Asbestos - please EVERYONE - look it up!
Is harmful only if inhaled.
Only tiny fibers can become airborne, and you have to breathe the stuff for a looooong time to get enough to clog your lungs or cause cancer.
Fill the damned sandbox and let the kid play!
Prop 65 was sabotaged by industry so as to include simply everything - to the point that it is virtually meaningless. They actually tried to get it to cover chemical found in drinking water, but that was shot down.