Associations of Blood Lead Concentrations with Ferritin, Vitamin B12, and Homocysteine Levels in Mexican Preschool Children: A Nationally Representative Study.

Lead exposure remains a significant public health concern in Mexico. Preschool children are particularly susceptible to lead toxicity, and alterations in micronutrient status, including iron, have been linked to lead exposure. However, data on the association between blood lead concentration and micronutrient status in Mexican preschool children are lacking. In this study, data from the 2022 National Health and Nutrition Survey (Encuesta Nacional de Salud y Nutrición, ENSANUT) were analyzed. The associations between blood lead concentration and biochemical parameters (ferritin, soluble transferrin receptor, vitamin B12, homocysteine, folate, and C-reactive protein) were evaluated using 249 samples, representing 1,864,366 Mexican preschool children. The potential mediating role of vitamin D was also examined. Generalized linear models were applied. Each unit increase in blood lead concentration was associated with a 5% reduction in ferritin and vitamin B12 levels (p < 0.001). Blood lead concentration was also positively associated with homocysteine levels (1.5%; p < 0.001). Vitamin D did not mediate the association between blood lead concentration and biochemical parameters. These findings indicate that elevated blood lead levels are associated with changes in micronutrient status among Mexican preschool children.