The relationship between pregnancy phthalate exposure and language development at 2 years of age

Abstract

BACKGROUND AND AIM: Phthalates are endocrine disrupting chemicals found in many consumer products. Pregnancy exposure has been associated with adverse neurodevelopmental outcomes, but few studies have examined their association with language development. Even less is known about replacements for commonly used phthalates. METHODS: The MacArthur-Bates Communicative Development Inventories (CDI) was used to evaluate language development in 300 2-year-old children (average age of 27 months; 149 males, 151 females) in the Illinois Kids Development Study. Phthalate metabolites were quantified in a pool of five maternal urine samples collected across pregnancy. Associations of monoethyl phthalate (MEP) and the sums of metabolites of di(2-ethylhexyl) phthalate (ΣDEHP), di(isononyl) phthalate (ΣDINP), antiandrogenic phthalates (ΣAA), and di(2-ethylhexyl) terephthalate (ΣDEHTP) with each CDI outcome were assessed using generalized linear models. Models were adjusted for child age and sex, delivery type, and maternal age, education, verbal IQ, and parity. RESULTS: Most mothers were white, non-Hispanic, college educated, approximately 30 years old, and gave birth vaginally. Most children were firstborn. All phthalate exposure biomarkers were associated with changes in vocabulary scores. MEP and ΣDEHTP were also associated with the mean of the three longest utterances (M3L) and with language complexity scores. MEP and ΣDEHTP were both associated with lower vocabulary scores (MEP β=-12.16,95%CI:-21.15,-3.17; ΣDEHTP β=-21.09,95%CI:-38.83,-3.36), M3L scores (MEP β=-0.12,95%CI:-0.25,0.02; ΣDEHTP β=-0.28,95%CI:-0.54,-0.02), and complexity scores (MEP β=-0.67,95%CI:-1.33,-0.02; ΣDEHTP β=-1.15,95%CI:-2.45,0.16). Associations of other biomarkers with vocabulary were specific to male children. ΣAA (β=-31.86,95%CI:-67.47,3.74) and ΣDEHP (β=-19.89,95%CI:-41.96,2.18) were associated with lower vocabulary scores in males while ΣDINP (β=12.50,95%CI:0.63,24.36) was associated with higher vocabulary scores in males. CONCLUSIONS: Pregnancy exposure to some phthalates, particularly DEP and DEHTP, a replacement for DEHP, may be related to poorer language outcomes at 2 years of age, especially in male children. KEYWORDS: language development, phthalates, neurodevelopment