Community-Engaged Assessment of Soil Lead Contamination in Atlanta Urban Growing Spaces

Abstract

Urban agriculture is emerging as a method to improve food security and public health in cities across the United States. However, an increased risk of exposure to heavy metals and metalloids (HMM) exists through interaction with contaminated soil. Community-engaged research (CEnR) is one method that can promote the inclusion of all partners when studying exposures such as HMM in soil. Researchers and community gardeners co-designed this study to measure the concentrations of lead (Pb), using X-Ray Fluorescence (XRF) verified with Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) in soils from 19 urban agricultural and residential sites in the Westside of Atlanta and three rural sites in Georgia. Seventeen other HMM were measured but not included in this study, because they did not pose risks to the community comparable to elevated Pb levels. Pb concentrations were compared to the Environmental Protection Agency (EPA)'s regional screening levels (RSLs) for residential soil and the University of Georgia (UGA) extension service's low-risk levels (LRLs) for agriculture. Soils from the majority of sites had levels below EPA RSLs for Pb, yet above the UGA LRL. However, soil Pb concentrations were three times higher than the EPA RSL on some sites that contained metal refining waste or slag. Our findings led to direct action by local and federal government agencies to initiate the cleanup of slag residue. Studies involving exposures to communities should engage those affected throughout the process for maximum impact.

Keywords: community‐engaged research; heavy metals; regional screening levels; soil; urban agriculture.

Figure 1

Mean 95% upper confidence levels (UCL) for lead (Pb) in rural background (Bck), residential (Res), and urban agricultural (Agr) sites is displayed in the graph on the left. The subset of samples analyzed by both X‐ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP‐MS) is displayed in the graph on the right. EPA regional screening levels (RSL) are denoted by red lines and UGA low risk levels (LRLs) are denoted in green. Error bars are 95% confidence intervals of the mean in the XRF graphs and one standard deviation of distributions in XRF/ICP‐Ms graphs due to limited ICP‐MS sample size.

Figure 2

Correlation between X‐ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP‐MS) measurements of Pb (R ² = 0.72). Orange line represents an ideal 1:1 relationship between XRF and ICP‐MS measurements and blue dots represent observed concentrations from both instruments. All concentrations are in ppm.

Figure 3

X‐ray fluorescence (XRF) mean upper confidence limits (UCLs) of lead (Pb) between rural background, urban samples, slag site soils, and slag pieces. All results are in parts per million (ppm). 95% confidence intervals are presented as error bars. EPA regional screening levels (RSLs) are denoted by a red line and UGA low risk levels (LRLs) are denoted in green.