Prenatal and current phthalate exposure and cognitive development in 7-year-old children from the Odense child cohort

Abstract

BackgroundPhthalates are endocrine disrupters used in a variety of consumer products. Human studies suggest an association between phthalate exposure and cognitive development but adverse effects of the recently introduced phthalate substitutes have only been sparsely studied. ObjectivesTo investigate associations between prenatal and concurrent exposure to phthalates and IQ in 7-year-old children from the Odense Child Cohort. MethodsPregnant women from the Odense Child Cohort had phthalate metabolites measured in urine samples during 3rd trimester in 2010 to 2012. In addition, phthalates were also measured in urine samples from their offspring at age 7 years. IQ was assessed at age 7 years using four subtests from Wechsler Intelligence Scale for Children. The total study population consisted of 585 mother-child pairs with available prenatal urinary phthalate metabolites concentrations and IQ data at age 7 years. A subset of those (N = 274) had urinary phthalate metabolites measured in child urine at age 7 years. Phthalate concentrations were grouped into tertiles and associations with IQ were investigated using multiple linear regression adjusting for sex, maternal education and maternal/child BMI. ResultsUrinary phthalate metabolite concentrations both in pregnant women and children were generally lower compared to previous cohorts. Children with high prenatal urinary concentrations of MEP and metabolites of DEHP (∑DEHPm)(3rd tertile) had −3.1 (95% CI: −5.5, −0.6) (MEP) and − 3.0 (−5.5, −0.6) (∑DEHPm) IQ points at age 7 years compared to children with low concentrations (1st tertile). High concurrent urinary phthalate concentrations of MCPP, ∑DnHxPm, ∑DiDPm and ∑DiNPm in the 3rd tertile was associated with −3.7 (−7.2, −0.2), −4.4 (−7.9, −0.9), −3.7 (−7.2, −0.2) and − 5.6 (−9.1, −2.2) IQ points, respectively, compared to those with the lowest concentrations (1st tertile). ConclusionWe found significant inverse associations between some prenatal and concurrent urinary phthalate concentrations and IQ at age 7 years in this low exposed population. This suggests that exposure to phthalates both prenatally and during early childhood could be hazardous to child neurodevelopment, however, large-scale prospective studies assessing phthalate exposure through multiple urine samples, and possibly investigating cocktail effects of the chemicals as well as long term follow-up are warranted.