Phthalates, a class of chemicals known to interfere with hormonal function and development, pose a risk of cognitive decline when a child is born if the expectant mother is overexposed to them.
- Children whose mothers have had high exposures to phthalates have slower information processing compared to others.
- Little boys were more likely to process information slowly if their mother had been exposed to high concentrations of phthalates.
Plastics and brain development do not mix. Phthalates, chemicals used in the manufacture of plastic objects to make them more flexible, have been linked to reduced brain processing speed in infants when the mother was exposed to them at high levels. This observation was revealed by American researchers from the University of Illinois Urbana-Champaign. They presented these results in a study published on February 13 in theInternational Journal of Environmental Research and Public Health.
A hormone-disrupting chemical
This research is part of the Illinois Kids Development Study (IKIDS), which tracks the effects of hormone-disrupting chemicals on the physical and behavioral development of children from birth through childhood. The IKIDS study, now in its seventh year, has recruited hundreds of participants and is tracking the chemical exposure of pregnant women and the development of their children.
“IKIDS is part of a larger initiative funded by the National Institutes of Health, the Environmental Influences on Child Health Outcomes program. It tracks the impact of prenatal chemical exposures and maternal psychosocial stress on child growth and development over timesaid the study’s lead author Susan Schantz, a neurotoxicologist and professor of comparative biosciences at the University of Illinois Urbana-Champaign. We measure many birth outcomes, including birth weight and gestational age. We also assess infants’ cognition by studying their observing behavior. This allows us to obtain measures of working memory, attention and information processing speed.”
The most affected boys
The researchers measured the exposure to phthalates of pregnant women participating in the study by analyzing the metabolites of three common phthalates in regularly collected urine samples. These data were used in combination with the assessments of 244 infants, aged 7.5 months. For this, they are shown two video events to the child, one familiar and the other unfamiliar. Infants tend to watch unfamiliar videos or events longer, which helps set some brain processing speed. The researchers then used an infrared eye tracker to track each child’s gaze during several lab trials. In this experiment, researchers familiarized infants with two identical images of a face and, once the infant learned to recognize it, showed that same face paired with an unfamiliar face. “By analyzing the time spent looking at faces, we were able to determine both the speed at which infants processed new information and assess their attention span.”, observed Susan Schantz.
The results showed a difference in the speed of cerebral processing between the children and made it possible to establish a link between the exposure of pregnant women to most of the phthalates tested and the slowing down of information processing in their infants. In detail, the results were different depending on the chemical to which the mother was exposed, the gender of the baby and the series of faces considered familiar by the latter. Little boys were more likely to process information slowly if their mother had been exposed to high concentrations of phthalates. “Most previous studies on the relationship between prenatal phthalate exposure and cognition have focused on infancy and middle childhood.concluded the researcher. This new work suggests that some of these associations can be detected much earlier in a child’s life..”
.