"Acetone" smell on bread
I wouldn't see it as safe to eat. I cannot imagine that the acetone was present when you bought the bread (QA should have caught this if it happens every now and then), so it must be the byproduct of some microorganism chomping down on the bread. Especially if you say that it develops over time. 

On the chance that it is mold (this is more common in bread than bacteria), try keeping it with less humidity. If it is in a plastic bag or in a bread box, stop doing that. Use a paper bag or leave it naked, and not in the direct way of fumes (e.g. a shelf above the stove). 

Seeing that this bread has sprouted grains in it, it could even be moist enough to have bacteria colonizing it. Still, the remedy is the same. Store it in a dry location.