"Not Usable By X" A Disadvantage?

[Gidoza]

I couldn't find this one in the FAQ, so I thought I'd ask.

If an item says, for example, "Not usable by Dwarf," but I am a Half-Breed Dwarf with no second race, may I use this item? Basically, I am asking whether the "not usable by dwarf" phrase counts as a disadvantage to a race in the same way that a monster's "+5 against Dwarves" would count as a disadvantage to a race.