Prenatal 'Forever Chemical' Exposure Linked to Childhood Leukemia in UC Irvine Study

Researchers at UC Irvine went looking in the blood of newborns and found 17 different PFAS, the man-made compounds known as "forever chemicals." The samples came from babies born in Los Angeles County between 2000 and 2015, and what the team found in them has been linked to the most common cancer in children.

The study compared two groups. One was 125 children who were later diagnosed with acute lymphoblastic leukemia. The other was 219 children who stayed cancer-free. That makes 344 newborns in all. The blood had been taken at birth, so the measurements reflect what the babies carried from the start, not what they picked up later in childhood. The findings appeared in April in the Journal of Exposure Science & Environmental Epidemiology.

Most of the chemicals detected were PFOA and PFOS. Elevated levels of them were associated with a greater likelihood of developing acute lymphoblastic leukemia, and when both were present together, the association with cancer risk was stronger still. PFAS is a catch-all label for roughly 14,000 compounds. They earned their nickname because they break down so slowly and can accumulate in the body. They turn up in drinking water, nonstick cookware, food and drink packaging, and cosmetics.

The authors do not claim these chemicals cause leukemia. The data suggest only that they may contribute to risk. Veronica Vieira, the study's corresponding author and a UCI professor of environmental and occupational health, said the work moves researchers closer to knowing what babies are exposed to from the very beginning, because it measures PFAS present at birth. Capturing exposure during a critical window of development, she said, gives a clearer picture of how contaminants may bear on childhood cancer risk.

Outside voices urged restraint. Rena Jones, a National Institutes of Health researcher who studies environmental contaminants and was not part of the study, said the findings should be interpreted cautiously, since the research covered only Los Angeles County and used a small sample. She also said it adds to growing evidence that PFAS exposure in pregnancy may contribute to this leukemia. The study notes that childhood cancer rates have risen in recent decades in industrialized countries, including the United States, which hints at environmental factors. The same team had earlier tied elevated PFOA and PFOS to other childhood cancers, including acute myeloid leukemia and Wilms tumor.

The data also showed a pattern in who carried more of the chemicals. Children with higher PFOS exposure tended to have older parents, to have been born in the U.S., and to have parents with more education and private insurance. Vieira explained that PFAS often appear in nonessential or pricier products, such as Scotchgard, weather-resistant clothing and makeup, so high levels can serve as an indirect measure of socioeconomic status.

There was some encouraging news. Children born later in the study period had lower PFAS levels, which Vieira said indicates that some of the more persistent chemicals have been phased out of production. "They're slowly degrading in the environment and being excreted," she said. She noted that drinking filtered water is one easy way to cut exposure further.

But the team also identified 26 additional PFAS, including compounds that have not been well studied, and Vieira said it is unclear how toxic they are. Jones said the results point to the need for larger studies covering a broader range of PFAS, newer compounds among them.