Compounding hazards posed by wildfires, flooding, and resource extraction: Assessing multimedia metal(loid) exposures and risk in rural, southwestern U.S. Populations

Understanding the extent of contamination due to climatic events in rural areas is necessary to protect environmental health, especially when these spaces disproportionately bear the burden of resource extraction. Using a Monte Carlo-based probabilistic assessment, this study investigates how wildfire and subsequent flooding influences As, Cd, Cu, Cr, Pb, Mn, Ni, and Zn exposure from non-residential sediment and residential soil and indoor/outdoor dust. Carcinogenic/cumulative target cancer risk (TCR) and noncarcinogenic/cumulative hazard index (HI) were evaluated across multiple exposure pathways and scenarios (residential, nonresidential) for children and adults in rural, Arizona communities. In residential settings, flooding significantly increased (p ≤ 0.05) Pb and Cu surface soil concentrations. In both populations, HI_flooded > 1, while TCR_flooded falls within the tolerable U.S.EPA risk threshold. The mean HI_t-Child > 1 was driven by As, Cu, and Mn in outdoor dust followed by Pb and Zn in soil. Arsenic incidental ingestion and to a lesser degree Pb from residential outdoor dust was the prominent exposure pathway, leading to 1.6 cancer cases for every 10,000 children, whereas an adult's exposure/associated risk was dominated by soil. Outdoor dust led to an unacceptable carcinogenic risk for children and cleanup efforts are imperative. Children growing up in rural, southwestern resource extraction communities experiencing climate extremes are bearing the burden, facing increased health risks. When navigating climatic challenges in rural, resource extraction regions, community-centered environmental research translation and nature-based solutions are critical to mitigating environmental exposures and associated health risks.