Here’s to the tears that onions cause

Onions make us teary because a reaction in the onion releases a chemical called lachrymatory factor, or LF, that irritates the eyes. The onion’s cells break open, allowing two normally separated substances to combine. Linked together, they become a potent chemical weapon.

“It hits your eyes, and then it hits your sensory nerves in your eyes and causes them to tear up,” said Josie Silvaroli, an undergraduate at Case Western Reserve University in Cleveland who helped describe the process in the July issue of the journal ACS Chemical Biology. “It’s similar to tear gas.”

There are some options to avoiding tears: Chuck your onion in the fridge before cutting it, or submerge it in water while chopping.