Childhood blood lead levels and intellectual development after ban of leaded gasoline in Taiwan: A 9-year prospective study

Background: Lead (Pb) exposure is associated with children's neurodevelopment, even at low doses. Leaded gasoline was banned in Taiwan in 2000 to reduce environmental exposure to Pb. Objectives: To evaluate the neurodevelopmental effect of low-level Pb exposure in young children. Methods: In 2001-2002, we have recruited 430 pregnant women in the third-trimester in Taichung, Taiwan who answered detailed questionnaires in the obstetric clinic. A total of 119, 76, and 66 children were followed up at 2-3, 5-6 and 8-9. years, respectively. We collected blood samples from pregnant women, Umbilical cord and children, and evaluated children's neurodevelopment and cognition function at all three time points using Bayley and Wechsler tests. Blood samples were analyzed for whole blood lead (BPb) levels. Results: Geometric mean of BPb in pregnant women, cord blood and children at 2-3, 5-6 and 8-9. years old were 2.21, 1.30, 2.48, 2.49 and 1.97μg/dl, respectively. Low-level postnatal Ln BPb was significantly associated with not only decreasing intelligence quotient (IQ), but also delayed cognitive function in children at 5-8. years (β: - 5.97, SE: 2.59, p = 0.025), after adjustment for maternal education, maternal BPb exposure, Home Observation for Measurement of the Environment Inventory (HOME), and gender of child, using linear mixed models. No significant relation was observed between prenatal and cord blood Pb levels and children's cognitive function in children 2-8. years. Conclusions: Low-level postnatal BPb levels in children at 2-5. years may have lagged effects on neurodevelopment in those at 5 to 8. years. Action is warranted to reduce even very low environmental Pb levels to reduce the developmental burden of Pb on children.