Wednesday, November 15, 2006 - 11:05 AM

Soils and Society: The Human Health Legacy of Urban Lead Contamination.

Gabriel Filippelli, IUPUI, Dept of Earth Sciences, 723 West Michigan St, Indianapolis, IN 46202-5132 and Mark Laidlaw, School of Population Health, Univ of Western Australia, Perth, Australia.

The intersection between geological sciences and human health is gaining significant interest as we understand more completely coupled biogeochemical systems. An example of such a problem largely considered solved is that of lead (Pb) poisoning. With aggressive removal of the major sources of Pb to the environment, including Pb-based paint, leaded gasoline, lead pipes and solder, the number of children in the United States affected by Pb poisoning has been reduced by 80%, down to a current level of 2%. In contrast to this national average, however, more than 16% of urban children exhibit blood Pb levels above what has been deemed “safe” (10 micrograms per deciliter); most of these are children of low socio-economic minority groups. We have analyzed the spatial relationship between Pb toxicity and metropolitan roadways several US cities and conclude that Pb contamination in soils adjacent to roadways, the cumulative residue from the combustion of leaded gasoline, is being remobilized. We have also found that seasonal trends in children’s blood lead levels seems to be controlled by exposure to lead-enriched dust originating from contaminated soils and suspended in the air when several weather related environmental conditions are present: temperature is high, soil moisture is low, and fine particulate is elevated. Under these combined weather conditions, lead-enriched dust disperses in the urban environment and is manifest by elevated lead dust loading. In this case, exposure is via increased dust loads in homes and on contact surfaces, with ingestion being the uptake mechanism. Although further work using detailed tracking of lead, possibly involving lead isotopic studies, may help to elucidate the connection between seasonality and blood lead values, these results indicate that the ability of geochemical and meteorological factors to predict blood lead supports the supposition that external loading and exposure drives much of the blood lead concentrations.