Answer:
Cesium compounds normally found are not considered particularly toxic, though, like anything else, an excessive amount of cesium is not good for you. It is said to make people irritable and cause spasm because it replaces potassium in the body.
Metallic cesium reacts violently with water, and is not something you want to touch.
Cesium isotopes leaked from nuclear power plants can be a serious problem because of their radioactivity.