MAPPING THE URBAN LEAD EXPOSOME: A DETAILED ANALYSIS OF SOIL AND DUST METAL CONCENTRATIONS AT THE HOUSEHOLD SCALE USING CITIZEN SCIENCE (Invited Presentation)

Lead is a pernicious and persistent poisoning, sickening over a 1/3 of children around the globe. It's negative impacts on intellectual development are permanent, and hazards will only go away if we identify and eradicate exposure routes from air, soil, and water. An ambitious global citizen science effort, www.MapMyEnvironment.com aims to collect and analyze tens of thousands of soil and dust samples at the property scale, thus providing the science to understand distribution and the knowledge to eradicate hotspots at the property scale.

A number of important outcomes have arisen from this new program. First, at some sites we were able to parse soil metal concentrations as a function of property location (i.e., dripline, yard, and street) and location within the city. This effort indicated that dripline soils had substantially higher values of lead and zinc than other soil locations on a given property, and this pattern was heightened in properties nearer the urban core. The main reason for this trend is likely a combination of degrading lead-based paints on the exteriors of some homes and the characteristics of aerodynamic obstacles, such as homes, to collect and concentrate dust near the perimeter. Soil lead values typically exceeded the levels deemed safe for children’s play areas in the United States (<400 ppm), and almost always exceeded safe gardening guidelines (<200 ppm). Second, although still in its initial stages, we found high values of lead in interior dust, particularly in urban cores, and the relationship between soil and dust lead concentrations was fairly robust, supporting the importance of intrusion of exterior dust into homes as an exposure pathways for lead. More work us underway on characterizing dust exposure and geochemistry, and on understanding differences between various metals in terms of soil:dust ratios. As a whole, this study identified locations within properties and cities that exhibited the highest exposure risk to children, and also exhibited the power of citizen science to produce data at a spatial scale (i.e., within a property boundary), which is usually impossible to feasibly collect in a typical research study.