Soils are evaluated as a diagnostic tool of environmental conditions that in£uence health. The samples for this study are urban topsoil (0^2.5 cm depth) samples (n = 4026) analyzed for Pb, Zn, and Cd by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The parent materials for New Orleans soils are derived from the Mississippi River, and alluvium from the Bonnet Carre¨Spillway (n = 31) serve as control samples for this study. The urban samples were strati¢ed by census tract (n = 286). Blood Pb (BL) levels of children 6 years were also strati¢ed by census tract and paired with soil Pb (SL) (n = 175). A signi¢cant association (P = 1.26 610 723 ) was found between median BL and median SL. The association was modeled by BL = 3.06+0.33 (SL) 0.5 (correlation coe¤cient = 0.69 between the modeled BL and the observed BL and P = 3.56 610 722 ). A median SL threshold (310 m mg g 7 71 and 5310 m mg g 7
71
) for higher metal census tracts (HMCTs) and lower metal census tracts (LMCTs), respectively, represents median BL exposures above and below 9 m mg dL 71 . HMCTs and LMCTs were characterized by demographic and socioeconomic data. HMCTs are more likely (P = 4.56 610 7
76
) inhabited by Blacks than by Whites. Of 13,803 children 6 years in HMCTs, 75% are Black and 22% are White, with other making up the remaining 3%. In LMCTs, the Black to White children ratio is 50:50. In HMCTs, socioeconomic indicators for Blacks are depressed compared to Whites. Zn and Cd are potentially phytotoxic in HMCTs. Children exhibit a steep rise in BL at SL 5100 m mg g 71 , and empirically, a safe SL for most children is around 80 m mg g 71 . SL is a useful diagnostic tool, and curtailing SL may complement primary Pb prevention for children.