Changes in community members’ toenail metal concentrations after cessation of nearby open-burn thermal treatment of munitions waste

Background Colfax, LA, is a rural, predominantly minority community, where an open-burn/open-detonation (OB/OD) hazardous waste thermal treatment (TT) facility operated until December 2023. Objective This study aimed to identify the presence of metals in the toenails of Colfax residents before and after cessation of OB/OD. Methods Toenail samples were collected from community members in 2023–2024 (during facility operation) and 2025 (post-cessation) at locations near ( < 7.5 km) and far ( > 7.5 km) from the facility. Results Elevated levels of heavy metals, including lead, were observed in 2023–2024, with generally lower concentrations in 2025. Statistically significant decreases were observed for molybdenum, nickel, and lead after OB/OD ceased. In the 2023–2024 collection, samples obtained closer to the facility were more likely to have elevated levels of aluminium, iron, nickel, and lead. SIGNIFICANCE Exposure to OB/OD likely contributed to increased metal body burden among Colfax residents. Results suggest cessation of operations reduced community exposures to heavy metals. Impact Open-burn/open-detonation (OB/OD) hazardous waste thermal treatment poses risk of exposure to toxic contaminants, including heavy metals, environmentally persistent free radicals, dioxins, and furans. We measured changes in toenail concentrations of heavy metals while an OB/OD facility was in operation and again 15 months after cessation. Our data suggests that cessation of OB/OD results in decreased exposure and reduced body burden for some toxic metals, including lead, aluminium, iron, and nickel.