A few months ago, we were told to clear several newly planted containers (the long rectangular plastic ones) off our balcony as part of preparing for the entire building to get repainted. We put them in the backyard, which is shared by the downstairs units, and when we retrieved them three weeks later discovered that the neighbors' indoor/outdoor cat had left solid presents in one of the pots. It might have peed in there too, I don't know - we're in San Francisco and soil tends to dry out fast.

Only one thing (I think it's a carrot) ever sprouted in that pot (we aren't the most attentive gardeners anyway), but is the soil still safe for growing edible things? Leaf vegetables only? Fruiting vegetables only?