Data relating to prenatal lead exposure and child IQ at 4 and 8 years old in the Avon Longitudinal Study of Parents and Children

Abstract

As part of the Avon Longitudinal Study of Parents and Children (ALSPAC), measures of child IQ were collected by trained psychologists. The Wechsler Pre-school and Primary Scale of Intelligence – Revised UK edition (WPPSI) was used at age 4 years in a subsample of children enrolled in ALSPAC (the Children in Focus cohort), chosen at random from the last 6 months of ALSPAC births (about 10% of the participants). At age 8 years all children enrolled in the main cohort were invited to complete a short form of the Wechsler Intelligence Scale for Children (WISC)-III UK. Prenatal blood lead (B-Pb) concentrations were measured by inductively-couple plasma mass spectrometry in samples from women at a median gestation age of 11 weeks. Child blood lead was measured by atomic absorption spectrometry in samples from children attending the Children in Focus clinic at age 30 months. Maternal reports at 32 weeks’ gestation were used to generate data on a range of potential confounders. The data were used to determine the associations between prenatal exposure to lead and child IQ at 4 and 8 years. The effect of child B-Pb at 3 years as a moderator of these associations was tested. (For results, please see doi:10.1016/j.neuro.2017.07.003 Taylor et al., (2017)).

Sex-Dependent Effects of Developmental Lead Exposure on the Brain

“…Another study reported a significant interaction between level of prenatal Pb exposure and neuropsychological measures of attention and visuoconstruction abilities assessed in adolescence, with males (aged 15–17 years) performing worse than females ( Ris et al, 2004 ). A recent UK birth cohort study that investigated the association between prenatal Pb exposure (mean maternal blood Pb level 3.67 ± 1.46 μg/dL) and child IQ measured at 4 and 8 years of age showed maternal Pb exposure to have a greater effect on IQ in boys than in girls at age of 8 years or age, although the effect was statistically non-significant ( Taylor et al, 2017 ).…”

A Birth Cohort Study about the Genetic Modification of Prenatal Methylmercury Association with Child Cognitive Development

“…No substantial change in the association was observed after adjustment for maternal pregnancy selenium and vitamin D concentrations. Because fish intake is the main human source of methylmercury exposure (36), the low exposure levels might be a result of low-frequency fish intake in the ALSPAC cohort, in accord with the food habits of England’s general population (27). Studies on prenatal exposure to methylmercury have observed stronger adverse associations with mercury after statistically controlling for the opposing associations with fish intake and omega-3 fatty acids (8, 9, 13, 37).…”

“…The testers were trained psychologists who were overseen by a senior psychologist with long experience of psychometric testing within the study. She observed each tester, met with the group regularly to discuss the precise administration of each subtest, and checked their scoring (26, 27)…”

Prenatal lead, cadmium and mercury exposure and associations with motor skills at age 7 years in a UK observational birth cohort

“…Inductively-coupled plasma mass spectrometry in standard mode (R. Jones, Centers for Disease Control and Prevention (CDC), Bethesda, MD, USA; CDC Method 3009.1) was used to measure blood levels with appropriate quality controls ( Iles-Caven et al, 2016 ; Taylor et al, 2013 ; Taylor et al, 2017 ). The analyses were completed on samples from 4285 women for lead, 4286 women for cadmium and 4134 women for mercury.…”