GEOGUIDELINES FOR URBAN AREAS: THE NEED FOR CLEAN SOIL POLICIES TO PROTECT US CHILDREN LIVING IN URBANIZED AREAS

This presentation is on children’s response to lead (Pb) contaminated urban environments and policies needed to prevent continuing exposure. The median US background soil Pb is 16.5 mg/kg (range 10.3 to 30.1 mg/kg), and quantities of soil Pb within major urbanized areas (UAs) are at least an order of magnitude larger. Two major Pb products, Pb-based paint and additives in gasoline contaminated UAs. The masses of gasoline Pb additives are consistently underreported. The 1950 through 1982 fuel sales by state accounts for ~1.4 million metric tons (MT) Pb of the US total of 4.6 million MT during the same years. Aerosol inputs into the 90 UAs from gasoline Pb additives range from 100’s to more than 100,000 MT of Pb depending on traffic flows. Soils became both a sink and a source of urban Pb dust.

The response of children to urban soil Pb contamination in New Orleans serves as a case example. The maximum of ~1811 MT lead (Pb) in exterior paint on 86,000 New Orleans houses, compares with ~12,000 MT from vehicle exhaust yielding ~ 9100 MT Pb; ~4850 MT were particles >10 µm and ~4200 MT were <0.25 µm. Brick public properties in the inner city had significantly more soil Pb contamination and higher prevalence of elevated children’s blood Pb than same-aged brick public properties in the outlying urban areas. The median concentration of Pb dust in the inner-city soil was 438 mg/kg or 3.7 times larger than Pb dust in outlying area median soil Pb of 117 mg/kg (p-value = 2.9 × 10^-15). The prevalence of children’s blood Pb ≥ 10µg/dL was 22.9% within the inner-city and 9.1% in the outlying areas of New Orleans (p-value = 3.4 × 10^-74).

Lead dust from gasoline additives are a plausible explanation for the differences in soil Pb and children’s blood Pb within the higher traffic congested inner-city core compared with the lower traffic congested outer areas of New Orleans. Although varied in quantity because of city size, similar patterns of environmental Pb dust contamination and childhood Pb exposure are expected for all US cities. To meet the goal of primary childhood Pb exposure prevention, the findings underscore the need, similar to the national clean air act or the clean water act, for clean soil policies to counteract the impact on the health and well-being of children of the Pb dust from gasoline additives and paint sources that have accumulated in urban soils.