Environmental availability and human health risks of Zn and Mn in battery waste assessed by sequential extraction

Abstract In Brazil, a considerable portion of electronic waste, such as batteries and accumulators, is still discarded with household trash and sent to landfills without sanitary or environmental control. Improper disposal can lead to the accumulation of potentially toxic metals, posing risks to ecosystems and human health. This study evaluated the performance of a modified Bureau Community of Reference sequential extraction protocol applied to battery waste, focusing on the environmental availability of Zn and Mn. The protocol showed good repeatability, with relative standard deviations ranging from 0.627 to 16.4%. Spike and recovery assays yielded satisfactory values, with recoveries between 94.3% and 134%, while extraction yields ranged from 94.3% to 130% across all samples. These results confirm the suitability of the modified protocol for evaluating Zn and Mn in this matrix. A significant mobilization of both metals occurred in the first three extraction stages, highlighting the potential for soil and water contamination under improper disposal. The potentially mobile fraction of Zn was higher than 80%, indicating a greater environmental threat compared to Mn. To complement the chemical assessment, a hypothetical risk scenario was modeled for disposal in urban soils. Using the risk assessment tool, exposure of adults and children was simulated through soil ingestion and consumption of vegetables cultivated in contaminated areas. The modeling revealed potential health risks for both groups through at least one exposure pathway. These findings reinforce the urgency of safer disposal practices and recycling strategies for battery waste, reducing risks to both the environment and public health.