Stephanie Engel, Ph.D.
University of North Carolina at Chapel Hill
R01ES021777, T32ES007018, P30ES010126
Elevated levels of phthalates during pregnancy may negatively affect executive function in children, according to a new NIEHS-funded study. Some changes were especially prominent among boys. Executive function is a set of complex cognitive skills, such as emotional regulation, impulse control, working memory, and attentional flexibility. Executive function enables people to focus, follow directions, and handle emotions, among other things.
Researchers measured 12 phthalate metabolites in urine samples collected at 17 weeks of pregnancy. Among those children sampled, born between 2003 and 2008, the researchers compared 262 children who are affected by attention-deficit hyperactivity disorder symptoms with 78 typically developing children. All children participated in a detailed clinical assessment at 3.5 years, including three performance-based tests and behavior information collected from parents and caregivers.
Exposure to higher levels in maternal blood of mono-benzyl phthalate (MBzP) during the prenatal period was associated with poorer executive function in both sexes. Specifically, MBzP was associated with effects on working memory, emotional control, and inhibition as rated by parents and teachers and evaluated in administered tests.
Affected executive function was also related to higher levels of mono-n-butyl phthalate and mono-iso-butyl phthalate, although results varied by evaluation method. For example, inhibition reported by parents was most affected by both chemicals, with stronger associations among boys. However, no differences were found between girls and boys when considering inhibition rated by teachers or by the three performance tests.
According to the researchers, the prenatal period may represent a critical window of exposure where phthalates may harm later executive functioning, particularly for boys.
Citation: Choi G, Villanger GD, Drover SSM, Sakhi AK, Thomsen C, Nethery RC, Zeiner P, Knudsen GP, Reichborn-Kjennerud T, Overgaard KR, Herring AH, Skogan AH, Biele G, Aase H, Engel SM. 2021. Prenatal phthalate exposures and executive function in preschool children. Environ Int 149:106403.