Newborn blood samples reveal a concerning connection between industrial "forever chemicals" and the development of childhood cancer.

Axar.az reports, a few drops of blood drawn from a baby’s heel just hours after birth can give researchers a rare look at chemical exposures present at birth.

A new study published in the Journal of Exposure Science & Environmental Epidemiology used exactly that to examine a possible connection to one of the most common childhood cancers. Researchers analyzed dried blood spots collected from newborns in Los Angeles County and found that babies with the highest levels of certain PFAS—often called “forever chemicals” because they persist for years in the environment and the body—had increased odds of developing childhood leukemia.

PFAS chemicals are nearly inescapable in modern life and linger in the human body for years. PFAS are a large family of industrial chemicals found in nonstick cookware, waterproof clothing, fast-food packaging, and firefighting foam. Previous research cited in the study found PFAS in the blood of 98% of Americans. Even though major manufacturers began phasing out the most widely studied compounds in the early 2000s, these chemicals persist in the environment and in human bodies for years. Because they cross the placenta, babies are often born with these substances already circulating in their systems.

California's newborn screening program acted as a chemical time capsule for researchers. In California and most other states, a few drops of blood are collected from nearly every newborn, typically within 36 hours of birth, and stored on paper cards. Those cards become a snapshot of what was circulating in a baby’s blood at the moment of birth. Researchers tapped into a statewide registry linking childhood cancer cases to these stored cards, identifying 125 children diagnosed with acute lymphoblastic leukemia (ALL) in LA County between 2000 and 2015. They compared them to 219 cancer-free controls from the same area, with lab analysts kept "blind" to which samples came from cancer patients to ensure unbiased results.

Higher concentrations of "legacy" chemicals were associated with a significant rise in leukemia risk. Of 23 PFAS chemicals targeted in the analysis, 17 turned up in the blood spot samples. The two most common, PFOA and PFOS, were found in more than half of the newborns. The study found that children in the highest quarter of PFOS exposure had a 56% greater chance of developing leukemia compared to those in the lowest quarter. For PFOA, the increase in risk was 64%. While childhood leukemia remains rare—affecting roughly 3 to 5 children per 100,000 annually—researchers noted that the risk was highest among children who had elevated levels of both compounds simultaneously.

Modern replacement chemicals showed even stronger links to cancer than the older versions they replaced. Using a new detection method that works like a "chemical dragnet" to scan for any fluorinated substance, researchers found 26 additional PFAS in the newborn blood. Two of these stood out—both are chemicals used as modern replacements for older, phased-out versions. A doubling in exposure to one replacement was associated with a fivefold increase in leukemia risk. Another replacement saw children in the highest exposure group face more than five times the odds of developing leukemia compared to those in the lowest quarter. Though these estimates came from smaller subsets of samples, they represent a critical signal for scientists to investigate these newer compounds more closely.

Experts call for faster safety evaluations of newer chemicals entering the marketplace. While no single study of this size can establish absolute cause and effect, the findings add to a growing body of evidence. Other studies in California and Finland have pointed in a similar direction, linking PFAS exposure to childhood health risks. When a baby’s first drops of blood contain dozens of industrial chemicals, including compounds brought in as "safer" replacements for ones already flagged as harmful, it raises urgent questions about whether current regulations are keeping pace with chemical manufacturing.