The phrase "are caused" can be substituted with a variety of other words or phrases to add variety and nuance to your writing. For instance, instead of using "are caused," consider using alternatives such as "trigger," "initiate," "instigate," "bring about," "prompt," "provoke," "engender," "induce," or "generate." Each of these synonyms brings a slightly different connotation and will help to enhance the tone and style of your writing. Being mindful of the different synonyms available will help you to capture the exact meaning and tone you are trying to convey, leading to clearer and more engaging writing.