Cadmium exposure and cognitive abilities and behavior at 10 years of age: A prospective cohort study

Background: We have previously reported inverse associations of prenatal and childhood cadmium exposure with cognition in 5-year-old Bangladeshi children. Objectives: To assess if cadmium exposure affected cognition and behavior in the Bangladeshi children at 10 years. Methods: Cadmium exposure was assessed by urinary concentrations at 10 (n = 1498) and 5 years of age (n = 1453), and of the mothers in early pregnancy (n = 1299), measured by ICP-MS. Cognitive abilities were assessed with Wechsler Intelligence Scale for Children (4th edition) and behavior with the parent-rated Strengths and Difficulties Questionnaire. Results: In multivariable-adjusted models, urinary cadmium at 10 years was inversely associated with Full scale IQ and most of the sub-scales. Associations were mainly observed in boys, in whom the difference in Full scale IQ was 7.0 scores (95% CI: -11, -2.7), corresponding to 0.21 SD, when comparing those in the highest (range: 0.30-2.6 mu g/L) and lowest tertile of urinary cadmium (0.036-0.18 mu g/L). Urinary cadmium at 5 years was inversely, but not significantly, associated with IQ. Children in the highest exposure tertile at 10 years also had poorer Prosocial behavior scores. The association appeared strongest in girls, in whom the corresponding OR for Prosocial scores in relation to cadmium exposure at 10 years and prenatally was 0.58 (95% CI: 0.34, 0.99) and 0.48 (95% CI: 0.25, 0.93), respectively. Conclusion: Childhood cadmium exposure was associated with lower intelligence in boys, and there were indications of altered behavior in girls for both prenatal and childhood exposures. Findings are of concern as similar exposure levels are common world-wide.