Blood Cadmium is Elevated in Iron Deficient U.S. Children

Abstract

Background- Iron deficiency (ID), lead (Pb) and cadmium (Cd) are known risk factors for neurodevelopmental disorders in infants and children. However, studies assessing cumulative effects of these factors together are lacking, especially in children. One concern, among others, regarding cumulative effects is for increased uptake of heavy metals in the presence of ID. Aim- Determine if blood Cd, urinary Cd and blood Pb levels are elevated in ID children compared to non-ID children. Methods- Blood and urinary Cd, blood Pb, and iron indicators from 5485 children, aged 3-19 years, were obtained from the 1999-2002 National Health and Nutrition Examination Surveys. ID was assigned if >=2 of 3 abnormal indicators (ferritin [FTN], % transferrin saturation [TFSAT], erythrocyte protoporphyrin [EPP]) were present. Linear regression was used to evaluate the relationships between iron status and blood Cd, urinary Cd (n=1508) and blood Pb, adjusted for gender, age, race/ethnicity, poverty and cotinine. Results- Prevalence of ID was 7.4% and 29.2% of children had >=1 abnormal iron indicator. Odds of ID increased with blood Cd (medium & high vs. <LOD), adjusted ORs=1.7 [95%CI: 1.4-2.2] & 2.6 [1.8-3.7], p-trend<0.0001. Odds of ID were also positively (though not as strongly) associated with urinary Cd, and negatively associated with blood Pb, though neither was statistically significant after adjustment for covariates. Continuous iron indicators yielded similar trends: FTN inversely associated with blood/urinary Cd and positively associated with blood Pb; TFSAT inversely associated with blood Cd and positively associated with blood Pb; EPP positively associated with urinary Cd and inversely associated with blood Pb. Conclusions- Current ID was associated with blood Cd, a biomarker of recent Cd exposure. Given their shared neurotoxic effects, and that many children live in areas with high burdens of both ID and heavy metals, research into these nutrient-toxicant interactions is vital.