Babies are Exposed to Far More “Forever Chemicals” Before Birth than Scientists Previously Knew

Babies born between 2003 and 2006 were exposed to far more “forever chemicals” in the womb than researchers had previously thought, according to a study published in Environmental Science & Technology.

What are PFAS?

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 is why it is particularly important to measure prenatal exposure levels.

The study was led by Shelley H. Liu, PhD, associate professor of population health sciences and policy at the Icahn School of Medicine at Mount Sinai. Her team is the first to use a data science method to estimate a newborn’s total 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 degrade 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 HOME study in Cincinnati. The samples were originally collected between 2003 and 2006. Now that the children are adolescents, the team can study how early PFAS exposure may affect later health.

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

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

New PFAS Omics Exposure Scores

To summarize overall exposure, the researchers developed PFAS omics exposure 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 method, they found no differences in exposure between babies born to first-time mothers and babies born to mothers who had been pregnant before. Previous studies based on narrower PFAS panels had found such differences.

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

Why Prenatal PFAS Exposure Matters

Pregnancy is a sensitive developmental period. Previous research has linked prenatal PFAS exposure to low birth weight, premature birth, changes in immune response to vaccines, metabolic changes, and other developmental problems.

“Our study helps to show that prenatal PFAS exposure is more complex and widespread than previous studies suggested,” Dr. Liu said. “It’s important to understand the big picture if we want to protect children’s 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

Currently, PFAS exposure is not routinely measured in clinical settings, even though there is growing evidence that these chemicals may affect various aspects of health.

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

• Identify individuals with higher exposure burdens
• Monitor at-risk groups more closely
• Develop preventive medicine strategies

“For now, this work helps lay the scientific groundwork,” said Dr. Liu. “Our goal is to achieve earlier detection and prevention, especially during sensitive periods such as pregnancy.”

Next Steps in PFAS Research

The research team plans to investigate whether higher cumulative PFAS exposure at a young age is associated with negative health outcomes. They also want to investigate the potential health effects of newly identified and understudied PFAS in umbilical cord blood and further refine tools to support primary disease prevention.