We all know the feeling of us having teary eyes when we are slicing onions, we should know that it is not caused by any emotions, rather they are just reflex tears that are caused by exposure to irritants in our eyes.
According to healtline.com, onions are bulbs that grow underground and some animals feed on them, to prevent this, onions are built with a defense mechanism that protects them from being eaten by these pest.
To mitigate such incoming threats, when an onion bulb is cut open, it releases enzymes and sulfenic acid, these two compound mix together to produce what is known as propanethial S-oxide, which is an irritating gas.
This Propanethial S-oxide is a lachrymatory agent, which means that it can cause tears, when it comes in contact with the eyes, by turning into what is known as sulfuric acid, when it then comes in contact with the watery layer that protects the human eyeballs.
Our eyes also come with a defense mechanism that helps to protect the eye from incoming threats, this is why when the nerves in our eyes detect any form of lachrymatory agent they start producing tears, to flush it out, so next time you experience it, you should know it’s just just your eyes trying to defend itself against the lachrymatory agent.