Levels of PFAS in mothers’ blood associated with children’s brain structure and functional outcomes

Researchers from the University of Turku and Turku University Hospital, Finland, and Örebro University, Sweden, found that levels of PFAS in mothers’ blood during pregnancy are associated with the structure and function of their children’s brains. The study is published in Lancet Planetary Health.

In recent years, researchers have discovered associations between levels of per- and polyfluoroalkyl substances (PFAS) in mothers’ blood during pregnancy and the neurodevelopmental outcomes of their children. A recent study led by the University of Turku, Finland, goes further by demonstrating that maternal PFAS predict structural and functional brain outcomes in their children.

PFAS are man-made chemicals used in the manufacturing of products that are resistant to water, oil, temperature, or electrical conductivity, such as cookware, clothing, furniture, food packaging, flooring, dental floss, and firefighting foams. Similar to plastics, they are not biodegradable and have been nicknamed “forever chemicals” for this reason. They are now found in all ecosystems on Earth and it is estimated that their presence in the soil will last more than 1,000 years.

“Humans consume PFAS from drinking water, food, or in some cases through occupational exposure. They are ubiquitous in our blood and our bodies do not break them down,” says Aaron Barron, lead researcher from the University of Turku and lead author of the study.

Over the past decade, increasing research has implicated blood levels of PFAS in adverse health effects, particularly hormone biosynthesis, metabolism, and immune system function. For this reason, PFAS have begun to attract considerable public, political, and academic interest and are now increasingly regulated in manufacturing and the water supply.

Different PFAS have been associated with different brain regions

The new study is part of the FinnBrain Birth Cohort Study, a longitudinal birth cohort established at the University of Turku in 2011.

Some mothers gave a blood sample during pregnancy and their blood levels of PFAS were measured by mass spectrometry at Örebro University in Sweden. Their children returned for a follow-up visit at age 5 and underwent multimodal magnetic resonance brain imaging at Turku University Hospital. The final analysis included 51 mother-child pairs.

Researchers found that maternal PFAS was linearly associated with many aspects of their children’s brain structure. The three main brain regions involved were the corpus callosum, the largest white matter tract in the brain; the surface area and volume of the posterior gray matter volume, in the occipital lobe; and the hypothalamus, which regulates homeostasis and endocrine function in our body. None of the associations were different in boys and girls.

Additionally, some PFAS were associated not only with brain structure but also with brain functional connectivity based on functional MRIs.

“We were able to measure seven different PFAS in this study and found that individual compounds had specific associations with the brain structure of the offspring and that in some cases two different PFAS had opposite relationships with the same brain region,” explains Professor Tuulia Hyötyläinen from Örebro University.

PFAS could be divided into two groups based on their chemical structure, whether they contain a carboxylic acid or sulfonic acid functional group. In most cases, with the exception of the hypothalamus, PFAS containing carboxylates were those most strongly associated with brain outcomes in children.

“At the moment, it is not known whether PFAS directly affect brain development, although it is known that they cross the placenta and the blood-brain barrier to accumulate in the brain and can disrupt brain cell development. It is also not known whether these associations are harmful, beneficial or neutral, and future studies will be needed to determine the functional implications of our results,” explains Professor Hasse Karlsson from the University of Turku.