There was recent news article about a child that died because he swallowed two magnets from a toy. Apparently the toy passed the choke hazard test, but he somehow managed to extract the magnets from it.
Thye didn't say what the actual cause of death was. Is it possible that the stomach acid dissolved the magnets and created poisons from the by-products? Are the exoctic materials used in high performance magnets toxic when chemically altered?