Nonlinear association between soil lead and blood lead of children in metropolitan New Orleans, Louisiana: 2000–2005

Abstract

Metropolitan New Orleans is unique because it has a universal blood lead (BL) screening dataset ( n = 55,551) from 2000–2005 spatially coupled with a soil lead (SL) dataset ( n = 5467) completed in 2000. We evaluated empirical associations between measurements of SL and BL exposure responses of children in New Orleans by stratifying the databases by Census Tracts and statistically analyzing them with permutation methods. A consistent curvilinear association occurred annually between SL and BL with robust significance ( P-values < 10 − 23 ). The mathematical model of the pooled BL datasets for 2000–2005 is: BL = 2.038 +0.172 × (SL) 0.5 (agreement ( ℜ) of 0.534, an r 2 of 0.528, and a P-value of 1.0 × 10 − 211 ) indicating that chance alone cannot explain the association. Below 100 mg/kg SL children's BL exposure response is steep (1.4 μg/dL per 100 mg/kg), while above 300 mg/kg SL the BL exposure response is gradual (0.32 μg/dL per 100 mg/kg). In 1995, the BL prevalence was 37% ≥ 10 μg/dL for the most vulnerable poor and predominantly African-American children. In the era of universal screening the prevalence of elevated BL is 11.8% ≥ 10 μg/dL for the general population of children. The SL map describes community variations of potential BL exposure. If health effects occur at BL ≥ 2 μg/dL, then 93.5% of the children in New Orleans are at risk. These results reinforce the proposal that prevention of childhood Pb exposure must include SL remediation as demonstrated by a New Orleans pilot project and a proactive Norwegian government program.