As with any toy, you should always supervise your bird and know how your bird will react to the toy before assuming it will be safe for your bird. Every bird is different and the natural curiosity of all parrots can get them into some very interesting predicaments, but knowing your own bird can help a great deal. What might be safe for one bird may not be safe for another as well.
For more information on toy safety and the use of zinc in bird toys, TNT Bird Toys would like to offer the following web sites:
Testing for Zinc in Parrot Toys, Play Gyms, and Cages, by Ed Harris
Playing it Safe with Bird Toys