pg_attribute growing extremely

Hi,

on a server running 8.4 I observe that, since a while, the pg_attribute table is growing
enormously. 
Soon after reloading I have one file
ls -s 1249
1048580 1249
a day later this is 
1048580 1249
1048580 1249.1
1048580 1249.10
1048580 1249.11
1048580 1249.12
1048580 1249.13
1048580 1249.14
1048580 1249.15
 682212 1249.16
1048580 1249.2
1048580 1249.3
1048580 1249.4
1048580 1249.5
1048580 1249.6
1048580 1249.7
1048580 1249.8
1048580 1249.9
   4316 1249_fsm
     24 1249_vm
and 5 days later the system had arrived at 102 files

The server is running since quite some time, without any major change.
The workload is mostly reading, a little text updates and a little more binary updates.
Every two weeks or so the database is recreated and reloaded
The total size of data is growing slowly (say a rate of 10% per year)

Regards
Wolfgang Hamann