Gender differences in trace element exposures with cognitive abilities of school-aged children: a cohort study in Wujiang city, China

Abstract

Trace elements persist in the environment, and their early exposure may adversely affect children's intellectual development. To clarify the influence of blood trace element levels in newborns and school-aged children, we used Wechsler Intelligence Scale for children (WISC-CR) to explore intellectual development level of 148 school-aged children based on a population cohort study. Lead (Pb), selenium (Se), arsenic (As), copper (Cu), manganese (Mn) and chromium (Cr) in cord blood and Pb, As, Cu in venous blood were determined by inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometer (AAS). Our analysis of the correlation between children's mental development and trace element content found children's cognitive abilities negatively correlate with Pb (PIQ: β=-0.109, P=0.03737) and Cu (PIQ: β=-0.031, P=0.04431; FISQ: β=-0.031, P=0.02137) levels in cord blood. Prenatal low-level As exposure may negatively affect girls' performance intelligence quotient (PIQ) and verbal intelligence quotient (VIQ). There were differences in Se levels in cord blood and venous blood between boys and girls (P=0.010; P=0.073). High Se levels were associated with a lower VIQ in boys and a higher VIQ in girls. Prenatal exposure to Pb, As and Cu may weaken children's cognitive abilities at school age. Se exposure may have opposite effects on cognitive abilities affected by dose and gender.

Keywords: Cognitive abilities; Early childhood exposure; Gender difference; Trace elements.