User blog comment:Night at the Kashmir/Partygoer Models from Bioshock 2's intro/@comment-10023421-20140315104649/@comment-75.36.140.119-20140316053808

Nothing says they were 'Splicers' (ADAM users and/or abusers)

Not everyone in Rapture used ADAM particularly at that time.

Use went up drasticly when the Civil War started, but even then not everyone used ADAM  and one reason could be lack of supply and cost and monopolization between Atlas/Fontaine and Ryan using it to boost their forces.