Tracking source of contaminant lead in children’s blood as means for environmental remediation

Abstract:

Children are the most susceptible demographic affected by lead (Pb) poisoning due to increased hand-to-mouth interaction at early age. In this current project Pb isotope ratios are used for apportioning the sources of Pb in the blood of children (ages 1-6) screened for high blood Pb levels (>5μg/dL) surrounding urban areas of Kansas City, MO. We compared Pb isotope ratios measured in the child’s blood with those of the most likely sources of Pb in that child’s home environment. The environmental sources sampled consisted of soils, paints, occupational sources (e.g., oil rig workers’ uniforms, mechanics’ clothes), indoor air filters, and dusts. After collection, blood samples were decontaminated, digested in ultrapure nitric acid, filtered, and separated via ion chromatography (AG 1-X8) before analysis. Blood and environmental samples were analyzed for total Pb concentration, ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, and ²⁰⁸Pb/²⁰⁴Pb using the Neptune Plus multi-collector ICPMS. Differences in isotopic ranges in environmental samples from each household suggested that sources of Pb in both houses are different: ratios reflected in House 2 show a limited range while House 1 shows a larger range and greater heterogeneity in composition. By comparing the ²⁰⁸Pb/²⁰⁶Pb and ²⁰⁶Pb/²⁰⁷Pb ratios, we identified that the Pb in blood of the child from House 2 (²⁰⁸Pb/²⁰⁶Pb= 2.0101, ²⁰⁶Pb/²⁰⁷Pb= 1.2272) is isotopically similar to dusts by the door (²⁰⁸Pb/²⁰⁶Pb= 2.0108, ²⁰⁶Pb/²⁰⁷Pb= 1.2284) and soil from a roof drip zone (²⁰⁸Pb/²⁰⁶Pb= 2.0123, ²⁰⁶Pb/²⁰⁷Pb= 1.2262), indicating that the blood Pb level, in this case, may be influenced by both sources or their mixtures. Due to significant variations in isotopic ratios observed in House 1, we were only able to identify the source (dust from the kitchen baseboard, ²⁰⁸Pb/²⁰⁶Pb= 2.0237, ²⁰⁶Pb/²⁰⁷Pb= 1.2187) most isotopically similar to the blood (²⁰⁸Pb/²⁰⁶Pb= 2.0254, ²⁰⁶Pb/²⁰⁷Pb= 1.2132). It is not always possible to directly link the blood Pb to the environmental sources collected. However, when a link could be made, it was found that the Pb ratios of the child’s blood was most similar to the ratios of both outside soil and indoor dust from the home.