CHAMPAIGN, Ill. — For more than a decade, researchers at the University of Illinois Urbana-Champaign have tracked the health of hundreds of children, focusing on their chemical exposures, both prenatally and as they mature, finding associations between these exposures and the kids’ cognitive development.
The oldest children in the Illinois Kids Development Study are now 12. Based at the University of Illinois Urbana-Champaign, IKIDS is a part of Environmental Influences on Child Health Outcomes, a national research program supported by the National Institutes of Health "to enhance the health of children for generations to come." IKIDS focuses on child neurodevelopment in the pre-, peri- and postnatal period and is following the kids through middle childhood. It also contributes to studies focusing on other dimensions of child health and well-being.
Twelve-plus years of research have added significantly to the scientists’ understanding of how chemical exposures — in the womb and after — may influence a child’s brain development and behavior, said U. of I. comparative biosciences professor emerita Susan Schantz, the original IKIDS director who continues as a co-principal investigator with her colleagues, comparative biosciences professor Andréa Aguiar and Michigan State University food science and human nutrition professor Rita Strakovsky. Aguiar is the IKIDS director.
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IKIDS began recruiting pregnant parents in 2012 and joined the ECHO program in 2016. In the first wave of its work, it enrolled 565 mother-child pairs residing in the Urbana-Champaign region, Aguiar said. A new round of ECHO funding started in 2023 and will continue until 2030. The IKIDS’ goal is to enroll another 600 local mother-child participants.
The IKIDS studies have focused on chemical exposures that are widespread in the U.S. population, Schantz said. These include over-the-counter medicines like acetaminophen; chemicals in plastics and food packaging like bisphenols and phthalates; antimicrobials like triclosan in soaps, toothpaste and other consumer products; agricultural chemicals like glyphosate; and chemicals that are added to or leach into the water supply, like fluoride and per- and polyfluoroalkyl substances.
The studies also look at cognitive developmental outcomes.
It’s challenging to know what’s going on in the infant brain, but eye-tracking studies are a useful metric, Aguiar said. Even in infancy, children begin to recognize familiar and unfamiliar objects, scenes or behavioral patterns in the people around them. If something violates the pattern — "for example, if a ball rolls behind a chair but doesn’t appear between the legs of the chair as expected," Aguiar said — an infant of eight weeks who is developing at a normal pace will spend more time staring at it. If a child of this age does not stare longer at a similar unusual event or an unfamiliar face appearing next to a familiar face, it can signal a developmental delay.
Other tests in older children — of their language development or ability to regulate their behaviors or emotions — can also signal neurodevelopmental problems or delays.
So far, IKIDS has found evidence linking phthalates, phenols like bisphenols, triclosan, acetaminophen and even maternal stress to disruptions or delays in cognitive and language development, the researchers said.
"We’re finding different patterns with different chemicals and different exposures," Schantz said.
For example, the team reported that higher acetaminophen exposure in the second trimester of pregnancy was associated with increased attention and behavior problems in 3- and 4-year-olds. Another analysis linked increasing acetaminophen exposure during pregnancy with language delays.
An earlier study linked prenatal phthalate exposure to altered information-processing in infants. Even exposure to maternal stress correlated with cognitive delays in some infants.
"Maternal stress had more of an impact on female infants, and phthalates tended to have more of an impact on male infants," Schantz said.
Other hormone-mimicking chemicals that are often found in food packaging, like bisphenols, are associated with neurodevelopmental delays. Even the bisphenols that were introduced after bisphenol A was phased out because of health concerns have some negative impacts, Aguiar said.
"Our results suggest that chemicals like bisphenol S and bisphenol F, which some are calling the 'regrettable replacements,' appear to be problematic for emotional control in 2-year-old girls and neurodevelopment in 1-year-old babies, respectively," she said. "These are subtle effects, but we know from other studies that very subtle disruptions early in development can lead to bigger problems later on."
The research into "forever chemicals" such as per- and polyfluoroalkyl substances, or PFAS, yielded "no significant effects" on children’s neurodevelopment, the team found. "It doesn’t mean that PFAS are benign," Schantz said. "There’s much clearer negative effects on the immune system and the thyroid hormones."
Their studies of triclosan, an antibacterial agent found in soaps and other consumer products, and benzophenone, a sunscreen, found "some associations of exposure to poorer attention and slower information processing," Aguiar said.
This work will continue at least until the current ECHO grant ends in 2030. The IKIDS program is working to recruit a more diverse pool of pregnant participants than in the original cohort, Aguiar said. Outreach is being conducted on several fronts, including in Spanish and through the local public health department, Promise Healthcare in Champaign and CarleHealth’s obstetrics and gynecology clinic in Urbana.
Current and future studies are investigating associations between child neurodevelopment and prenatal exposures to fluoride, the herbicide glyphosate "or other prenatal exposures that are widespread in the U.S. population," Aguiar said.
The IKIDS cohort was initiated with a grant jointly funded by the National Institute of Environmental Health Sciences at the National Institutes of Health and the U.S. Environmental Protection Agency and has been expanding since 2016 with support from the National Institutes of Health, ECHO program.
