Persistent Effects of Maternal Prenatal Exposure to Phthalates on Child IQ at Age 7 Years

Abstract

Persistent Effects of Maternal Prenatal Exposure to Phthalates on Child IQ at Age 7 YearsAbstract Number:1756 Robin Whyatt, Beverly Insel, Antonia Calafat, Xinhua Liu, Rauh Virginia, and Pam Factor-Litvak* Robin Whyatt Mailman School of Public Health, Columbia University, United States, E-mail Address: [email protected] Search for more papers by this author , Beverly Insel Mailman School of Public Health, Columbia University, United States, E-mail Address: [email protected] Search for more papers by this author , Antonia Calafat Centers for Disease Control and Prevention, United States, E-mail Address: [email protected] Search for more papers by this author , Xinhua Liu Mailman School of Public Health, Columbia University, United States, E-mail Address: [email protected] Search for more papers by this author , Rauh Virginia Mailman School of Public Health, Columbia University, United States, E-mail Address: [email protected] Search for more papers by this author , and Pam Factor-Litvak* Mailman School of Public Health, Columbia University, United States, E-mail Address: [email protected] Search for more papers by this author AbstractBackground Prior research reports inverse associations between maternal prenatal urinary phthalate metabolite concentrations and mental and motor development in inner-city preschoolers. No study evaluated whether these associations persist into school age.Methods In a follow up study of n=328 inner-city mothers and their children, we measured metabolites of di-n-butyl phthalate (DnBP), butylbenzyl phthalate (BBzP), di-isobutyl phthalate (DiBP), di-2-ethylhexyl phthalate and diethyl phthalate in maternal prenatal urine. At child age 7 years, we administered the Wechsler Intelligence Scale for Children, 4th edition (WISC-IV), which measures four areas of cognitive function associated with overall intelligence quotient (IQ).Results Child full-scale IQ was inversely associated with prenatal urinary metabolite concentrations of DnBP and DiBP: b=-2.69 (95% confidence interval [CI] -4.33 to -1.05) and b= -2.69 (95% CI -4.22 to -1.16), respectively, for each log unit increase. Among children whose mothers had the highest versus lowest quartile concentration of DnBP and DiBP metabolites, IQ was 6.7 (95% CI 1.9 to 11.4), and 7.6 with (95% CI 3.2 to 12.1) points lower, respectively. Associations were unchanged after control for cognition at age 3 years. Significant inverse associations were also seen between maternal prenatal metabolite concentrations of DnBP and DiBP and child processing speed, perceptual reasoning and working memory; DiBP and child verbal comprehension; and BBzP and child perceptual reasoning. No other associations were found.Conclusion Maternal prenatal urinary metabolite concentrations of DnBP and DiBP, at levels within the ranges previously observed in the general population, are associated with deficits in children’s intellectual development at age 7 years. Because phthalate exposure is ubiquitous in the US and other developed countries, these results are of public health significance.