Assessing gallium arsenide health risk: critical insights for protecting workers and the environment

• Pioneering GaAs risk assessment integrating BMD, RDDR, and particle deposition analysis. • Derived risk metrics (RfC, REL) are substantially more protective than current OELs. • HQs exceed 1.0 for all worker categories, including administrative staff. • Urgent need to update OELs and implement particle-size-aware monitoring strategies. Gallium arsenide (GaAs), a critical material in the rapidly expanding semiconductor industry, potentially poses a growing occupational and environmental health concern. Current occupational exposure limits (OELs) for GaAs are largely based on inorganic arsenic regulations, which fail to account for the unique toxicological profile and potential synergistic effects of its components. This study provides a rigorous human health risk assessment to inform decision-makers on the re-evaluation of existing regulatory standards. Benchmark dose modeling two-year inhalation study data from the United States National Toxicology Program identified chronic-active lung inflammation in male rats as the critical endpoint. We calculated a benchmark concentration lower 95% limit (BMCL 5 ) of 8.0 × 10 −4 mg GaAs/m 3 . Applying the Regional Deposited Dose Ratio model and an additional uncertainty factor of 30 for species extrapolation yielded a reference concentration of 1.71 × 10 −5 mg GaAs/m 3 and a recommended exposure limit of 1.26 × 10 −4 mg GaAs/m 3 . A risk assessment using personal sampling data for exposed engineers, operators, and administrative staff found the minimum mean hazard quotient to be 61, dramatically exceeding the acceptable level of 1. These results demonstrate a substantial health risk under current occupational conditions, emphasizing the inadequacy of the existing OEL of 0.01 mg GaAs/m 3 . This study highlights an urgent need to revise occupational and environmental GaAs exposure guidelines to protect both workers and residents in this critical and rapidly growing industry