A little wonder, every day
Why onions make us cry
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The bulbs and roots of spring harvest whole onions on sale at an outdoor farmers' market in Rochester, Minnesota. Original file: [OnionBulbRoots.jpg](https://commons.wikimedia.org/wiki/File%3AOnionBulbRoots.jpg). Creator: Jonathunder. License: CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0). Attribution: Jonathunder. Downloaded from the verified Commons file page; unaltered image. Checked 2026-10-25.
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When a knife damages onion cells, a chemical reaction produces the volatile compound syn-propanethial-S-oxide. It enters the air, irritates the eye, and triggers the tear glands to make tears.
. Creator: Jonathunder. License: CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0). Attribution: Jonathunder. Downloaded from the verified Commons file page; unaltered image. Checked 2026-10-25.](https://xtotam-watt-media-442809139467.s3.eu-central-1.amazonaws.com/facts/be74772a-4c8c-48a2-b3b6-a6951202fc7f/media/122dc16942b7f85c2753262b2dc05f6b5ba195566fd65b822f0dd58d1b0b1fd0/onion-bulb.jpg)
. Creator: Donovan Govan.. License: CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0/). Attribution: Donovan Govan.. Downloaded from the verified Commons file page; unaltered image. Checked 2026-10-25.](https://xtotam-watt-media-442809139467.s3.eu-central-1.amazonaws.com/facts/be74772a-4c8c-48a2-b3b6-a6951202fc7f/media/792711175afb9c0f35cd3dbe7801f1d947cc6f7b07838e0d537fa3a7090ed70a/onion-cut.jpg)