SOURCES AND PATHWAYS OF LEAD CONTAMINATION IN URBAN COMMUNITY GARDENS IN TOLEDO, OHIO

The benefits of community gardens including sources of healthy produce in urban inner city settings is well established. However, community gardens also provide ready access to potentially contaminated soils. As with many older urban areas, Toledo, OH has a legacy of lead contamination and previous research has shown highly elevated Pb levels in inner city residential soils that are reflected in elevated blood lead levels in children under age 6 (Stewart et al., 2014). The primary source of Pb in young children’s blood is from hand-to-mouth ingestion of contaminated soils. As such, this study focused on identifying community gardens with elevated Pb levels (above EPA guidelines) and to evaluate the migration and transfer of Pb through the different construction and maintenance practices adopted by different gardens (eg, raised vs in-ground beds, use of different types of bed liners, etc) and the age of the beds. Also, samples were taken at the surface (top 5 cm) and at typical root depths (20-30 cm) to evaluate the amount of Pb available through direct ingestion versus plant uptake, and the rate Pb was migrating through the beds. Sampling was also guided by the locations of buildings (driplines) and roadways using historical maps (back to 1882) of residential and industrial building locations from the Sanborn Fire Insurance maps. Over 100 samples were collected from 27 gardens in the Toledo area that had a range of gardening practices and ages. Samples were digested using USEPA method 3051A and analyzed using method 6010C. The results show that 1) height of raised beds (depth of soil) above surrounding ground level has a significant impact on reducing surface sample Pb, and is especially notable where gardens are positioned over soils with highly elevated Pb levels, 2) garden samples taken at root depth have Pb values up to 16 times greater than surface values, 3) age of housing (historic use of Pb-based paints) and positioning of garden along present and former driplines is the main factor leading to elevated Pb levels, 4) gardens without liners show higher lead values than gardens with liners, 5) in-ground gardens show higher Pb than raised beds.