[esperent]

Why exactly are you trying to compare mustard gas to Tor? I'm kind of lost here.

But anyway, to answer your question: mustard gas is not one thing, it's a class of chemicals. But one of them became the first ever chemotherapy drugs, Mustine:

https://en.m.wikipedia.org/wiki/Chlormethine

[mrits]

Why are you talking about mustard gas chemistry instead of the shells that were brought up?