Soils are evaluated as a diagnostic tool of environmental conditions that influence 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 Carré Spillway (n=31) serve as control samples for this study. The urban samples were stratified by census tract (n=286). Blood Pb (BL) levels of children </=6 years were also stratified by census tract and paired with soil Pb (SL) (n=175). A significant association (P=1.2x10(-23)) was found between median BL and median SL. The association was modeled by BL=3.06+0.33 (SL)(0.5) (correlation coefficient=0.69 between the modeled BL and the observed BL and P=3.5x10(-22)). A median SL threshold (>/=310 microgram g(-1) and <310 microgram g(-1)) for higher metal census tracts (HMCTs) and lower metal census tracts (LMCTs), respectively, represents median BL exposures above and below 9 microgram dL(-1). HMCTs and LMCTs were characterized by demographic and socioeconomic data. HMCTs are more likely (P=4. 5x10(-6)) 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 <100 microgram g(-1), and empirically, a safe SL for most children is around 80 microgram++ g(-1). SL is a useful diagnostic tool, and curtailing SL may complement primary Pb prevention for children.
Copyright 1999 Academic Press.