I just tried to verify this online, but was unsuccessful......I'm pretty sure I saw some information at one time that said the Watco Danish Oil finish loses it's toxicity once fully cured and dry. (Can someone verify this?)
Anyway, if it's feasible to re-sand the surface of your bowl, you might want to do that, prior to applying a salad bowl finish.
The Danish Oil is a penetrating finish, while the salad bowl finish is a surface preparation and sealant.
I have never attempted doing this, but have given it consideration before......so, I'm speaking strictly on a theoretical basis. You should trust nothing of what I'm suggesting as coming from an experienced point of view......just use your good judgement, and any helpful advice that may follow.
It's my best guess that lightly sanding the surface, and refininsing with a salad bowl finish ought to work for your purposes.
good luck
otis of cologne