Evaluation of the Acute Effects of Inhaled Toxicants on an Alveolar Epithelial Model

Brazil′s Law 15.022 establishes the National Inventory of Chemical Substances, regulating risk assessment and control while promoting nonanimal testing and allowing animal testing only as a last resort. Traditionally, the assessment of acute inhalation toxicity has relied heavily on animal testing, which is costly, time‐consuming, and raises ethical concerns. Regulatory agencies have increased the demand for information on inhalation toxicity, particularly for companies producing and distributing chemicals on a large scale. This study was aimed at evaluating the cytotoxic potential of inhaled toxicants and classifying them according to the Globally Harmonized System (GHS). In addition, we compared different forms of exposure, both liquid and aerosol, to assess potential differences in the observed effects. In this study, an in-house model cultured at the air–liquid interface (ALI) using human alveolar lung cells A549 was used and exposed to different pulmonary toxicants categorized in the GHS (Categories 1–5) to study the cytotoxicity profile. The results showed a significant correlation between the cytotoxicity of the compounds and their GHS classifications. Furthermore, the study sought to establish a correlation between in vitro IC50 values and in vivo LC50 data, indicating potential for predicting acute inhalation toxicity. Besides, exposure to aerosols showed a stronger cytotoxic effect than exposure to liquids, highlighting the importance of accurately reproducing real‐world exposure conditions in toxicological studies. In conclusion, the in‐house alveolar model represents a promising refinement tool for evaluating acute inhalation toxicity. It provides a consistent assay for compound screening, supports regulatory requirements for advanced pulmonary toxicity assessments, and contributes to the global effort to reduce reliance on animal testing in toxicological research.