In the state of n.y. can a juvenile record be used against an adult who is incarcerated for unrelated issues to reject his application for work release? (he is in on a parole violation with no new charges stemming from unrelated incidents?

Yes. A juvenile record can be taken into account by a judge in a an adult court after the person reaches the age of majority when a judge is sentencing, setting bail, reviewing parole recommendations and so forth.

A juvenile record (unless expunged) is visible to the Court and police officers and can be used in future legal proceedings.