Babies exposed to far more “forever chemicals” before birth than scientists knew

These substances, known as per- and polyfluoroalkyl substances or PFAS, include thousands of compounds that are still widely used. Scientists do not yet fully understand their effects on human health, which makes it especially important to measure how much exposure happens before birth.

The research was led by Shelley H. Liu, PhD, Associate Professor of Population Health Science and Policy at the Icahn School of Medicine at Mount Sinai. Her team is the first to apply a data science-based method to estimate a newborn's overall PFAS exposure using advanced chemical analysis of umbilical cord blood.

PFAS are synthetic chemicals found in products such as nonstick cookware, stain resistant fabrics, food packaging, and firefighting foams. They are often referred to as "forever chemicals" because they break down very slowly and can accumulate in the environment and in the human body.

Umbilical Cord Blood Reveals 42 PFAS Compounds

To better understand prenatal exposure, the researchers analyzed stored umbilical cord blood samples from 120 babies who participated in the Cincinnati based HOME Study. The samples were originally collected between 2003 and 2006. Because the children are now adolescents, the team can eventually examine how early PFAS exposure may relate to later health outcomes.

Instead of testing for only a small list of known chemicals, the scientists used a non-targeted chemical analysis method -- a technique that scans for hundreds to thousands of chemicals at the same time rather than testing for a short, predefined list. This broader approach revealed many more PFAS in cord blood than traditional testing typically detects, including newer and less studied compounds.

In total, the team identified 42 confirmed or putatively identified PFAS chemicals in the cord blood samples. Many of these substances are not included in routine testing panels, and their health effects remain unclear. The findings show that babies are exposed before birth to a diverse mix of PFAS, including perfluorinated chemicals, polyfluorinated chemicals, and fluorotelomers.

New PFAS-Omics Burden Scores

To summarize overall exposure, the researchers developed PFAS-omics burden scores using item response theory methods. These scores provide a snapshot of a newborn's total PFAS exposure at a given point in time.

When the scientists applied this more comprehensive measurement, they did not find differences in exposure between babies born to first time mothers and those born to mothers who had previous pregnancies. Earlier studies that relied on narrower PFAS panels had reported such differences.

"Our findings suggest that how we measure PFAS really matters," said Dr. Liu, first and co-corresponding author of this 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."

Why Prenatal PFAS Exposure Matters

Pregnancy is a sensitive window of development. Previous research has linked prenatal PFAS exposure to low birth weight, preterm birth, changes in immune response to vaccines, metabolic shifts, and other developmental concerns.

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

The American College of Obstetricians and Gynecologists has identified reducing exposure to environmental toxins such as PFAS as a "critical area of intervention."

Implications for Clinical Care and Prevention

At present, PFAS exposure is not routinely measured in clinical settings, even though growing evidence suggests these chemicals can influence multiple aspects of health.

The new approach offers a way to estimate cumulative PFAS exposure more fully. In the future, tools like this could help clinicians:

• Identify individuals with higher exposure burdens
• Monitor at risk populations more closely
• Inform preventive medicine strategies

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

Next Steps in PFAS Research

The research team plans to examine whether higher cumulative PFAS exposure in early life is associated with negative health outcomes. They also aim to study the potential health effects of newly identified and understudied PFAS found in cord blood, and to continue refining tools that support primary disease prevention.

Funding: National Institutes of Health

Collaborating Institutions: University of Michigan, Fordham University, Brown University, University of Cincinnati, University of Pennsylvania, Yale University, Simon Fraser University