Mechanisms and health implications of toxicity increment from arsenate-containing iron mineral through an in vitro inhalation bioaccessibility method

Inhalation is an important exposure pathway for metalloids, particularly arsenic (As), in soil and dust. Although previous studies have identified potential health risks associated with bioaccessible As, the mechanisms governing its mobilization and their health implications remain poorly understood. This study investigated As release and solid-liquid interfacial reactions involving As(V)-bearing iron minerals in artificial lysosomal fluid (ALF). The maximum As release from goethite in ALF was 0.14 mg/L. Mechanistic analyses indicated that acid dissolution and reductive dissolution of iron minerals primarily governed As release. Incubation of As-bearing goethite in acidic ALF released dissolved As and Fe, accompanied by detection of As(III) and Fe(II). Combined aqueous speciation and solid-phase characterization results were consistent with alteration of As-bearing goethite under acidic, ligand-containing conditions; however, the specific pathways responsible for As and Fe transformations were not directly determined. These findings advance mechanistic understanding of As release and speciation transformations from synthetic As-bearing goethite under acidic, lysosome-like conditions. Although these in vitro results do not directly estimate internal dose, disease risk, or regulatory thresholds, they highlight the importance of considering As speciation, iron-mineral reactivity, and inhalation bioaccessibility in future assessments of As-containing dust and particulate materials.