"What he was proposing to use in Mesopotamia was lachrymatory gas, which is essentially tear gas, not mustard gas."

So in theory, if you block the lachrymatory factor synthase, you can increase thiosulfinate, and end up with a tearless, yet more tasty, onion!

With an unobserved hint to the affected lady, he pushed an empty dish towards her as a lachrymatory, in order that nothing might be lost.