Effects of elevated blood lead levels in preschool children in urban Vellore.

OBJECTIVE To study the burden and associated risk factors for elevated blood lead levels among pre-school children (15-24 months) in urban Vellore, and to study its effects on child cognition and anemia. DESIGN An investigative study through Mal-ED cohort. SETTING Eight adjacent urban slums in Vellore, Tamil Nadu. PARTICIPANTS 251 babies recruited through Mal-ED Network. OUTCOME MEASURES Blood lead levels using Graphite Furnace Atomic Absorption Spectrophotometry method at 15 and 24 mo; hemoglobin estimation by azidemethemoglobin method; cognitive levels using Bayley Scales of Infant Development III. RESULTS Around 45% of children at 15 months and 46.4% at 24 months had elevated blood lead levels (>10 µg/dL). Among children who had elevated blood lead levels at 15 months, 69.2% (45/65) continued to have elevated levels at 24 months. After adjusting for potential confounders, children from houses having a piped drinking water supply and houses with mud or clay floors were at significantly higher risk of having elevated blood lead levels at 15 months. Thirty one percent (21/67) of the children with elevated blood lead levels had poor cognitive scores. Children with elevated blood lead levels at 15 months had higher risk (Adjusted OR 1.80; 95% CI 0.80 - 3.99) of having poorer cognitive scores at 24 months. More than half of the children (57%) were anemic at 15 months of age, and elevated blood lead levels were not significantly associated with anemia. CONCLUSIONS Elevated blood lead levels are common among preschool children living in urban slums of Vellore. Poorer conditions of the living environment are associated with elevated lead levels.