Exposure to metals during pregnancy and neuropsychological development at the age of 4 years

Abstract

Background: There is insufficient epidemiological evidence for deciding whether prenatal exposure to the current low-levels of metals in developed countries may affect neuropsychological function in early childhood.

Objectives: Our goal was to evaluate potential neurotoxic effects of prenatal exposure to seven metals (cobalt, copper, arsenic, cadmium, antimony, thallium and lead), during the 1st and 3rd trimester of pregnancy, on child neuropsychological development at 4 years of age.

Materials and methods: This study was based on a population-based birth cohort established in Sabadell (Catalonia, Spain) as part of the INMA [Environment and Childhood] Project. Metals were measured in 485 urine samples collected from mothers during the 1st and 3rd trimester of pregnancy. We assessed the neuropsychological development of 553 4-year-olds with the McCarthy Scales of Childrens' Abilitites (MSCA), together with their ADHD symptomatology, using the ADHD-DSM-IV criteria. A total of 385 children were included in the present study.

Results: We found no statistically significant associations between metals and general cognitive scale or executive function of the MSCA. We found negative coefficients for the exposure to cadmium 1st trimester, cadmium 3rd trimester and lead 3rd trimester on the general cognitive score of MSCA, although these results were not significant. We did not find any association between prenatal exposure to metals and ADHD symptomatology at the age of 4 years.

Conclusions: Our results do not suggest that prenatal exposure to current low-levels of metals impairs children's cognitive development during preschool years.

Keywords: 95% CI; 95% confidence interval; ADHD; ADHD Criteria of Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition form; ADHD-DSM-IV; Child development; Coef; Environmental exposure; HI; Heavy metals; IA; INMA; LOD; MSCA; McCarthy Scales of Children's Abilities; Nervous system; Neuropsychology; Q-ICP-MS; Revised Symptom Checklist; SCL-90-R; WAIS-III; Weschler Adult Intelligence-Third Edition; attention deficit and hyperactivity disorder; coefficient; environment and childhood project; hyperactivity/impulsivity scale; inattention scale; inductively coupled plasma quadruple mass spectrometry; limits of detection.