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

The blood samples were drawn when the children were only days old. Researchers at UC Irvine went back to those newborn samples, collected from babies born in Los Angeles County between 2000 and 2015, to ask what chemicals were already in their bodies at birth, and whether that might tell them something about the cancer some of them developed later.

The study compared two groups: 125 children who were later diagnosed with acute lymphoblastic leukemia, the most common childhood cancer, and 219 children who stayed cancer-free. Seventeen different PFAS, the group of compounds known as "forever chemicals," turned up in the samples, mostly PFOA and PFOS. Higher levels were associated with a greater likelihood of developing the leukemia, and when both PFOA and PFOS were present together, the association with cancer risk was stronger still. The work was published in April in the Journal of Exposure Science & Environmental Epidemiology.

The researchers are careful about what this does and does not show. They cannot say that forever chemicals cause cancer, only that the chemicals may contribute to risk. PFAS is a catch-all label for roughly 14,000 man-made compounds, tied in other research to cancers and fertility problems. They earned the 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.

"This research moves us closer to understanding what babies are exposed to from the very start by directly measuring PFAS present at birth," said Veronica Vieira, the study's corresponding author and a UCI professor of environmental and occupational health. She said that capturing exposure during a critical window of development gives a clearer picture of how environmental contaminants may feed into childhood cancer risk.

Outside experts see the results as meaningful but limited. Rena Jones, a National Institutes of Health researcher who studies environmental contaminants and was not involved, said the findings should be interpreted cautiously because the study covered only Los Angeles County and used a small sample. Still, she said, it adds to growing evidence that PFAS exposure during pregnancy may contribute to this leukemia. Childhood cancer rates have risen in recent decades in industrialized countries, including the United States, which the study says hints at environmental factors. The same team previously linked elevated PFOA and PFOS to other childhood cancers, including acute myeloid leukemia and Wilms tumor.

The data also showed who tended to carry more of these chemicals. Children whose parents were older, born in the U.S., more highly educated and covered by private insurance had higher PFOS exposure. Vieira explained that forever chemicals are common 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 suggests that some of the more persistent compounds have been phased out of production. "They're slowly degrading in the environment and being excreted," Vieira said. She noted that drinking filtered water is one easy way to cut exposure further.

The researchers also found 26 additional PFAS beyond the 17 most prominent ones, including compounds that have not been well studied. Vieira said it is unclear how toxic they are. Jones said the findings point to a need for larger studies covering a broader range of PFAS, newer compounds among them.