What is the safest stuffing for baby toys?

I hand-make lots of hats, blankets, pillows, and other hand-made items. I've recently been crocheting a stuffed toy for a baby. I normally fill the things I make with poly-fill (polyester filling) but I'm not sure if it's safe enough to fill a baby toy. What is the safest stuffing I can use to make a baby toy? Is poly-fill suitable or should I buy something else?