I don't think that it pulls out toxins but I do believe that it gets the lymphatic system moving which has accumulated toxins and clears it out. I've used the castor oil packs on my stomach and legs with good results in both areas, but I bet that putting it in the socks will be beneficial as well. It sure can't hurt. The castor oil is a demon to get out of cloth or clothing once its been exposed so use socks that you don't wish to see any more and put plastic over the socks or you'll really have a mess.
When a cold or sore throat comes on, often times I'll chop up garlic and put that in my socks and sleep with that on, and it helps keep me from being too congested. I can actually taste the garlic within 60 seconds of putting the socks on my feet.