OPS 23: Chemicals and cognitive function, Room 114, Floor 1, August 28, 2019, 1:30 PM - 3:00 PM
Background: Accumulating evidence links prenatal phthalate exposure to poor neurodevelopment, implying impaired executive function (EF). However, few studies of prenatal phthalate exposure have included a detailed assessment of EF.
Aim: To evaluate the relationship between prenatal phthalate exposure and EF in preschool children.
Methods: Norwegian Mother and Child Cohort (MoBa) Preschool ADHD Substudy participants provided a urine sample upon enrollment, at 17-weeks’ gestation, from which 12 phthalate metabolites were assayed. Amongst the MoBa enrollees, a sample of children with (n=262) or without (n=78) preschool ADHD symptoms underwent a clinical assessment. The test results characterizing EF were selected for analyses: inhibition, working memory, and emotional control from the parent- and teacher-completed Behavior Rating Inventory of Executive Function–Preschool version (BRIEF), statue test from NEPSY, nonverbal and verbal working memory from the Stanford-Binet intelligence test, and a cookie delay test. Change outcome score per interquartile range (IQR) increase in phthalates (β) was estimated with multivariable linear regression, adjusting for maternal (ADHD, BMI, age, parity) and child (birth year, sex) characteristics. To account for over-sampling by preschool ADHD symptoms, weighted analyses were conducted. We assessed interactions by sex and confounding by phthalate co-exposures.
Results: An IQR increase in prenatal monobutyl phthalate (MBzP) was consistently associated with poorer EF measured on all tests. For example, an IQR increase in MBzP was associated with poorer BRIEF working memory (β: 1.35; 95% confidence interval, CI: 0.7, 1.99), in both sexes. In addition, mono-n-butyl phthalate (MnBP) and monoisobutyl phthalate (MiBP) were associated with poorer EF, but only among boys (MnBP and BRIEF inhibition β: 1.16; 95% CI: 0.60, 1.72; and MiBP and BRIEF inhibition β: 1.16; 95% CI: 0.63, 1.70). Co-exposure to other phthalates did not confound associations.
Conclusion: Elevated prenatal MBzP, MnBP, and MiBP were associated with poorer preschool EF. Some associations were found only among boys.