After digging a dry well and taking soil samples for testing, I have a bunch of excess soil from my garden, just sitting in a bucket in my garage. It occurred to me to use it to make some hikaru dorodango. However, because I took soil samples for testing, I know that there's a bunch of lead and other contaminants in there. Obviously it's no good for growing food; is it safe to use for this purpose instead? (In other words, can I safely handle it?)
I would say yes---carefully.
DISCLAIMER: I AM NOT AN EXPERT IN MATERIALS SAFETY. I do some work that involves lead bricks, but you should look for other confirmation besides mine.
The main precautions I would take would be taking care to avoid generating a lot of dust (you don't want to breathe lead dust) and wash your hands after working with the soil. As long as you do those things I would say you should be pretty safe.
AGAIN, I AM NOT AN EXPERT.
But those are the precautions that I would take before dealing with the soil.