As i was talking in earlier post about the effect of propanethiol S-oxide and some other enzyme in the onions which emits tears from your eyes .

_{Info For Onion Criers}

Onions produce the chemical irritant known as syn-propanethial-S-oxide. It stimulates the eyes’ lachrymal glands so they release tears. Scientists used to blame the enzyme allinase for the instability of substances in a cut onion. Recent studies from Japan, however, proved that lachrymatory-factor synthase, (a previously undiscovered enzyme) is the culprit

1. Lachrymatory-factor synthase is released into the air when we cut an onion.
2. The synthase enzyme converts the sulfoxides (amino acids) of the onion into sulfenic acid.
3. The unstable sulfenic acid rearranges itself into syn-ropanethial-S-oxide.
4. Syn-propanethial-S-oxide gets into the air and comes in contact with our eyes. The lachrymal glands become irritated and produces the tears!

BUT recently i found that scientist are working and trying to disarm that crying bomber in a quest against natural tears agonist .

Japanese researcher recently pinpointed the eye-irritating chemical that cut-up onions release: It’s called lachrymatory factor synthase. the researcher says he can eliminate the gene (basic hereditary unit) that creates the tear-jerker chemical–without ruining an onion’s taste….. !!!!!

Good news for cooks, but would it be for the onion? "It’s reasonable to
assume that Mother Nature incorporated the chemical to afford some
protection," says chemist Eric Block at the State University of New
York in Albany.

can they do it .. can’t they . will that have some side effects on humans !?

who know . we’ll just wait and see

Sources [1] [2] [3]