Association Between Lead Exposure and Red Blood Cell Folate Concentrations in U.S. Children Aged 2–17 Years: An Analysis of Data from NHANES 2007–2018

The objective of this study is to evaluate the impact of low blood lead levels (BLLs) on the red blood cell folate concentrations in U.S. children aged 2–17 years. All data were obtained from the National Health and Nutrition Examination Survey (NHANES) over six consecutive cycles from 2007–2008 to 2017–2018. A total of 12,739 children with BLLs lower than 10 µg/dL (geometric mean: 0.66 µg/dL) were included in the dataset. BLLs were categorized into three tertiles (tertile 1: <0.55 µg/dL; tertile 2: 0.55–0.95 µg/dL; and tertile 3: ≥0.95 µg/dL). The multivariate linear regression model analysis indicates a negative relationship between BLLs and red blood cell folate concentrations. After adjusting for potential confounding factors, red blood cell folate concentrations were lower in children in the BLL tertile 2 (β-coefficient = −0.0450; 95% CI: −0.0676, −0.0224) and BLL tertile 3 groups (β-coefficient = −0.0775; 95% CI: −0.1032, −0.0517) compared to children in the BLL tertile 1 group. When stratified by age, gender, and race/Hispanic origin, the subgroup analysis consistently revealed a negative relationship between BLLs and red blood cell folate concentrations, with red blood cell folate concentrations being lower (p < 0.05) in children in the BLL tertile 3 group compared to children in the tertile 1 group. Further investigation is needed to explore the mechanism underlying the potential relationship between BLLs and red blood cell folate concentrations and determine whether folate plays an active role beneficial for preventing the harmful effects of lead on children.