To the op: I dont know about the product you are talking about, but limonene is reasonably safe.. Its ingested in small amounts as food-supplement by some people. But this doesnt mean you should be over-breathing, taking baths in it or drinking a glassfull, of course
I guess when people say its safe, they mean that, for example, if you have traces of limonene in your dmt fumarate, for example, it wouldnt be a problem to ingest a tiny bit of it, or to breathe a bit while extracting or whatever, while the same couldnt really be said about petrochemicals such as xylene and others.
And yeah, elru, it can irritate one's skin... Though I've noticed this also has to do with one's individual sensitivity. Personally limonene doesnt really iritate much my skin, but I know for some people it does.