It's not the pee, it is the feces, and only dangerous if the kittens
a) have toxoplasmosis (most cats are not walking around with a live case of this; you could be in an area where it is not even common)
b) you have not ever been exposed to toxoplasmosis before (your doctor can test for this)
c) if the feces sit in a catbox longer than three days (that time length being necessary for the oocytes to develop in the feces to a point where they could be transmitted to you), and
d) you ingest the fecal matter
You're at more risk of developing toxoplasmosis if you garden with bare hands than just from being near a cat or a catbox.
You can be in the area but make sure you wash your hands a lot and extremely well. And if you have to deal with it in the future wear gloves and maybe a mask. But one time you should be ok. If you're super worried call your doc