Prenatal phenolic compounds exposure and neurobehavioral development at 2 and 7years of age

Phenolic compounds such as bisphenol A (BPA), nonylphenol (NP), and octylphenol (OP) are known as endocrine-disrupting compounds and are commonly used. Their impacts on the neurodevelopment of children are inconclusive. The current study aims to investigate the association between umbilical cord blood levels of BPA, NP, OP and neurodevelopmental outcomes at 2 and 7years of age.

The study was based on the Taiwan Birth Panel Study, a prospective birth cohort. We collected cord blood plasma to measure phenolic compound levels using ultra-performance liquid chromatography-tandem mass spectrometry. In the follow-up, 208 mother-child pairs with 2-year-old children and 148 mother-child pairs with 7-year-old children were recruited in this study. We used the Comprehensive Developmental Inventory for Infants and Toddlers (CDIIT) and the Wechsler Intelligence Scale for Children (WISC-IV) for neurodevelopmental assessments at 2 and 7years of age, respectively. Multiple linear regressions were used for statistical analysis.

The detection rates of BPA, NP, and OP were 55.9%, 77.6%, and 68.3%, respectively. In this study, the median BPA, NP, and OP levels in 2-year-olds were 3.3, 72.6, and 3.3 (ng/ml), respectively. However, the median levels of BPA, NP, and OP were 3.2, 49.3, and 6.6 (ng/ml), respectively. The levels of phenolic compounds were log₁₀-transformed for statistical analysis. Gender stratification was performed. In the WISC-IV neurocognitive assessment, we found both a significant negative association and a trend between cord blood plasma BPA levels and full-scale IQ (p for trend<0.01), the verbal comprehension index (p for trend<0.01), and the perceptual reasoning index (p for trend<0.01) in the study population. After stratification by sex, significant associations were found in full-scale IQ (p for trend=0.03) and the verbal comprehension (p for trend<0.01) index in boys. In girls, prenatal BPA exposure had adverse effects on full-scale IQ (p for trend=0.02), perceptual reasoning index (p for trend<0.01), and working memory index (p for trend=0.02). None of the developmental quotients (DQs) of the CDIIT analysis were significantly associated with phenolic compound levels in cord blood based on continuous or categorical measures.

Prenatal exposure to BPA affects neurocognitive development, and this effect differs between 7-year-old boys and girls. More studies are needed to elucidate the relationship between phenolic compound exposure in utero and children's neurobehavioral development.