How to tell what user has synced

I have set up merge replication web sync to sync a publication from a SQL Server 2012 database. I am trying to make some parameterised filters using SUSER_SNAME() or HOST_NAME(). When I do a sync is it possible to find somewhere what the values of SUSER_SNAME() and HOST_NAME() actually were for that sync? E.g. in the system tables. I will need to experiment with security to work out what settings will affect these values, but I will need to find out what these values actually are to verify my settings.