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

Abstract

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.