Lead guidelines for children’s play areas: The need for clean soil policies to protect children

Children’s empirical response to lead (Pb) in soil and revised policy needs are discussed. The median US background soil Pb is 16.5 mg/kg (range 10.3 to 30.1 ppm), and soils of urbanized areas (UAs) are often 500-1000 ppm or more. Two Pb products, Pb-based paint and additives in gasoline contaminated UAs, and 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 in 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 are 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 Pb contamination and higher prevalence of elevated children’s blood Pb than same-aged brick public properties in the outlying urban areas. The median Pb dust in the inner-city soil was 438 mg/kg or 3.7 times larger than median soil Pb of 117 mg/kg (p-value <0.0001). 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 <0.0001). Lead dust from gasoline additives explains the discrepancy of soil Pb and children’s blood Pb in the traffic congested inner-city core compared with the lower traffic outer areas of New Orleans. Similar patterns of environmental Pb dust contamination and childhood Pb exposure are expected in all US cities. To meet the goal of primary childhood Pb prevention, the findings underscore the need for revised soil policies that act to eliminate the impact on children of Pb dust that has accumulated in urban soils.