Can white noise at the work place be harmful?

Not to my knowledge: There are some animal studies with exposures to very loud white noise that would stress / deafen anyone. The internet's premiere compiler of junk science is campaigning against these generators. If they do not make you uncomfortable, I think the concerns are silly.

Possibly: Any noise, if loud enough, can cause hearing loss. More information would be necessary to conclusively answer your question. The Occupational Safety and Health Administration may be a resource for you.