Identifying Vulnerable Neurodevelopment Windows of Triclosan Exposure in Children

Abstract

Background/Aim: Exposure to triclosan, an endocrine disrupting chemical, may decrease circulating thyroxine levels or interfere with thyroid hormone signaling during gestation or early childhood neurodevelopment. In this study, we investigated associations of prenatal and postnatal triclosan exposure with intellectual abilities among 199 children in the HOME Study birth cohort. Methods: We quantified triclosan in up to three maternal urine samples collected during the second and third trimesters and within 48 hours of delivery. We also quantified triclosan in child urine samples collected up to six times between 1 and 8 years of age. At age 8 years, children’s full scale IQ (FSIQ) was assessed using the Wechsler Intelligence Scale for children, 4th Edition (WISC-IV). We applied a multiple informant method to account for repeated triclosan measurements from the same individual at different visits, estimate covariate-adjusted triclosan-IQ associations at each visit, and test if triclosan-IQ associations at each visit differed from one another. Results: Maternal triclosan concentrations during pregnancy were not associated with FSIQ scores. However, for each 10-fold increase in triclosan concentration at delivery, there was a 4.1-point decrease in child full scale IQ (95% CI: -6.5, -1.7) at age 8 years. Children’s triclosan concentrations were not associated with FSIQ scores. The interaction p-value between triclosan and visit suggested that the association between repeated triclosan concentrations and child IQ varied by exposure timing (p-value=0.05). The pattern of associations between repeated triclosan concentration and child IQ was not modified by sex (p > 0.44). Conclusions: Triclosan concentration at birth, but not at other exposure windows, was inversely associated with child IQ at age 8 years, suggesting a heightened window of vulnerability to triclosan exposure around delivery for children in this cohort. This association suggests a possible window of vulnerability that warrants further investigation.