I will get back to you soon. No, dry ice is just carbon dioxide, the same stuff used to make soda pop carbonated. It's just in frozen form. Breathing an atmosphere containing a high level of carbon dioxide is harmful, but unless you lock the kids in a sealed safe with the dry ice punch it's fine. The dry ice in the punch is not poisonous.
Dry ice is solid carbon dioxide.
It provides a bit of carbonation, just like in pop. The bubbles in pop are also carbon dioxide. The danger of course, would be to ingest a piece. The sugar is dissolved in the water, the flavoring stirred in and then the broken up dry ice is added. Dry ice, even encapsulated in frozen punch, is quite cold and could stick to a child's tongue or roof of the mouth, causing a nasty freeze burn.