- Posted April 10, 2026
Heavy 'Forever Chemical' Exposure Before Birth Increases Childhood Asthma Risk, Study Finds
Babies exposed to PFAS “forever chemicals” in the womb have a higher risk of developing childhood asthma, a new study says.
Very high prenatal exposure to PFAS appears to increase children’s risk of asthma by 44%, researchers reported April 9 in the journal PLOS Medicine.
The new study focused on Ronneby, a town in southern Sweden where part of the city water supply was contaminated by runoff from a military airfield.
PFAS levels in tainted drinking water were more than 200 times higher than those of neighboring public water systems.
Researchers compared children born in Ronneby to those born in its county as a whole.
“We found that children whose mothers were exposed to very high levels of PFAS during pregnancy had a substantially higher incidence of clinically diagnosed asthma,” lead investigator Annelise Blomberg said in a news release. She’s an associate researcher in epidemiology at Lund University in Sweden.
PFAS are called “forever chemicals” because they combine carbon and fluorine molecules, one of the strongest chemical bonds possible. This makes PFAS removal and breakdown very difficult.
PFAS compounds have been used in consumer products since the 1940s, including fire extinguishing foam, nonstick cookware, food wrappers, stain-resistant furniture and waterproof clothing.
These chemicals are known to affect the immune system, which might play a role in the development of asthma, researchers said.
For the new study, they examined all children born in Blekinge County, including Ronneby, between 2006 and 2013.
PFAS contamination in one of Ronneby’s two municipal waterworks came to light in 2013, researchers said in background notes. By that point, about a third of city households had been drinking tainted water for decades.
The total PFAS concentration in the contaminated water was 216 times the 48 ng/L level in Ronneby’s other water system, researchers said. A neighboring city had levels below 5 ng/L.
In 2014 and 2015, monitoring found extremely high PFAS levels in blood tests of 3,300 Ronneby residents, researchers noted.
This tragedy provided researchers an opportunity to better examine the potential health effects of PFAS chemicals on newborns and children.
“Most previous research has examined populations exposed only to background levels of PFAS,” and results were inconclusive, Blomberg said.
“In Ronneby, drinking water contamination resulted in exposure levels hundreds of times higher than the general population,” she continued. “This allowed us to evaluate potential health effects across a much broader exposure range.”
Researchers used mothers’ addresses to estimate their exposure to PFAS-contaminated water, then tracked their children’s health using national patient data.
About 18% of children were diagnosed with wheeze and 17% with asthma during follow-up, researchers reported.
Exposure to the extreme PFAS levels in Ronneby’s water was linked to a 44% higher risk of asthma.
In all, about 16% of children exposed to low background levels of PFAS were diagnosed with asthma, compared to 27% with high levels of exposure, the study says.
No link was found between PFAS and asthma at lower exposure levels, “which may help explain why previous studies in general populations have reported mixed results,” Blomberg said.
“These results point to a substantial and previously unrecognized public health consequence of PFAS contamination,” researchers concluded.
Blomberg said future studies should follow a similar strategy, to gain a better understanding of how PFAS exposure might affect health.
“Our findings suggest that very high prenatal exposure may have lasting consequences for children’s respiratory health,” she said.
“At the same time, replication in other highly exposed populations will be important to confirm these results,” Blomberg added.
As researchers work to learn more, parents with concerns can reach out to their public water supply to ask about PFAS levels in local drinking water. If levels are high, there are in-home water treatments systems that can filter out PFAS, according to the U.S. Environmental Protection Agency.
More information
Stanford Medicine has more about PFAS and human health.
SOURCES: PLOS, news release, April 9, 2026; PLOS Medicine, April 9, 2026
