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Effects of early exposure to phthalates on cognitive development and visual behavior at 24 months
Matthieu Rolland1, Sarah Lyon-Caen1, Cathrine Thomsen2
1Team of Environmental Epidemiology Applied to Reproduction and Respiratory Health, Institute for Advanced Biosciences (IAB), Grenoble Alpes University, Inserm, CNRS, 38700 La Tronche, France.
Insights
Prenatal and infant phthalate exposure impacts neurodevelopment, particularly in girls, affecting visual attention and reaction times. This study used objective eye-tracking measures to assess cognitive development at age two.
Area of Science:
- Environmental Health
- Neuroscience
- Developmental Pediatrics
Background:
- Few studies examine phthalate exposure during infancy, a critical neurodevelopmental window.
- Parental questionnaires for neurodevelopmental assessment are prone to reporting errors.
- This study investigates phthalate exposure and objective neurodevelopmental measures in early childhood.
Purpose of the Study:
- To assess the association between prenatal and infant phthalate exposure and neurodevelopmental outcomes at age two.
- To utilize objective eye-tracking metrics for evaluating cognitive development and visual behavior.
- To explore sex-specific effects of phthalate exposure on neurodevelopment.
Main Methods:
- 151 mother-child pairs from the SEPAGES cohort provided urine samples during pregnancy and infancy.
- Phthalate metabolites were quantified in pooled urine samples.
- Eye-tracking tasks at age two yielded measures of fixation duration, novelty preference, eye-gaze, and reaction time.
Main Results:
- Prenatal monobenzyl phthalate exposure was linked to shorter fixation durations, primarily in girls.
- Third-trimester di(2-ethylhexyl) phthalate exposure correlated with increased looking time at novel faces and eyes.
- Postnatal exposure to certain phthalates was associated with faster reaction times and reduced eye-gaze in face recognition tasks.
Conclusions:
- Improved exposure assessment revealed phthalate associations with eye-tracking indicators of neurodevelopment, predominantly in girls.
- These findings highlight potential neurodevelopmental impacts of phthalates, with implications for individuals with neurodevelopmental disorders.
Background And Objectives:
Studies focusing on the neurodevelopmental effects of phthalates seldom consider exposure during infancy, a critical period for brain development. Most rely on parent-completed questionnaires to assess child neurodevelopment, which may be subject to reporting error. We studied the associations between prenatal and infancy exposure to phthalates and objective measures of neurodevelopment at the age of two.
Methods:
We relied on 151 mother-child pairs from the SEPAGES mother-child cohort. Women were asked to collect three spot urine samples per day over seven consecutive days during the second (median: 18.0 gestational weeks) and third (median: 34.2 gestational weeks) trimesters of pregnancy. They then collected one urine sample per day over seven consecutive days from their infants around the age of 12 months. Metabolites of phthalates and non-phthalate plasticizers were measured in within-subject and within-period pools of repeated urine samples. Eye tracking tasks were performed at two years allowing to compute four indicators linked with cognitive development and visual behavior: mean fixation duration, novelty preference, percent time spent looking at the eyes and mean reaction time.
Results:
Pre-natal exposure to monobenzyl phthalate at the second and third trimesters was associated with shorter fixation durations. In models allowing for interaction with child sex, these associations were only observed among girls. Exposure to di(2-ethylhexyl) phthalate at the third but not the second trimester was associated with increased time spent looking at a novel face and eyes. We observed faster reaction times and decreased time spent looking at the eyes in a face recognition task, with increased post-natal exposure to monoethyl, mono-iso-butyl and mono-n-butyl phthalates.
Discussion:
Relying on improved exposure assessment, we highlighted associations of pre- and post-natal exposure to phthalates with indicators derived from eye tracking tasks, mainly in girls. Some of these indicators have been affected in individuals with neurodevelopmental disorders.
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