Community-engaged, course-based analysis of soil lead contamination near a historical metallurgy facility in Los Angeles, California

Abstract Legacy Industrial lead (Pb) contamination poses a public health problem in many areas worldwide. In Southeast Los Angeles, California, a history of incompatible land use and concentrated industrial activity has raised concern about Pb contamination in the area’s neighborhoods, particularly in Huntington Park. One former industrial facility in Huntington Park has attracted attention from both a local community environmental justice organization and the U.S. Environmental Protection Agency (USEPA). Although a 2023 report by the USEPA concluded that the Pb contamination from this site was insignificant, the 2024 reduction of the federal soil screening level for residential soil-Pb–from 400 mg/kg to 200 mg/kg–prompted a reassessment. Collaborating with environmental justice organization Communities for a Better Environment, researchers at the University of California, Los Angeles analyzed 91 residential soil samples in Huntington Park and compared them with 118 samples from the broader of Los Angeles area while incorporating course-based experiential learning opportunities for undergraduate students. In Huntington Park, 85.7% and 57.2% of soils exceeded the state (80 mg/kg) and new federal (200 mg/kg) screening levels, respectively–compared to 55.9% and 19.6% citywide. A statistically significant difference in soil-Pb was found between the residential soils in Huntington Park and the rest of Greater Los Angeles (Mann-Whitney U, p < 0.01). Soil Pb concentrations also correlated significantly with proximity to the industrial site. Notably, 49.5% of Huntington Park soils fell between the updated and the former federal screening level, highlighting the need for reevaluation of the area's contamination. These results also emphasize the need for remedial action to be taken in areas like Huntington Park, which serves as a clear example of disproportionate contaminant exposure faced by disadvantaged/minority communities.