REMEDIATING SOIL PB CONTAMINATION, ADDRESSING A SERIOUS HEALTH RISK, SOUTHWEST DETROIT, MICHIGAN USA

The Delray community of southwest Detroit is one of the most depressed areas in southeast Michigan. Surrounded by industry, this residential community suffered from decades of industrial waste discharges that have left Delray with extensive air and soil pollution. Although high unemployment and poverty are major challenges confronting residents in Delray today, the risk of public health problems from Pb, Hg, As and Cr [VI] in the soil may become an even bigger issue and a significant source of concern. Newspaper headlines cite crime, substance abuse, high school and labor force dropout, as being prevalent in Delray, but recent research suggest that soil contamination, which has resulted in elevated blood Pb levels may be an underlying factor. Young children injest the soil while playing in their yards by hand-to-mouth activities, leading to elevated blood-lead levels. In urban areas such as southwest Detroit, the sources of Pb are numerous, ranging from Pb-based paints on homes to brownfield sites that include former Pb-smelting operations to active industrial discharges. Bench studies and a recently completed pilot study however, have demonstrated that stabilization (immobilization) techniques, designed to decrease the leachable or bioaccessible Pb by adding amendments to the soil, can provide a cost-effective solutions for communities or neighborhoods with wide spread soil Pb contamination. In the pilot study in a section of Delray, where the total Pb exceeds 400 mg/Kg, the bioaccessible lead is >350 mg/Kg. By adding the phosphate-based fertilizer to the soil, the bioaccessible Pb in the soil was reduced by 80% to 71 mg/Kg. Although the total Pb (>400 mg/Kg) remains the same, the Pb available for human uptake was substantially reduced. These results show that blood lead poisoning among young children (age 2-6), which still remains prevalent in many urban areas can be reduced significantly under the right circumstances.