Racial disparities in children’s blood lead levels: Possible implication of divalent metal transporter 1

Abstract

Adverse effects of lead exposure at low-dose (<10μg/dL) in children showed a growing interest over the last decades. Black ethnicity is usually associated with elevated blood lead levels (BLLs), independently of age and socioeconomic conditions. The gastrointestinal uptake of lead represents a key step in the process of lead kinetic and toxicity. The involvement of divalent metal transporter 1 (DMT1) in the lead absorption has been previously presumed and reported. I postulate that inter-ethnic differences in DMT1 expression may explain a large part of the racial disparity in children’s BLLs, and suggest a few analyses to test this hypothesis. The hypothesis rests on some observations from previous researches. The inverse association between BLLs and iron intake has been reported in both cross-sectional and follow-up studies. It appears that no study specifically addressed the modifying effect of ethnicity in this association. Previous reports suggest that DMT1 is the primary mechanism for gastrointestinal iron absorption. There are four forms of DMT1 expressed in the enterocytes, which did not respond similarly to iron changes. It is not excluded that some children be more likely to uptake ingested lead depending on DMT1 isoform expressed. I hypothesize that the expression of the more active DMT1 isoform (+1A/+IRE) is more common in Non-Hispanic Black compared with Non-Hispanic White children, and I suggest how to test this hypothesis. If the hypothesis is confirmed, this would suggest that the prevention of iron-deficiency must be included in the primary programs for preventing increase of BLLs in Non-Hispanic Black children, rather than as part of secondary prevention. Moreover, thorough studies would be useful to characterize the interaction between environmental lead levels and DMT1 expression in relation to BLLs in young children.