Tracking the Source of High Lead in Children's Blood

Children are the most susceptible demographic affected by lead (Pb) poisoning because of increased hand-to-mouth interaction at an early age. Here, 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 (>5 g/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, dusts, and dietary sources (e.g., spices). 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 ICP-MS. The average lead levels (BLL) measured in the blood aliquots were 12.7 μg/dL, 3.5 μg/dL, and 2.9 μg/dL, for Houses 1, 2 and 3, respectively. Pb isotope ratios from House 2 show a limited range, while House 1 and House 3 show heterogeneous compositions. By comparing the 208Pb/206Pb and 206Pb/207Pb isotope ratios, we identify that the Pb in blood of the child from House 2 (208Pb/206Pb= 2.010, 206Pb/207Pb= 1.227, respectively) is isotopically similar to dust by the door (208Pb/206Pb= 2.011, 206Pb/207Pb= 1.228) and soil from a roof drip zone (208Pb/206Pb= 2.012, 206Pb/207Pb= 1.226), indicating that the blood Pb level, in this case, may be influenced by both sources or their mixtures. In House 1, there was one environmental source (dust from the kitchen baseboard, 208Pb/206Pb= 2.024, 206Pb/207Pb= 1.219) that was most similar isotopically to the blood (208Pb/206Pb= 2.025, 206Pb/207Pb= 1.213). Although the range in the Pb isotope ratios of environmental samples in House 3 was large, we determined that the Pb isotope ratios of a sample of turmeric cooking spice (208Pb/206Pb= 2.131, 206Pb/207Pb= 1.128) to be remarkably similar to the blood (208Pb/206Pb= 2.132, 206Pb/207Pb= 1.127), suggesting a direct link, through the ingestion of the spice, to the elevated BLL