Effects of Prenatal Phthalate Mixtures on Childrens’ Externalizing Behaviors in Middle Childhood

• In Event: The Effects of Early Life Environmental Toxicants on Neurodevelopment From Early to Middle Childhood

Abstract

Introduction: Problem behaviors in middle childhood negatively impact children’s later development, including poor academic outcomes and lower overall mental well-being. Exposure to phthalates—non-persistent endocrine disrupting chemicals— have been implicated in the etiology of children’s behavior problems, but this evidence is not consistent, and associations may vary by child sex. Pregnant women are a particularly vulnerable population given the ability of the chemicals to cross the placenta and directly influence fetal development, marking the prenatal period as a critical window of susceptibility, particularly for boys. However, few studies consider the potential amplified risk of multiple phthalate exposures as humans are exposed to multiple chemicals simultaneously. Therefore, this study attempts to examine the association between prenatal exposure to phthalate mixtures on children’s externalizing behaviors by using a person-centered method, Latent Profile Analysis, within an inner-city New York cohort of mother-child dyads.
Hypotheses: We hypothesized that (1) we would find multiple groups of exposures characterized by low molecular weight phthalates and high molecular weight phthalates and (2) the high exposure groups would be associated with higher levels of externalizing behaviors in boys compared to girls.
Study Population: The sample is 404 mother-child dyads from the Mount Sinai Children’s Environmental Health Study. This is a prospective, multiethnic cohort of pregnant mother-child dyads with singleton pregnancies from inner city New York. The majority of children (54.9% male) identified as an ethnic minority (79.0%).
Methods: Prenatal exposure to phthalates was assessed with maternal urine samples collected between 25 and 40 weeks gestation. Children’s externalizing and hyperactivity behaviors were assessed using maternal report on the Behavior Assessment System for Children – 2nd edition at 7-9 years old. Latent profile analysis was used to group phthalate metabolite levels and then analyses were conducted examining the associations with child externalizing behaviors. In addition, we examined moderation by child sex.
Results: Results showed that there were four profiles of prenatal phthalate exposure: (1) low exposure across all phthalate metabolites, (2) average exposure across all phthalate metabolites, (3) high exposure across all phthalate metabolites, and (4) highest DEHP and MEP phthalate metabolite exposure. We found that mothers of color were more likely to be in the higher phthalate exposure groups compared to white mothers, and older mothers were more likely to be in the high DEHP and MEP exposure group compared to younger mothers. The profiles of exposure were not associated with children’s externalizing behaviors overall. We examined moderations by child sex and found that girls with mothers in the elevated prenatal phthalates exposure group had lower levels of externalizing behaviors (β= -0.33, p = .04), and hyperactivity (β= -0.34, p = .05), compared to the low prenatal phthalate exposure group. There were no associations between the phthalate exposure groups and externalizing behaviors for boys.
Conclusion: Our study suggests that children’s exposure to phthalates prenatally may influence child behavior in a sex-specific manner. The use of mixture methods can help researchers understand the complex nature of co-occurring exposures and better inform public health on their impact on child behavior.

Authors

• Amanda Ramos, University of North Carolina at Chapel Hill
  Presenting Author

• Amy Herring, Duke University

• Stephanie M. Engel, University of North Carolina at Chapel Hill