High Resolution Models of Groundwater Metal Exposures

Project 1 Summary The long-running Strong Heart Study documented high urinary arsenic (As) and uranium (U) levels in Native American tribal study sites relative to the general US population. Elevated exposures to metals and metalloids (hereafter metals) potentially contribute to the epidemic of cardiometabolic disease affecting tribal and other rural communities in the US. In rural communities of the Northern Plains, drinking water is commonly derived from unregulated and largely unmonitored private wells or public water systems that draw from the same aquifers. Much of the As and U exposure likely results from elevated levels of metals in groundwater sources. However, groundwater data are relatively scarce for rural communities, especially from tribal regions, making it difficult to identify groundwater hazards, and to mitigate their exposures. Project 1 of the Columbia University Northern Plains Superfund Research Program (CUNP-SRP) uses a two-pronged approach to address a critical gap in our understanding of the distribution of groundwater contamination and exposure across rural areas including Native American tribal areas. First, we will integrate existing and new measurements of groundwater composition data with prior large mineralogical and chemical speciation data sets. Second, we will use a combination of groundwater composition in wells and remotely sensed hydrological and other variables to develop machine learning-based predictive models of groundwater contaminant levels at the household scale—the foundational data needed for exposure assessment. We have 3 specific aims. Aim 1 will analyze drinking water sources from the CUNP-SRP field areas to identify and better understand the mobilization mechanisms of As and U into drinking water. Aim 2 will develop process-based models that predict As and U drinking water concentrations at the household scale across the Northern Plains. Aim 3 will develop and validate As and U drinking water exposure profiles for the Strong Heart Arsenic and Uranium Lifelong (SHAUL) cohort (for Project 3) by comparing spatial and temporal variability and trends in water metal concentrations, water use, and detailed residential histories with urinary-based exposures for tribal participants from all SHAUL locations. We will also evaluate the impact of policy interventions on drinking water As and U exposures, including those from changes in water sources and use, implementation of As MCL on contaminant concentrations in CWSs, and implementation of point-of-use filtration. Combined, our data and models will provide improved understanding of environmental exposures that is needed for the CUNP-SRP to contextualize the health effects of hazardous metal mixtures (Projects 3 and 4), to identify mitigation pathways to clean water (Project 5), and to allow the Community Engagement and Administrative Cores to make the environmental data and their interpretations accessible to these tribal communities. Ultimately, the results of these efforts in data collection, modeling, and additional data analysis will help identify at-risk populations and develop effective interventions to reduce potentially dangerous exposures to contaminated drinking water in the Northern Plains and beyond.