PFAS: Detection Is Becoming the New Bottleneck

The U.S. EPA’s drinking water standards for six PFAS compounds represent some of the strictest contaminant limits ever established under the Safe Drinking Water Act. From a public health perspective, the rationale is straightforward: If adverse health effects may occur at very low concentrations, regulatory standards should reflect the latest toxicological evidence.

Implementing those standards, however, is considerably more complicated than writing them. For example, in a paper published in the July 2026 edition of Environmental Monitoring and Assessment, researchers shared these findings:

• Approximately 38% of water samples collected between 2013 and 2016 had minimum reporting levels above today’s maximum contaminant levels (MCLs), limiting their usefulness for regulatory compliance.
• The authors concluded that many PFAS exceedances likely remain undetected because of low sample quality and infrequent monitoring.
• Larger public water systems experienced higher exceedance rates, likely reflecting more complex water systems and greater urban contamination.

Measuring PFAS Concentrations

Experts argue that monitoring capability has become one of the greatest implementation challenges for increasingly stringent PFAS regulations. Measuring PFAS at concentrations of just a few parts per trillion requires highly specialized analytical methods, rigorous quality assurance protocols, and laboratories capable of consistently achieving extremely low detection limits. Even seemingly minor contamination introduced during sampling or laboratory analysis can affect results.

The question of whether analytical uncertainty is becoming a regulatory issue in itself as standards become increasingly stringent is one that only the U.S. Environmental Protection Agency (EPA) can answer, but Lior Singer, the lead author of the study in Environmental Monitoring and Assessment and a PhD student at the University of Nevada, Reno, told 3E that based on past experience, “EPA usually issues new regulations only after an analytical method has been approved.”

As he pointed out, “Our paper discusses one challenge that can arise during this process. Samples analyzed before approval of a new method might not be suitable for comparison to newer results or for regulatory use. This can affect the interpretation of historical monitoring data and create challenges during regulatory review.”

Public water systems do not all begin from the same position. Larger utilities may have greater financial resources, established laboratory partnerships, and technical expertise to implement sophisticated monitoring programs. Smaller and rural systems, by contrast, may face significant logistical and financial hurdles in meeting new analytical requirements.

As regulatory thresholds decline, sampling procedures, instrument calibration, laboratory accreditation, method validation, and quality-control practices become increasingly important. Analytical variability that once had little practical significance may determine whether a water system is considered compliant. If monitoring methods cannot consistently distinguish between true contamination and analytical uncertainty at extremely low concentrations, regulators, laboratories, and utilities may face difficult questions about data interpretation, enforcement, and public confidence.

The Science Is Moving Earlier in Life

At first glance, measuring PFAS in drinking water and studying prenatal exposure appear to be separate scientific questions. In reality, they are closely connected. If research increasingly points to sensitive developmental windows, accurately detecting very small exposures becomes far more than a technical challenge: it becomes central to protecting public health.

As analytical scientists focus on detecting PFAS in the environment, health researchers are asking a different question: When do exposures matter most?

“During fetal development and early infancy, physiological processes, including the immune system and the gut microbiome, undergo rapid orchestration,” noted Malek. Even a low-dose exposure to PFAS during these windows could disrupt cellular programming, leading to latent health issues. Detrimental effects, such as persistent intestinal inflammation, may not manifest till later years.”

Uniquely Vulnerable Periods for Exposure

A Mount Sinai study published in the July 2026 issue of Clinical Gastroenterology and Hepatology adds to a growing body of research suggesting that prenatal development and early childhood may represent uniquely vulnerable periods for PFAS exposure. Rather than examining adult health outcomes, researchers evaluated PFAS exposure beginning during pregnancy and assessed markers of intestinal inflammation in children years later.

The study measured multiple PFAS compounds in maternal blood, umbilical cord blood, and newborn blood samples before following participating children over time. Researchers observed associations between higher prenatal exposure to PFAS mixtures and elevated levels of fecal calprotectin, a biomarker commonly used to identify intestinal inflammation.

Lead study author Dr. Manasi Agrawal, an assistant professor of medicine (gastroenterology) and environmental medicine and public health at the Icahn School of Medicine at Mount Sinai, told 3E that although genetics play an important role in inflammatory bowel disease, they do not fully explain why the disease develops.

“We measured PFAS levels in maternal plasma during pregnancy, cord blood, which represents both maternal and fetal circulation, and newborn blood spots, which represent neonatal exposure. Years later, we found evidence of intestinal inflammation based on elevated levels of fecal calprotectin in stool samples from these children.”

These findings tell us two things, she said: “First, mothers and babies are exposed to these chemicals during a very susceptible period, and those chemicals are biologically internalized. Second, it appears that these early-life exposures are associated with intestinal inflammation much later in childhood; up to four, five, six years of age, and in one cohort between nine and eleven years of age.”

Importantly, the study does not conclude that PFAS cause inflammatory bowel disease or other gastrointestinal disorders. Nor does it establish a direct causal relationship between PFAS exposure and later disease. Instead, it suggests that early-life exposure may influence biological processes that warrant additional investigation.

That distinction matters. Environmental health research increasingly focuses not only on disease outcomes but also on biological changes that may occur long before clinical illness develops. Biomarkers such as inflammatory proteins, immune responses, and metabolic indicators can provide early evidence that environmental exposures are affecting physiological systems even when symptoms are absent.

For PFAS researchers, these findings reinforce an important concept that has emerged across environmental toxicology: timing of exposure may be just as important as the amount of exposure.

“Monitoring these children for decades is challenging, but it’s necessary,” insisted Agrawal. “This is one piece of the puzzle, and we have to be careful not to overinterpret its clinical implications until we have more evidence.”

This is Part 2 of a four-part series. Read the other articles in the series: The Next Frontier in PFAS Regulation: Measuring What Matters (Part 1), PFAS: Thinking Beyond the Dose (Part 3), and Looking Beyond Individual Chemicals: Why PFAS Risk Assessment Is Evolving (Part 4).