Associations Between Maternal Prenatal Phthalate Urinary Metabolite Concentrations and Child Mental and Motor Development at Age 3 Years

Abstract

O-30C7-1 Background/Aims: Recent epidemiologic research has shown inverse associations between prenatal and postnatal phthalate urinary metabolite concentrations and child IQ and executive function. Methods: We have evaluated relationships between maternal prenatal urinary metabolite concentrations and child age 3 Mental Development Index (MDI) and Psychomotor Development Index (PDI) on the Bayley Scales of Infant Development II among 315 mothers and children in New York City. Metabolites were mono-n-butyl phthalate (MnBP), mono-benzyl phthalate, monoisobutyl phthalate (MiBP), and 4 di-2-ethylhexyl phthalate (DEHP) metabolites: mono-2-ethylhexyl phthalate (MEHP), mono-2-ethyl-5-hydroxyhexyl phthalate, mono-2-ethyl-5-oxohexyl phthalate, and mono-2-ethyl-5-carboxypentyl phthalate (MECPP). Concentrations were adjusted for specific gravity and log-transformed. Models controlled for race/ethnicity, child gender, gestational age, maternal education, material hardship, prenatal environmental tobacco smoke, and quality of the home environment. Chlorpyrifos levels were low with little variability. Prenatal polycyclic aromatic hydrocarbons did not improve model fit. Thus, neither was included in the models. Results: None of the metabolites were significantly associated with child MDI. However, MEHP/sum of the 4 DEHP metabolites × 100 (%MEHP, thought to be a biomarker of susceptibility) was inversely associated with MDI (B = −0.22; 95% CI: 01, −0.46; P = 0.06). Child PDI scores decreased with increasing concentrations of (ln)MnBP (B = −2.4; 95% CI: −0.7, −4.1; P = 0.007) and (ln)MiBP (B = −2.0; 95% CI: −0.4, −3.6; P = 0.01) and the odds ratio for risk of motor delay increased significantly (1.5; 95% CI: 1.0, 2.2; P = 0.04 and 1.8; 95% CI: 1.2, 2.6; P = 0.004 for (ln)MnBP and (ln)MiBP). In contrast (ln) MECPP was positively associated with child PDI scores (B = 1.9; 95% CI: 0.4, 3.5; P = 0.01) but did not modulate risk of motor delay (P = 0.5). Conclusion: Prenatal exposure to some phthalates may modulate child development. However, these are among the first reports of effects on mental and motor development and should be interpreted with caution. Additional research is warranted to explore these hypotheses.