‘Forever chemicals’ (PFAS) may weaken immune function in children, leading to more frequent infections 

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(Photo courtesy of Wisconsin Department of Health Services) 

Drinking water contaminated by human-made “forever chemicals” appears to impair children’s immunity, potentially increasing the risk of common childhood infections, new research shows.

The study, which appears in the March 1 [2025] issue of Environmental Research, is the first and largest to investigate the association between high prenatal levels of perfluoroalkyl and polyfluoroalkyl substances (PFAS) and clinically diagnosed common infections in children, say the researchers, led by Matilda Ebel of Lund University in Sweden.

The researchers investigated an unusually wide range of exposure to PFAS, including perfluorooctanesulfonic acid (PFOS) and perfluorohexanesulfonic acid (PFHxS), from low level (background) to very high levels in a Swedish community whose drinking water had been severely contaminated.

They found children aged 6 months to 7 years with very high prenatal exposure had a 28% increased risk of ear infections, and possibly also eye and urinary tract infections, across all age groups, the study shows. Gender did not appear to affect the relationship between exposure and these health outcomes.

PFAS are endocrine-disrupting chemicals commonly used in consumer products that persist in the environment and can accumulate in humans and animals. They have been linked to cancer, birth defects, liver disease, thyroid disease, decreased immunity, hormone disruption, and a range of other serious health problems.

Some impacts differ based on age, PFAS exposure

Researchers also broke down the study by level of exposure and age—from 6 months to 3 years and 4 to 7 years. They say they did this for two main reasons: First, younger and older children may react differently to PFAS exposure because their immune systems are still developing. Second, parents are more likely to seek medical care for younger children, which could affect the results.

The study shows:

The European Food Safety Agency has said that reduced immune response to vaccination is the most critical health effect of exposure to PFAS. Studies have found a reduced antibody response to childhood vaccines for diphtheria, tetanus, rubella, and measles. That means the immune system doesn’t produce as many protective proteins as it should to recognize and fight off a virus or bacteria.

While studying weakened vaccine responses can show how PFAS affects the developing immune system, looking at diagnosed infections provides more meaningful clinical insights, the researchers say.

“Although the explicit mechanisms for such an effect are unknown, the fact that we observed suggestive associations with several types of common infections suggests an impact of exposure on general immunity,” they say.

“Hotspot” provided a living opportunity to study PFAS exposure

It’s estimated that more than 2,100 areas have PFAS levels higher than usual, called “hotspots.” New hotspots are often found around the world, and people living in these areas might be at a greater risk for health problems related to PFAS exposure, the researchers say.

In the U.S., the EPA has identified more than 120,000 such locations with facilities in industries related to oil and gas work, mining, chemical manufacturing, plastics, waste management, and landfill operations. They also include airports, fire training facilities, and some military-related sites, according to a 2021 report in The Guardian.

Ronneby, in the south of Sweden, is one of these hotspots, where drinking water was discovered in 2013 to be contaminated by a substance used in firefighting foam. About one-third of the households were unknowingly drinking contaminated water for a long time, while the rest of the town received clean water from a different source.

The contaminated water had very high levels of two types of PFAS: PFOS (8000 ng/L) and PFHxS (1700 ng/L), far higher than the Swedish safety limit of 90 ng/L for PFAS.

Between 2014 and 2016, testing confirmed large differences in PFAS levels among the population, the researchers say. 

Women aged 21–38 who lived in the area with contaminated water had about three times the levels of PFOS, PFHxS, and PFOA in their blood compared to women in the same age group who lived in the area but got water from the clean water plant.  Women living in nearby areas with uncontaminated water had significantly lower levels of PFAS.

For this study, the researchers looked at the health registry records of all children born between 2003 and 2013 (before the discovery of the contamination) to mothers who were registered as living in Blekinge County at any time between 6 months and 7 years of age. Multiple births were excluded, and the researchers accounted for maternal smoking in early pregnancy and age, among other factors.

The final study population consisted of 17,051 children. Of these:

Among other limitations, researchers looked only at doctor-diagnosed cases of eye, ear, respiratory, and urinary tract infections. Parents, in some cases, might not choose to seek primary care attention for infections with mild symptoms, they note.

Also, although the researchers used the mother’s address before delivery to determine exposure, many families in the exposed area continued to live there after birth. That means the study couldn’t fully compare the effects of prenatal exposure to the effects of exposure during early childhood, they say.

More research is needed to investigate whether children born prematurely, who are known to be more likely to get infections, are at higher risk of infection compared to children born full term, the researchers say. Breastfeeding could also affect the link between prenatal PFAS exposure and infections in childhood.

A previous study found that high PFAS exposure was linked to shorter breastfeeding durations, and this could affect the development of a child’s immune system, the researchers say.

“More research on early-life exposure to PFAS and clinical infections, especially the risk of eye infection, across a range of exposures is needed to establish these associations,” they say. “This study adds important knowledge as it investigates a highly exposed population, and new contaminated areas are continuously discovered worldwide.”

To find out if PFAS is in your drinking water and if it is, reduce your exposure, the EPA suggests reaching out to your local water utility to learn about how they may be addressing PFAS and ask them to test the water for PFAS or to share information with you if they have already tested the water. NOTE: Some public drinking water systems may not have this information. If you choose to test your water yourself, it is important to use a state-certified laboratory using EPA-developed testing methods.

The EPA also recommends: “If you remain concerned about the level of PFAS in your drinking water, you can contact your state environmental protection agency or health department and your local water utility to find out what actions they recommend. Consider installing in-home water treatment (e.g., filters) that are certified to lower the levels of PFAS in your water. Learn about certified in-home water treatment filters.”

Reference

Ebel M, Blomberg AJ, Bolmsjö BB, Jöud AS, Jensen TK, Nielsen C. Common infections in children aged 6 months to 7 years after high prenatal exposure to perfluoroalkyl substances from contaminated drinking water in Ronneby, Sweden. Environmental Research. 2025;268:120787-120787. doi:https://doi.org/10.1016/j.envres.2025.120787