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

The blood came from heel pricks on newborns, drawn in Los Angeles County hospitals between 2000 and 2015. Years later, researchers at UC Irvine went back to those samples and found, in each of them, traces of the industrial compounds known as PFAS. In all, they detected 17 different ones.

The study, published in April in the Journal of Exposure Science & Environmental Epidemiology, compared two groups. One was 125 children who were later diagnosed with acute lymphoblastic leukemia, the most common childhood cancer. The other was 219 children who stayed cancer-free. Because the chemicals were measured in blood taken at birth, the team was looking at what the babies carried from the very start rather than relying on later recollections of exposure.

The compounds that turned up most were PFOA and PFOS. Higher levels were linked to a greater likelihood of developing the leukemia, and when both were present together, the association with cancer risk was stronger still.

PFAS is shorthand for a family of roughly 14,000 man-made compounds, often called forever chemicals because they break down slowly and can accumulate in the body. They show up in drinking water, nonstick cookware, food and drink packaging, and cosmetics. They have been tied to cancers and fertility problems.

The researchers are careful about what the results do and do not show. They cannot say the chemicals cause leukemia; the finding is 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 scientists closer to understanding what babies are exposed to by measuring PFAS present at birth. Capturing 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 because the work was confined to Los Angeles County and the sample was small. Still, she said, it adds to growing evidence that PFAS exposure in pregnancy may contribute to acute lymphoblastic leukemia. Childhood cancer rates have risen in recent decades in industrialized countries including the U.S., which the study says 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 who tended to carry more. 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 these chemicals turn up often in nonessential or pricier goods, such as Scotchgard, weather-resistant clothing and makeup, so high levels can serve as an indirect measure of socioeconomic status.

There was encouraging news as well. Children born later in the period had lower PFAS levels, which suggests that some of the more persistent compounds have been phased out of production. Vieira said they are slowly degrading in the environment and being excreted, and she noted that drinking filtered water is one simple way to cut exposure further.

But the researchers also identified 26 additional PFAS chemicals, some of them poorly studied, and Vieira said it is unclear how toxic they are. Jones said the findings point to the need for larger studies covering a broader range of PFAS, including newer compounds.