ASSOCIATIONS BETWEEN SOIL LEAD AND CHILDHOOD BLOOD LEAD IN URBAN NEW-ORLEANS AND RURAL LAFOURCHE PARISH OF LOUISIANA

This study evaluates associations between soil lead concentrations (SP b), age of housing, and blood lead levels (BPb) of children in metropo litan New Orleans and Lafourche Parish, Louisiana. The database includ es over 2,600 SPb and 6,000 BPb samples paired by their median values and pre-1940 housing percentages for 172 census tracts. Associations w ere evaluated with Fisher's exact test and Spearman's rho test and mod eled with the least sum of absolute deviations regression. Census trac ts with low SPb are associated with new housing, but census tracts wit h high SPb are evenly split between old and new housing [Fisher's exac t test, p = 8.60 x 10(-13) for the percentage of housing built before 1940 (percent pre-1940 housing) versus SPb]. The p-value for SPb versu s BPb is 12 orders of magnitude stronger than the p-value for percent pre-1940 housing versus BPb. Census tracts with low BPb are associated with new housing, but census tracts with high BPb are split evenly be tween old and new housing (Fisher's exact test, p = 1.67 x 10(-12) for percent pre-1940 housing versus BPb). Census tracts with high SPb are associated with high BPb and census tracts with low SPb are associate d with low BPb (Fisher's exact lest, p = 3.18 x 10(-24) for BPb versus SPb). The Spearman's rho test of the association of SPb and BPb in Or leans and Lafourche Parishes yielded a p-value of 6.12 x 10(-24). The least sum of absolute deviations regression model of the data is BPb = 1.845 + 0.7215 (SPb)(0.4). A comparison of the modeled BPb versus obs erved BPb has an r(2) of 0.552 and a p-value of 2.83 x 10(-23) that th is relation was due to chance. If blood lead in children is more close ly associated to soil lead than to the age of housing, then primary le ad prevention should also include soil lead.