Severe Exposure to ‘Forever Chemicals’ During Pregnancy Could Lead to Childhood Asthma

A new Swedish study focuses on very high levels of PFAS exposure in drinking water.

Exposure to “forever chemicals” during pregnancy could increase the risk of childhood asthma, according to new research from Sweden.

Researchers from Lund University found that prenatal exposure to very high levels of per- and polyfluoroalkyl substances, known as PFAS, in drinking water corresponded with a higher incidence of childhood asthma in a community dealing with decades of contamination.

The findings, published Thursday in PLOS Medicine, are notable. Although PFAS exposure causes myriad well-documented health harms, links to asthma have not been as well-studied.

“When I went into it, I was not expecting to see anything, so we were surprised,” said Annelise Blomberg, an associate researcher in epidemiology at Lund University and a study co-author.

Researchers emphasized that the association they found was limited to very high levels of PFAS exposure and said the research needs to be replicated. Still, it has implications for people around the world who are exposed to high levels of forever chemicals.

“This is a public health effect that has gone really undetected until now,” Blomberg said. 

The study adds to an already long list of demonstrated ways that PFAS exposure harms human health and a growing list of environmental asthma drivers. Researchers have called childhood asthma a “global epidemic,” with rates rising in recent decades. As threats to lung health compound with worsening air pollution, toxic exposures and heat amplified by climate change, it is a critical time to understand the drivers of respiratory disease.

PFAS, or forever chemicals, have been widely used in many consumer products since the 1940s. They’re now everywhere, found in drinking water, fish, livestock and more. The new study focused specifically on aqueous film forming foam, or AFFF, a fire suppressant that contains several hazardous PFAS.

Residents of Ronneby, a city in southern Sweden, were unknowingly exposed to water with high levels of PFAS for more than 30 years, after AFFF runoff from a local military airfield contaminated one of two municipal waterworks. By the time the contamination was discovered and the water system was shut down in 2013, about a third of the city’s residents had consumed highly contaminated water for years. Later tests found extremely elevated PFAS levels in their blood. 

The researchers followed a cohort of more than 11,000 children born between 2006 and 2013 in the area until age 12 or the end of 2022. The researchers used water distribution records and parents’ addresses to approximate prenatal exposure to PFAS, categorizing the exposure levels based on the pregnant parents’ addresses during the five years before birth. Children born to a parent who lived at an address receiving contaminated water for all five years before the child’s birth were put in the “very high” exposure category.

After controlling for factors like socioeconomic status and parental smoking, the researchers found that children with very high levels of prenatal PFAS exposure had about a 40 percent higher risk of developing childhood asthma than children outside the exposure area. No increase was found for children with high or intermediate exposure.

“The majority of the people in the study, we saw no effect,” said Anna Saxne Jöud, an associate professor of epidemiology at Lund University and another co-author. “We want to help people that are worried to understand what they need to be worried about, but we also want to communicate what, to our best knowledge, they don’t need to worry about.”

Tracey Woodruff, a professor of epidemiology at Stanford University who was not involved with that research, said the study was well done and very interesting. The large sample size makes the results particularly compelling, she said, as does the urgency of its focus. 

“This area of immune function is so highly understudied and undervalued in environmental health,” said Woodruff, a former senior scientist at the U.S. Environmental Protection Agency. 

She said that’s exacerbated by government neglect, underinvesting in this area of research and failing to make industry provide sufficient data so scientists can understand how chemical exposures impact immune function. Woodruff pointed to the Trump administration’s decision to eliminate the EPA’s Office of Research and Development as a blow to understanding and regulating PFAS contamination. 

“The EPA has been actively destroying parts of the agency that are critical to identifying toxic chemicals and their impact on health,” Woodruff said. 

The new study has limitations. One is the use of addresses to approximate PFAS exposure, Blomberg said. Some levels of exposure might be miscategorized, and it’s difficult to distinguish between exposure in the womb and during childhood, given that many of the children in the study continued to live at the same address, drinking the contaminated water.

“We can’t really say it’s the prenatal window that matters, because the kids still had early-life exposure as well,” Blomberg said. “We can’t fully distinguish those effects.”

Blomberg and Jöud said they want to see the study replicated in other high-exposure populations globally.

Woodruff said further research is important, but she also wants to see governments clean up existing PFAS and prevent further contamination. 

“We know a lot about PFAS exposures,” she said. “We also need [to be] taking actions.”

Cover photo:  Aqueous film forming foams used to fight certain fires contain so-called forever chemicals. Credit: Bastiaan Slabbers/NurPhoto via Getty Images