Iron deficiency associated with higher blood lead in children living in contaminated environments

The evidence that iron deficiency increases lead child exposure is based pr imarily on animal data and limited human studies, and some of this evidence is contradictory. No studies of iron status and blood lead levels in child ren have accounted for environmental lead contamination and, therefore, the source of their exposure. Thus, no studies have directly determined whethe r iron deficiency modifies the relationship of environmental lead and blood lead. In this study, we compared blood lead levels of iron-deficient and i ron-replete children living in low, medium, or highly contaminated environm ents. Measurements of lead in paint, soil, dust, and blood, age of housing, and iron status were collected from 319 children ages 1-5. We developed tw o lead exposure factors to summarize the correlated exposure variables: Fac tor 1 summarized all environmental measures, and Factor 2 was weighted for lead loading of house dust. The geometric mean blood lead level was 4.9 mug /dL; 14% exceeded 10 mug/dL. Many of the children were iron deficient (24% with ferritin < 12 ng/dL). Seventeen percent of soil leads exceeded 500 mug /g, and 23% and 63% of interior and exterior paint samples exceeded 5,000 m ug/g. The unadjusted geometric mean blood lead level for iron-deficient chi ldren was higher by 1 mug/dL; this difference was greater (1.8 mug/dL) afte r excluding Asians. Blood lead levels were higher for iron-deficient childr en for each tertile of exposure as estimated by Factors 1 and 2 for non-Asi an children. Elevated blood lead among iron-deficient children persisted af ter adjusting for potential confounders by multivariate regression; the lar gest difference in blood lead levels between iron-deficient and -replete ch ildren, approximately 3 mug/dL, was among those living in the most contamin ated environments. Asian children had a paradoxical association of sufficie nt iron status and higher blood lead level, which warrants further investig ation. Improving iron status, along with reducing exposures, may help reduc e blood lead levels among most children, especially those living in the mos t contaminated environments.