When it is the employer will realize what is going on. If that's not a possibility then I agree with talking to the employer about the policy for shredding documents.
Talk to the employer about the policy of shredding documents. He or she is going to ask you why you need to know....you then say an employee has been shredding documents and you were concerned. The employer will ask your slack worker what they are doing and the added attention and questions might bring out their behavior.
Its hard to not look like a whinger right? Its hard when you are working and they are slacking off. But there are ways of bringing these things up in a way that brings attention to the problem without being nasty and difficult.
And gees if all else fails, take photos on your camera - send them to the worker - see what happens :) ( well, might not be great idea but might make you feel better :).
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.