My parents also wouldn't let me wear contacts until I was 12. And believe me, with the thickness of my glasses, it was torture. I didn't like that they made me wait. However, I understand now that they didn't think I was ready to take responsibility for them prior to that. That is the biggest issue, and a question about your child that only you can answer.
Do you think your child is responsible enough to take care of her contacts? As I'm sure you know, it's a pretty big responsibility to handle them properly, clean them, etc. If they don't take proper care of them, it can cost you more money than is necessary and possibly harm their eyes.
As for whether or not children can wear them, sure. Talk to her eye doctor and see what he/she recommends. If he/she feels that contacts would be a good fit for your daughter, then go forward with deciding if she's responsible enough to take care of them.
Here's a good article about children and contacts.
http://www.allaboutvision.com/parents/contacts.htm
Good luck with your decision! Hope this helped!