Definitely write to the IT admin and get them to ban Reddit also. They probably haven't banned it yet because they like to go on it, so if that is the case write to their bosses and say

"I have witnessed a lot of disturbing content on screens in the IT department. I don't want to name names, but suffice it to say, a lot of extremist and violent imagery is being viewed on Reddit.com. As someone who values a safe and productive work environment, I suggest we add reddit to the ban list."