I think putting some oil on the whitened balls and then wiping them off with an old rag you don't mind throwing away is good enough to get the balls back in shooting condition.
I'd wash my hands after throwing the rag away but that's about as far as I would go.
Looking at your age, you like me and a bunch of others here are all part of the Invincible Kids.
You know. The ones that put lead in their mouths and bit it to see if it would have tooth marks. We coated penny's with mercury to make them shiny and put Calcium carbide and a little water in a paint can and then put the lid with a hole in it back on top. Holding a match near the little hole would cause an explosion that would blow the lid a good 50 feet high.
I also recall poking a hole in the lid of a Skippy peanut butter jar and putting some lye water and aluminum foil in it before screwing the lid back on. Usually, if one waited a while they could light the pure hydrogen gas that was bubbling off.
Then, one day I got in a hurry as I was showing this neat trick to my buddy Bob.
There was still some oxygen in the jar and instead of lighting a nice transparent flame, the jar exploded blowing glass and lye water all over the place.
I didn't get a scratch but the lye water ate the paint off of the desk in my bedroom. :rotf:
We also could buy real black powder in a paper sack from the war surplus stores and shoot off our calcium carbide noise maker cannons.
We all made rubber band pistols and played war shooting each other with pieces of bicycle inner tubes and often had dirt clod fights throwing 2 inch clods at each other. (Damn! Those hurt when they hit you in the head!)
Anyway, as I say, we are the Invincible Kids.
Just clean the balls up and shoot them.