REDUCING THE LEAD-LOAD FOR URBAN YOUTH: THE ROLE OF ATMOSPHERIC SOIL RE-SUSPENSION AS A SIGNIFICANT PUBLIC HEALTH THREAT IN THE UNITED STATES

Children's lead poisoning in urban areas in the United States follows a seasonal pattern with a peak in the summer months. We recently found that that weather and soil moisture variables robustly predicted seasonal changes in children's blood lead levels in a number of US cities. We concluded that the weather and soil moisture variables were a proxy of seasonal soil re-suspension and exposure of children to lead contaminated urban soils, with the potential to use site-specific weather and soil moisture determinations to better assess clinical blood Pb data.

In order to test the hypothesis that atmospheric soil concentrations display a seasonal pattern, time series of atmospheric soil concentrations were obtained at eight IMPROVE locations across the United States. Results indicate that continental atmospheric soil concentrations exhibit strong seasonality and increase up to an order of magnitude between winter (minimum) and summer (maximum). In order to test the hypothesis that atmospheric soil seasonality is related to weather and soil moisture variables, atmospheric soil concentrations at the Bondville, Illinois IMPROVE site were regressed against the independent variables minimum relative humidity, field measured soil moisture, precipitation, temperature, wind speed, atmospheric pressure, while adjusting for the month of the year. The model time period was 37 months. Results indicate that eighty-three percent of the temporal variation of atmospheric soil concentrations (R2=0.83, p = <0.001, DW = 2.06), could be explained by these variables. Our empirical model indicates that when temperatures are high, relative humidity is low, and evapotranspiration maximized, soil moisture decreases, and soil dust is re-suspended into the atmosphere. Correlation of local atmospheric soil concentrations with local soil moisture and atmospheric data suggests that a significant proportion of the atmospheric soil is derived from local sources. The findings that weather and soil moisture variables predict atmospheric soil seasonality (this study) and children's blood lead levels (our previous work) support the hypothesis that seasonal re-suspension of local lead contaminated soils in urban environments is driving seasonal lead poisoning.