High prenatal PFAS exposure linked to increased childhood asthma risk

Children exposed to very high levels of PFAS before birth face a significantly higher risk of developing asthma, according to new research from Lund University in Sweden.

The study analysed more than 11,000 children born in Blekinge county between 2006 and 2013, finding asthma risk was around 40 percent higher among children whose mothers had very high PFAS exposure during pregnancy compared with those with low exposure.

The children were followed from birth to the age of 12, with the analysis showing that 16 percent of children in the low-exposure group developed asthma, compared with 27 per cent among those with very high prenatal exposure.

But we saw a clear link between very high PFAS exposure and a higher incidence of asthma.

The risk of developing asthma was around 40 percent higher among children of mothers with very high PFAS exposure.”

 

Annelise Blomberg, researcher in occupational and environmental medicine at Lund University

However, the increased risk was only observed at the highest exposure levels. The study found no increased incidence of asthma among children whose mothers experienced intermediate PFAS exposure.

Contamination case in southern Sweden

The findings draw on a major contamination event in southern Sweden. In 2013, high PFAS levels were discovered in drinking water in Ronneby municipality after firefighting foam used during drills at the F17 military regiment polluted the water supply. Around one third of residents were exposed, with contamination believed to have been ongoing for more than 30 years.

PFAS – perfluoroalkyl and polyfluoroalkyl substances – are a large group of synthetic chemicals used in many industrial and consumer applications, including firefighting foam and certain food-related materials. These substances are highly persistent and can remain in the body for long periods. PFAS can also cross the placenta, meaning exposure during pregnancy can affect the developing foetus.

How PFAS exposure was assessed

To estimate prenatal exposure, the study analysed mothers’ residential addresses during the five years prior to the child’s birth, linking this information with municipal drinking water supply data.

Children were then grouped according to the level and duration of maternal exposure to PFAS-contaminated drinking water:

• Very high exposure: mothers lived at an address with heavily PFAS-contaminated drinking water for all five years prior to birth
• High exposure: mothers lived at such an address for at least one of the five years prior to birth
• Moderate exposure: mothers lived in Ronneby but not at an address with heavily contaminated drinking water
• Control group: mothers lived elsewhere in Blekinge county outside Ronneby

The study included 11,488 children, comprising 194 in the very high exposure group, 479 in the high exposure group, 1,591 in the moderate exposure group, and 9,224 in the control group.

We can only observe this link.

We cannot say for certain that the increase is specifically due to PFAS, but we have done our best to rule out other factors that might influence the results.”

 

Anna Saxne Jöud, associate professor of epidemiology at Lund University.

The analysis accounted for several factors that could influence asthma risk, including socio-economic status and smoking during pregnancy, ensuring comparisons were made between children with similar backgrounds.

This study differs from previous epidemiological investigations in that it includes participants with very high exposure to PFAS.

This provides a greater range of exposure than is usually observed in population-based studies.

This makes it possible to assess potential health effects at high PFAS concentrations, which is relevant for highly exposed populations worldwide.”

 

Annelise Blomberg and Anna Saxne Jöud, Lund University

Study limitations and future research

Several limitations were acknowledged. Exposure estimates were based on maternal residential addresses, meaning the study could not account for individual differences in drinking water consumption or changes in contamination levels over time. The research also could not separate exposure during foetal development from exposure in early childhood, as many children continued living at exposed addresses after birth.

Further investigation is needed to determine whether similar results occur in other populations with high PFAS exposure and whether the chemicals could affect lung function even at lower exposure levels.

We will also refine our exposure models for Ronneby in order to pinpoint the timing and intensity of PFAS exposure even more accurately.

This would improve our ability to analyse how exposure at different stages of development can affect children’s health.”

 

Annelise Blomberg, Lund University