Estimating the Effects of Soil Remediation on Children's Blood Lead near a Former Lead Smelter in Omaha, Nebraska, USA

BACKGROUND: Lead exposures from legacy sources threaten children's health. Soil in Omaha, Nebraska was contaminated by emissions from a lead smelter and refinery. The U.S. Environmental Protection Agency excavated and replaced contaminated soil at the Omaha Lead Superfund Site between 1999 and 2016. OBJECTIVES: The goal of this study was to assess the association of soil lead level (SLL) and soil remediation status with blood lead levels (BLLs) in children living near or on the site. METHODS: We linked information on SLL at residential properties with children's BLLs and assigned remediation status to children's BLL measurements based on whether their measurements occurred during residence at remediated or unremediated properties. We examined the association of SLL and remediation status with elevated BLL (EBLL). We distinguished the roles of temporal trend and the intervention with time-by-interventionstatus interaction contrasts. All analyses estimated odds ratios (ORs) with a generalized estimating equations approach to ensure robustness under the complex correlations among BLL measurements. All analyses controlled for relevant covariates including children's characteristics. RESULTS: EBLL (>5 mu g/dL) was associated with both residential SLL [e.g., OR = 2.00; 95% confidence interval (CI): 1.83, 2.19; >400-800 vs. <= 200 ppm] and neighborhood SLL [e.g., OR = 1.85 (95% CI: 1.62, 2.11; >400-800 vs. <= 200 ppm)] before remediation but only with neighborhood SLL after remediation. The odds of EBLL were higher before remediation [OR 1.52 (95% CI: 1.34, 1.72)]. Similarly, EBLL was positively associated with preremediation status in our interaction analysis [interaction OR = 1.18 (95%CI: 1.02, 1.37)]. DISCUSSION: Residential and neighborhood SLLs were important predictors of EBLIA in children residing near or on this Superfund site. Neighborhood SLL remained a strong predictor following remediation. Our data analyses showed the benefit of soil remediation. Results from the interaction analyses should be interpreted cautiously due to imperfect correspondence of remediation times between remediation and comparison groups.