Blood lead levels and calcium intake in Mexico City children under five years of age

Objective: The relationship between daily calcium intake and blood lead levels was evaluated among children under five years of age living in Mexico City. Methods: A random sample of 200 children under five years of age, resident in two neighborhoods of Mexico City was selected: Xalostoc, an industrial neighborhood, and Tlalpan, a residential neighborhood (100 from each area). The mothers of these children filled out a questionnaire on predictors of blood lead levels including daily calcium intake. Lead levels were determined from the venous blood samples. Calcium intake was assessed using a short Food Frequency Questionnaire including 11 food items that accounted for 95% of calcium intake in Mexico. Results: The average blood lead level was 9.93 mug dl(-1) (range 1-31 mug dl(-1)). An inverse relationship was observed between blood lead levels and daily calcium intake. This relationship was statistically significant among children aged 13 months - 5 years. Conclusion: The results suggest that calcium provided a protective effect against lead accumulation in the body among children. Further studies should be undertaken to evaluate this hypothesis through experimental design.