List and describe at least three discipline areas in which a modern safety and health manager might require to have at least a basic leel of competency

List and describe at least three discipline areas in which a modern safety and health manager might require to have at least a basic leel of competency.  What are some common, predictable problems that a safety and health manager might face during the course of their practice?
 
Must be at least 200 words in length.  all sources used, must be referenced parapharased and quoted material