Torus dregs can be some hot stuff. Consider a plant with some fuel defects and the Iodine and radionasties that go with it.
Pop an SRV, steam flow transports the radionasties into the Torus along with a load of tailpipe rust, necessitating cleaning.
Noble Gases stay in the airspace and decay into particulates. Nice rounded shape allows for settling, suction strainers allow a place for chunks to call home. Drain that donut for cleaning, the shielding goes down the drain, and voila - nastified Torus.
If it is or ever has been connected to an RCS - it can be nasty.
Play nice, chirrun.