The urban environment and children's health: Soils as an integrator of lead, zinc, and cadmium in New Orleans, Louisiana, USA

Soils are evaluated as a diagnostic tool of environmental conditions that i nfluence health. The samples for this study are urban topsoil (0-2.5 cm dep th) samples (n = 4026) analyzed for Pb, Zn, and Cd by inductively coupled p lasma-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. Th e urban samples were stratified by census tract (n = 286). Blood Pb (BL) le vels of children less than or equal to 6 years were also stratified by cens us tract and paired with soil Pb (SL) (n = 175). A significant association (P = 1.2 x 10(-23)) was found between median BL and median SL. The associat ion 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 = 3.5 x 10(-22)). A med ian SL threshold (greater than or equal to 310 mu g g(-1) and <310 mu g g(- 1)) for higher metal census tracts (HMCTs) and lower metal census tracts (L MCTs), respectively, represents median BL exposures above and below 9 mu g dL(-1). HMCTs and LMCTs were characterized by demographic and socioeconomic data. HMCTs are more likely (P = 4.5 x 10(-6)) inhabited by Blacks than by Whites. Of 13,803 children less than or equal to 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 indicat ors 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 mu g g (-1), and empirically, a safe SL for most children is around 80 mu g g(-1). SL is a useful diagnostic tool, and curtailing SL may complement primary P b prevention for children. (C) 1999 Academic Press.