Cadmium exposure is associated with damage to which alveolar cells?

• A. Type 1 alveolar epithelial cells
• B. Type 2 alveolar cells
• C. Macrophages
• D. Endothelial cells

Answer: (A)

Cadmium inhalation targets the delicate lining of the air sacs, with the thin, expansive surface provided by Type I alveolar epithelial cells taking the primary hit. These cells form the major gas-exchange barrier, so when they are damaged, the alveolar–capillary barrier becomes leaky, leading to edema and impaired diffusion of oxygen and carbon dioxide. Type I cells are very thin and cover most of the alveolar surface, making them highly susceptible to toxic injury. Type II cells, which produce surfactant and can proliferate to repair the epithelium, are more resilient in this context, and alveolar macrophages or endothelial cells play roles in inflammation or capillary lining but are not the main alveolar surface cells damaged by cadmium.