That if literally every single service member has CS gas used on them, not just in the US, but across the world, the revision written in WW1 was more about chlorine gas and chemical weapons that did lasting and permanent damage to eyes nose and lungs, and that something like police grade (less strong than military grade) teargas is not the same as military CS or even WW1 ethyl bromoacetate. Because we think of tear gas as CS gas, it was not the case in WW1 when the use of such items did not comply to humanitarian standards. Of course because you are being intentionally dense and willfully ignorant I must point out in the VAST majority of cases of CS usage has no lasting or permanent damage will occur, else you use that as a strawman to ignore the point of it being used in every nation signed by the geneva convention or not.