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Harmful substances

Researchers find link between PFAS and children's IQ

A new study from the University of Southern Denmark (SDU) and Odense Child Cohort shows a correlation between exposure to PFAS as a fetus and lower intelligence quotient (IQ) at the age of 7.

Per- and polyfluoroalkyl substances (PFAS) have been suspected as harmful to health for decades. PFAS are transferred through the placenta and breast milk to fetuses and newborns, which is significant as they are still in development and thus more vulnerable.

The brain, in particular, is sensitive due to its rapid growth and complexity.

Researchers from the University of Southern Denmark (SDU) have investigated whether there is a link between exposure to PFAS in the unborn child and infant and subsequent cognitive development at the age of 7.

Based on data from children in the Odense Child Cohort, the study is part of a Ph.D. project conducted by Iben Have Beck at the Department of Clinical Pharmacy, Pharmacology and Environmental Medicine at SDU.

PFAS from mothers to fetuses

The study, published in the scientific journal American Journal of Epidemiology, shows that high concentrations of PFAS measured in mothers’ blood during pregnancy were associated with slightly lower IQ scores among their children at the age of 7.

- Our results are concerning and support the suspicion that fetal exposure to PFAS could be detrimental to brain development. However, it’s important to emphasize that we only found modest drops in IQ, and thus our findings probably don’t have significant implications for individual children, explains Iben Have Beck and elaborates:

- On the other hand, even small drops in IQ across an entire population can lead to significant societal consequences, given that everyone is exposed to PFAS.

Our findings probably don’t have significant implications for individual children. On the other hand, even small drops in IQ across an entire population can lead to significant societal consequences

Iben Have Beck, postdoc

A total of 967 pregnant women and their children participated in the study, where five different types of PFAS were measured in blood samples from both mothers and children at 18 months of age.
Each child’s IQ was assessed at the age of 7 by a psychologist at the child’s school using a shortened version of the Wechsler Intelligence Scale for Children version 5 (WISC-V).

Breastfeeding could play a role

The study failed to determine whether the child’s own exposure to PFAS had an impact on future cognitive development.
No connection was found between the child’s PFAS concentrations in the blood at 18 months of age and subsequent IQ at the age of 7.

However, the results were difficult to interpret because it wasn’t possible to separate the beneficial effects of breastfeeding from potentially harmful effects of PFAS exposure.

- In the initial analyses, we unexpectedly found that the higher the child’s PFAS concentrations in the blood at 18 months of age, the higher their IQ was at the age of 7. However, this relationship disappeared when we accounted for the well-known beneficial effects of breastfeeding in more advanced statistical models, says Iben Have Beck.

Multiple measurements provide new insights

She explains that this is likely due to the fact that the child is primarily exposed to PFAS through breast milk.

- It’s well-known that breastfeeding is important and beneficial for children’s cognitive development, partly attributed to the transfer of essential fats and nutrients, as well as the sense of security and attachment that develops during breastfeeding.

The researchers were only able to account for the number of months children were breastfed but not the quantity or frequency of breastfeeding. As a result, they were unable to separate the well-established beneficial effects of breastfeeding on IQ from the potentially harmful effects caused by PFAS exposure.

More about PFAS

  • Perfluoroalkyl og Perfluoroalkyl substances (PFAS) are a group of chemically synthesized compounds with water- and grease-repellent properties. PFAS are used, among other things, for waterproofing and surface treatment of furniture, clothing, footwear, kitchen utensils, and in firefighting foams. 

  • These substances have a strong chemical structure that makes them resistant to degradation. Their long half-life leads to their accumulation in our bodies and in the environment when PFAS are released from products during use or when PFAS-treated products are discarded. Humans are primarily exposed to PFAS when we consume PFAS-contaminated food and drink.
  • The use of PFAS has been subject to ongoing regulation. For example, PFOS, PFOA, and now PFHxS are globally regulated through the UN's environmental program "The Stockholm Convention," and the EU has recently lowered the permissible levels for 4 PFAS (PFOS, PFOA, PFHxS, and PFNA) in drinking water. In Denmark, the use of PFAS in food packaging made of paper and cardboard was prohibited in 2020.
  • Despite these measures, new and old PFAS compounds can still be detected in the blood of virtually all individuals. PFAS spread and accumulate in the environment, leading to continuous exposure through secondary pathways.

- It will hopefully be possible in future analyses, as we are currently measuring the child’s PFAS at the age of 5, allowing us to investigate whether the child’s own exposure to PFAS has an impact on future cognitive development, Iben Have Beck concludes.

The study was conducted in collaboration between the environmental medical research group at the Department of Clinical Pharmacy, Pharmacology, and Environmental Medicine, the research unit for Child and Adolescent Psychiatry at SDU, Odense Child Cohort, Odense University Hospital (OUH), and Odense Municipality.

Read the scientific article in American Journal of Epidemiology

About the Odense Child Cohort

  • The study was conducted by the Odense Child Cohort, which follows 2,550 families from Odense starting from pregnancy until the child reaches 18 years of age. The purpose is to gain new insights into children’s health and well-being and, in collaboration with entities like Odense Municipality, translate this knowledge into concrete action plans for health promotion and prevention. 

  • The project is financially supported by Odense University Hospital, Odense Municipality, and the Psychiatry Department in the Region of Southern Denmark, and it continues until the year 2030. Learn more about the Odense Child Cohort here 
Meet the researcher

Iben Have Beck is a postdoc at the Department of Public Health in the research unit of Clinical Pharmacy, Pharmacology and Environmental Medicine. She has completed a Ph.D. on the effects of PFAS exposure on fetuses and infants and development in childhood.



Marianne Lie Becker, journalist, Faculty of Health Sciences, phone 65 50 28 88, mobile 21 26 19 26, e-mail

Editing was completed: 14.08.2023