Exposure to phthalates, a class of chemicals widely used in packaging and consumer products, is known to interfere with normal development and hormonal function in human and animal studies. Researchers have now found evidence linking pregnant women’s exposure to phthalates to altered cognitive outcomes in their babies.
Most of the results involved slower information processing among infants with higher phthalate exposure levels, with males likely to be affected depending on the chemical involved and the order of information presented. to babies.
Informed in the magazine Neurotoxicology, the study is part of the Illinois Kids Development Study, which tracks the effects of hormonal-altering chemicals on children’s physical and behavioral development from birth to middle childhood.
Now, for the seventh year, IKIDS has enrolled hundreds of participants and monitors chemical exposures in pregnant women and developmental outcomes in their children. Susan Schantz, a neurotoxicologist and professor emeritus of comparative biosciences at the University of Illinois Urbana-Champaign, is the study’s lead researcher. He is a faculty member at the Beckman Institute for Advanced Science and Technology, which hosts the IKIDS program in Illinois.
IKIDS is part of a larger initiative funded by the National Institutes of Health, the Environmental Influences on Child Health Outcomes program. The impact of prenatal chemical exposures and maternal psychosocial stress on children’s growth and development over time is monitored. We measure numerous birth outcomes, including birth weight and gestational age. We also assess babies ’cognition by studying their gaze behavior. This allows us to obtain measures of working memory, attention and speed of information processing. “
Susan Schantz, neurotoxicologist and professor emeritus of comparative biosciences, University of Illinois Urbana-Champaign
The researchers analyzed frequent three-phthalate metabolites in urine samples collected regularly from the study’s pregnant women. Chemical exposure data were used in combination with assessments of female infants when the children were 7.5 months old.
The researchers used a well-established method that allows them to know the reasoning of children too young to express themselves verbally: babies tend to look at images or unknown or unexpected events longer.
The team used an infrared eye tracker to track each child’s gaze during various lab tests. With the baby sitting on a caregiver’s lap, the researchers familiarized the child with two identical one-sided images. After the baby learned to recognize the face, the researchers showed that the same face combined with an unknown one.
“In repeated tests, half of the 244 babies tested saw that a set of faces was familiar and half learned to recognize a different set of faces as familiar,” Schantz said. “By analyzing the time spent looking at faces, we could determine how quickly babies were processing new information and assess their ability to pay attention.”
The assessment related the exposure of pregnant women to most phthalates that were evaluated with slower information processing in their infants, but the outcome depended on the specific chemical, the sex of the baby, and of the set of faces the baby considered familiar. Male infants, in particular, tended to process information more slowly if their mothers had been exposed to higher concentrations of phthalates that are known to interfere with androgenic hormones.
The specific characteristics of the faces presented to infants in familiarization trials also appeared to play an important role in the outcome, the researchers reported. Children exposed to phthalates who were first familiar with the faces of set 2 were more likely to experience a slower processing speed than those familiar with the faces of set 1.
The finding is puzzling, Schantz said, but it’s probably related to differences in babies’ preferences for the faces of the two sets. It may also be an indication that familiarity with the faces of set 2 is a more sensitive detector of changes in processing speed related to phthalate exposure.
“Most previous studies on the relationship between prenatal phthalate exposure and cognition have focused on early and middle childhood,” Schantz said. “This new work suggests that some of these associations may be detected much earlier in a child’s life.”
University of Illinois at Urbana-Champaign, News Bureau
Dzwilewski, KLC, et al. (2021) Associations of prenatal phthalate exposure with cognition measures in 7.5-month-old infants. NeuroToxicology. doi.org/10.1016/j.neuro.2021.03.001.