs continue to mature. Over time, more sophisticated in vitro methods and predictive models should provide greater confidence in assessing the hazards of PFAS mixtures and help refine future regulatory decisions.

This is Part 1 of a four-part series. Read the other articles in the series: PFAS: Detection Is Becoming the New Bottleneck (Part 2), PFAS: Thinking Beyond the Dose (Part 3), and Looking Beyond Individual Chemicals: Why PFAS Risk Assessment Is Evolving (Part 4).