Study finds prenatal exposure to dozens more PFAS than previously detected in cord blood

Babies born between 2003 and 2006 were exposed in utero to a broader range of per- and polyfluoroalkyl substances (PFAS) than previously documented, according to a study published in Environmental Science & Technology.^1,2

Using a data science–based approach and advanced chemical detection methods, investigators identified dozens of PFAS in archived umbilical cord blood samples, including compounds not routinely measured in traditional testing panels.

The study, led by Shelley H. Liu, PhD, associate professor of population health science and policy at the Icahn School of Medicine at Mount Sinai, applied both targeted laboratory testing and PFAS-focused nontargeted analysis (NTA) to cord serum samples from the Health Outcomes and Measures of the Environment (HOME) Study, a prospective pregnancy and birth cohort based in Cincinnati, Ohio.

PFAS are a large class of synthetic chemicals used in products such as nonstick cookware, stain-resistant fabrics, food packaging, and firefighting foams. They are often referred to as “forever chemicals” because they persist in the environment and in human tissue.

Broader detection of PFAS in cord blood

Researchers analyzed archived umbilical cord blood samples collected between 2003 and 2006 from 120 infants. Targeted laboratory methods quantified 8 legacy PFAS compounds. In contrast, PFAS-focused NTA identified 42 confirmed or putatively identified PFAS in cord blood, including perfluorinated chemicals, polyfluorinated chemicals, and fluorotelomers.

The NTA approach uses high-resolution mass spectrometry to scan broadly for hundreds to thousands of chemical features rather than limiting detection to a predefined list. Of the 42 PFAS detected using NTA, only 4 overlapped with the compounds measured in targeted testing, underscoring the limitations of traditional panels.

To summarize cumulative exposure, investigators developed 2 metrics using item response theory: a “PFAS burden” score based on targeted concentrations and a “PFAS-omics” score derived from the relative abundance of PFAS detected by NTA.

The PFAS-omics score was designed to represent an infant’s overall prenatal PFAS exposure at a single point in time.

“Our findings suggest that how we measure PFAS really matters,” said Liu, first and co-corresponding author of the study. “When we look more comprehensively, we see that babies are exposed to far more PFAS chemicals before birth than we previously realized—and some of the patterns we thought we understood may change.”

Parity patterns differ by measurement method

Prior studies using limited PFAS panels have reported lower PFAS concentrations among multiparous compared with nulliparous mothers, suggesting that pregnancy and lactation may reduce maternal body burden of certain legacy compounds.

In the present study, targeted PFAS burden scores and concentrations of legacy compounds such as perfluorooctanoic acid and perfluorooctanesulfonic acid were significantly lower among infants born to primiparous and multiparous mothers compared with nulliparous mothers.

However, when investigators used the broader PFAS-omics score incorporating 42 PFAS identified through NTA, no significant differences were observed across parity groups.

“Our study helps show that prenatal PFAS exposure is more complex and widespread than earlier studies suggested,” Liu said. “Understanding the full picture is essential if we want to protect child health and reduce preventable environmental risks.”

Clinical and public health implications

Pregnancy represents a period of vulnerability to environmental exposures. Prior epidemiologic studies have linked prenatal PFAS exposure to low birth weight, preterm birth, altered immune responses to vaccines, metabolic changes, and other developmental outcomes. The American College of Obstetricians and Gynecologists has identified reducing exposure to toxic environmental chemicals, including PFAS, as a “critical area of intervention.”

PFAS exposure is not currently measured in routine clinical care. The authors suggest that cumulative exposure metrics such as PFAS-omics scores may, in the future, support the identification of individuals or populations with higher exposure burdens and inform preventive strategies.

“For now, this work helps lay the scientific foundation,” Liu said. “Our goal is to move toward earlier identification and prevention, especially during sensitive windows like pregnancy.”

The HOME Study cohort, which includes long-term follow-up into adolescence and young adulthood, offers the opportunity to evaluate whether higher cumulative PFAS exposure in early life is associated with subsequent health outcomes. Investigators also plan to further refine PFAS-omics tools and examine the potential effects of newer and understudied PFAS compounds detected in cord blood.

As regulatory and industrial landscapes evolve, the findings highlight the importance of comprehensive exposure assessment when evaluating environmental risks during pregnancy.

References

1. Babies are exposed to more “forever chemicals” before birth than previously known, new study finds. Mount Sinai. February 18, 2026. Accessed February 18, 2026. https://www.mountsinai.org/about/newsroom/2026/babies-are-exposed-to-more-forever-chemicals-before-birth-than-previously-known-new-study-finds
2. Liu SH, Chen Y, Feuerstahler L, et al. Quantifying PFAS-omics burden scores for nontargeted analysis using multidimensional item response theory: an exploratory analysis of novel and legacy PFAS in cord blood. Environ Sci Technol. Published online February 18, 2026. doi:10.1021/acs.est.5c06490