Is there a risk my Statement of Purpose will be plagiarized if I post it online? I am currently looking to send my Statement of Purpose to an English TA for editing. The problem is that I am afraid my Statement of Purpose might get plagiarized. However, since my statement is highly personalized, is my worry unnecessary?
This is very unlikely if you do your statement of purpose well: the document should be too specific to your situation and interests to apply to your English TA. 

To reduce the chances of it being plagiarised, try considering some standard tips for a good statement of purpose [emphasis mine]:


  
  Tell them what you’re interested in, and perhaps, what sparked your desire for graduate study. This should be short and to the point; don’t spend a great deal of time on autobiography.
  [Summarize...] [r]esearch you conducted. Indicate with whom, the title of the project, what your responsibilities were, and the outcome. Write technically, or in the style of your discipline. Professors are the people who read these statements.
  


And so on. The common theme among these and the remaining tips is that the statement of purpose should really highlight your unique qualifications and interests.