Huge Size of system tables

Hi,

I have recently joined a new company with X6-2 in place  running EBS R12.1.3 ( 4 application nodes ) and 3 node RAC (12.1.0.2)

the most unusual thing i observed was size of system table space ( 450GB)

upon quick analysis , i found below segments taking most of the space .

IDL_UB2$                         150G

C_TOID_VERSION#          25G

obj$                                   100G

Has anyone experienced similar growth? and how can i purge ( i do see only 470000 rows on IDL_UB2$)

one of the downside of this is performance ( application patches take long time) , apart from the wastage of expensive storage.