Never give to children under age 4. Any toy with small, removable parts is a choking hazard for kids under age 3. Their shininess makes them a natural target for small kids' curious hands and mouths. Don't leave loose change or a purse within the reach of kids 3 and younger. An uninflated balloon or pieces of a popped balloon can easily be swallowed or inhaled.
Latex balloons are especially lethal because the material completely obstructs airways.
Never let kids under age 6 play with balloons, uninflated or inflated, without supervision. If either type pops, dispose of all the pieces immediately. These are easily popped into little mouths and swallowed. Keep away entirely from any child 3 or younger. If ingested, battery acid can damage digestive tract.