New Orleans before and after Hurricanes Katrina/Rita: a quasi-experiment of the association between soil lead and children's blood lead.

Prior to Hurricanes Katrina and Rita (HKR), significant associations were noted between soil lead (SL) and blood lead (BL) in New Orleans. Engineering failure of New Orleans levees and canal walls after HKR set the stage for a quasi-experiment to evaluate BL responses by 13 306 children to reductions in SL. High density soil surveying conducted in 46 census tracts before HKR was repeated after the flood. Paired t test results show that SL decreased from 328.54 to 203.33 mg/kg post-HKR (t = 3.296, p < or = 0.01). Decreases in SL are associated with declines in children's BL response (r = 0.308, p < or = 0.05). When SL decreased at least 1%, median children's BL declined 1.55 microg/dL. Declines in median BL are largest in census tracts with > or =50% decrease in SL. Also individual BL in children was predicted as a function of SL, adjusting for age, year of observation, and depth of flood waters. At the individual scale, BL decreased significantly in post-HKR as a function of SL, with BL decreases ranging from b = -1.20 to -1.65 microg/dL, depending on the decline of SL and whether children were born in the post-HKR period. Our results support policy to improve soil conditions for children.