PFAS has been linked to asthma in a small Swedish town, but are the findings relevant here?
By Rachel McDonald, the Australian Science Media Centre
In a Swedish town which experienced one of the worst incidences of PFAS contamination the world has ever seen, international researchers have linked exposure to the chemicals in pregnancy with a higher risk of children developing childhood asthma.
The municipality of Ronneby in Sweden's Blekinge County experienced high levels of contamination from per- and polyfluoroalkyl substances (PFAS) in drinking water from chemicals found in firefighting foam used at a nearby military base until the contamination was discovered in 2013.
To investigate how this may have impacted children whose mothers were exposed during pregnancy, Swedish researchers studied data from 11,488 children born in the wider Blekinge County between 2006 and 2013, following up until 2022. The researchers used the mothers' addresses to estimate their level of PFAS exposure, and found those who likely had exceptionally high levels of exposure were more likely to have children who went on to develop asthma.
Professor Ian Rae, a University of Melbourne expert on chemicals, told the AusSMC this research added to the evidence that PFAS could have harmful health effects.
"Many other epidemiological (population-based) studies have shown correlations between exposure and a range of health effects. But taking the next step, establishing cause and effect beyond just correlation, is not really possible by population studies," Prof Rae said.
"Much more research would be needed for that, such as establishing the exact mechanism by which harm is caused. The authors acknowledge this, calling for repetition of their work, but also claiming that there is already a biologically plausible link between between exposure and the effects they have studied. That is, there is at least some notion of the likely biological mechanism."
Associate Professor Peter Franklin, Director of Occupational Respiratory Epidemiology at the University of Western Australia, said the link between asthma and PFAS in this study was only visible at a very high level of exposure.
"The current study found that exposure to PFAS during pregnancy increased the risk of developing asthma in childhood. However, the risk was only observed in the study’s ‘very high’ exposure group. There was no increased risk in children born to mothers in either the ‘high’ or ‘intermediate’ exposure groups," A/Prof Franklin said.
He said even the lower levels of PFAS exposure around Ronneby were very high in a more global context as the contamination the region experienced was so extreme.
"The average potential PFAS concentrations in mothers in the ‘very high’ exposure group were many times greater than what has been found in the general population, and even much higher than what was found in high exposure risk groups in Australia, i.e. around airforce bases at Oakey, Williamtown and Katherine. Even the ‘high’ and ‘intermediate’ groups had much greater average PFAS concentrations than those high exposure risk groups in Australia."
Dr Farzana Kastury from Adelaide University said the median concentration of PFAS in the 'very high' group was "at least 10 times higher" than the levels reported in Australian communities exposed to PFAS from firefighting foam.
"Therefore, the results from Blomberg et al., (2026) may not be directly relevant to the majority of Australians, albeit, it adds an important piece of evidence of PFAS’s immunotoxicity at very high exposure levels," Dr Kastury said.
Chemistry Professor Oliver Jones from RMIT University said there were also limitations to this kind of study when it came to confirming a link between PFAS and asthma.
"Firstly, the children's exposure to PFAS was not directly measured, but estimated based on their addresses and how long they lived there. We don’t know how much PFAS they were actually exposed to," Prof Jones said.
"Secondly, what has been reported is an association, not a direct relationship. It does not prove causation. One might find a statistical association between asthma and any number of factors, but that does not automatically prove that one caused the other. It just gives you an idea of what might be worth exploring further."
He said previous studies on the topic had not been able to establish a similar link between PFAS and asthma, and agreed that few if any other communities around the world had likely been exposed to PFAS at this scale.
"Thus, even if everything in this paper is correct, the results are likely to apply only to this specific town - so, I would say Australians do not have to worry about PFAS giving us asthma," he said.
You can read the full Expert Reaction here
This article originally appeared in Science Deadline, a weekly newsletter from the AusSMC. You are free to republish this story, in full, with appropriate credit.
Contact: Rachel McDonald
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