Nonlinear associations between blood lead in children, age of child, and quantity of soil lead in metropolitan New Orleans

Previous studies identified a curvilinear association between aggregated blood lead (BL) and soil lead (SL) data in New Orleans census tracts. In this study we investigate the relationships between SL (mg/kg), age of child, and BL (μg/dL) of 55,551 children in 280 census tracts in metropolitan New Orleans, 2000 to 2005. Analyses include random effects regression models predicting BL levels of children (μg/dL) and random effects logistic regression models predicting the odds of BL in children exceeding 15, 10, 7, 5, and 3 μg/dL as a function of age and SL exposure. Economic benefits of SL reduction scenarios are estimated. A unit raise in median SL0.5 significantly increases the BL level in children (b = 0.214 p = < 0.01), and a unit change in Age0.5 significantly increases child BL (b = 0.401, p = < 0.01). A unit change in Age0.5 increases the odds of a child BL exceeding 10 μg/dL by a multiplicative factor of 1.23 (95% CI 1.21 to 1.25), and a unit (mg/kg) addition of SL increases the odds of child BL > 10 μg/dL by a factor of 1.13 (95% CI 1.12 to 1.14). Extrapolating from regression results, we find that a shift in SL regulatory standard from 400 to 100 mg/kg provides each child with an economic benefit ranging from $4710 to $12,624 ($US 2000). Children's BL is a curvilinear function of both age and level of exposure to neighborhood SL. Therefore, a change in SL regulatory standard from 400 to 100 mg/kg provides children with substantial economic benefit.

Research Highlights
► New Orleans studies identified a curvilinear association between soil Pb and blood Pb.
► Random effects regression models predict odds for children exceeding various BLLs.
► Increased soil Pb and children's age directly and significantly increase blood Pb.
► Shift of soil Pb from 400 to 100 mg/kg has per child gains of $4.7k–$12.6k.
► A 400 to 100 mg soil Pb regulatory change is linked with large economic benefits.