Void stuff

Void stuff, as it was described by the Tenth Doctor, is a type of background radiation that clings to those who have travelled through the Void. The Doctor was able to show its presence on himself and all those who had travelled to or from Pete's World with his 3-D glasses. A full opening of any breach that opens into the Void will violently pull the matter back in along with anything that it is clinging to.

During the Battle of Canary Wharf, the Daleks from the Genesis Ark and the Cybermen were more susceptible to being pulled in because they had been super-saturated with Void stuff. (DW: Doomsday)