Complex sentence: Portland cement is caustic, so it can cause chemical burns, the powder can cause irritation or with severe exposure lung cancer, and can contain some hazardous components such as crystalline silica and hexavalent chromium.
Split into simpler sentences: Portland cement is caustic, so it can cause chemical burns. The powder can cause irritation or, with severe exposure, lung cancer and can contain some hazardous components such as crystalline silica and hexavalent chromium.