• Question: Why do we cry whilst cutting onions?

    Asked by Gabriele to Ben, Francis, Max on 15 Mar 2018.
    • Photo: Ben Mulhearn

      Ben Mulhearn answered on 15 Mar 2018:

      I’m not quite sure what the chemical is in onions, but it stimulates or tear glands to produce tears, that’s why it also stings a little. Onions do this to protect themselves in the wild from things that might want to eat them such as insects and other small animals.

    • Photo: Francis Man

      Francis Man answered on 15 Mar 2018:

      Onions contain molecules that have double bonds and disulfide bonds, for example allicin and diallyl disulfide. They’re quite reactive and volatile, so they reach the eyes easily and irritate the nerve cells.

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