Exposure to phthalates, cognitive development, and visual behavior in children

How to measure a child's "visual behavior"?

Around their second year, 151 children from the SEPAGES cohort visited the babylab on the campus of the Université Grenoble Alpes. The visit to the baby lab involved performing oculometry tasks. The child sat on their parents' laps and looked at a screen displaying various visual stimuli. This examination allowed for the collection of precise and quantitative measures of the child's cognitive and social development. These measures complement the data collected through questionnaires in SEPAGES.
Tasks performed at the baby lab, for example, quantify the duration of fixation on objects or faces. This provides insight into the child's attention, which is an important aspect of cognitive development. The examination also allows for studying the time spent observing a new face, providing information about the child's memory and learning abilities.

What pollutants were studied?

Samples of urine collected during pregnancy and at one year of age were used to measure exposure to different phthalates. The significant number of urine samples (42 samples during pregnancy and 7 around one year of age) provides precise exposure assessment to phthalates.

Results

The main results of the study suggest that:

• 1) prenatal exposure to certain phthalates was associated with shorter visual fixation durations in toddlers, particularly in girls;
• 2) postnatal exposure was associated with changes in visual attention and reaction times.

These results underscore the specific effects of phthalates on the development of young children.

What makes this study innovative?

The novelty of this study lies in the precise evaluation of multiple phthalate exposures and objective measures of neurological development in early childhood. This study also investigates the effect of phthalate exposure on child development at two important periods: during pregnancy and in the first year of life.

What are the next steps?

The research team will continue its investigation into the effect of phthalates on:

• 1) child growth
• 2) biological mechanisms.

The research team will examine whether phthalate exposure may have a deleterious effect on hormone functioning, notably cortisol and thyroid activity, which play an essential role in the healthy development of the central nervous system.