Lead and essential trace element levels in school children: A cross-sectional study

BACKGROUND: Nutritional status is thought to modulate susceptibility to lead (Pb) toxicity. The type and nature of these interactions needs to be investigated. AIM: To assess the prevalence of sub-clinical Pb toxicity (defined by ≥ 10 μ_rm;g/dL blood levels) and trace element deficiencies (Iron (Fe), Zinc (Zn), Copper (Cu) and Magnesium (Mg)) and to find out their possible relationship, if any. SUBJECTS AND METHODS: A cross-sectional survey was carried out in a total of 195 school children residing in urban (n = 65), urban heavy traffic (n = 65) and urban industrial (n = 65) zones of Hyderabad, India. Blood Pb, trace element levels, haemoglobin and δ-aminolevulinate dehydratase (δ-ALAD) activity was measured. RESULTS: High blood lead levels ( ≥ 10 μ_rm;g/dL) were observed in 54.3% of children while percentage prevalence of trace element deficiencies such as Fe (16.2%), Zn (68.6%), Mg (41.7%) and Cu (25%) were also high in children included in the study. Higher blood Pb levels and reduced δ-ALAD activity was observed in children residing in heavy traffic and industrial areas. Blood Pb levels but not δ-ALAD activity correlated inversely with serum Fe in heavy traffic and industrial children, respectively. Interestingly, δ-ALAD activity but not blood Pb levels correlated inversely with trace element levels only in urban children. CONCLUSIONS: These results suggest higher prevalence of sub-clinical Pb toxicity and trace element deficiencies in urban children. Further, high blood Pb levels appear to be correlated with reduced δ-ALAD activity and iron status in Pb exposed children.