From BBC News: Button batteries pose ‘deadly’ risk to toddlers
If accidentally swallowed, the small, round batteries can get lodged in the oesophagus and burn a hole through its lining.
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Surgeon Kate Cross said: “Button batteries should be treated like poison and kept out of reach of children.”
Deena says
My child stuck one up his nose and it burned a hole in his septum. We knew right away and went straight to the ER so it was only in a couple of hours. Bh it healed on its own. But please take this warning seriously.