Exposures to Contemporary and Emerging Chemicals among Children Aged 2 to 4 Years in the United States Environmental Influences on the Child Health Outcome (ECHO) Cohort.

Prenatal and early life exposure to environmental chemicals can increase the risk of multiple adverse child health outcomes. However, biomonitoring data for young children remain limited. This study leveraged the nationwide Environmental influences on Child Health Outcomes (ECHO) Cohort to assess chemical exposures in 201 children aged 2-4 years between 2010 and 2021. A total of 111 analytes across multiple chemical classes were simultaneously quantified in single spot urine specimens collected from each child and their mother during pregnancy, and concentrations were compared between child and prenatal maternal samples. Among the 111 analytes, 96 were detected in at least five children and 48 analytes in over 50% of children. Thirty-four were ubiquitously detected (>90%), nine of which have not been included in U.S. national biomonitoring: benzophenone-1, triethyl phosphate, and metabolites of six phthalates and one alternative plasticizer. Concentrations of bisphenol S, three pesticide biomarkers, and two phthalate biomarkers were higher in children than in mothers, while those of triclosan and monoethyl phthalate were higher in mothers. This study reveals frequent exposure to multiple chemicals in young U.S. children, often exceeding prenatal levels. Expanded biomonitoring of emerging chemicals of concern and studies of their health effects in this vulnerable population are warranted.