Kids Throwing Curve Balls

First of all, I'm neither a proponent or opponent of kids younger than, let's say...14, throwing curve balls. I like to make decisions based on the best data available at the time, but I have yet to see anything other than opinion expressed on this subject. All that I know from being around kids for 30+ years is that kids from the age of 8 will fool around with this pitch. Many will throw it in a game situation as early as 9-10 years old.

I myself have never seen an arm injury attributed solely to throwing a curveball, although there may be many such cases.

Can anyone site a study done on this subject? I'm not too interested in hearing about isolated cases unless they were proven to be caused by throwing a curveball and not just bad mechanics. I will make the statement that few kids who throw what really amounts to a "spinner" actually experience arm problems. Please show me evidence to the contrary.

As for my personal philosophy, I teach fastball/change-up low in the strike zone for kids <11.