Dose is everything. The Geneva Convention could not have regulated dosages of chemical weapons - that would not enforceable, nor practical. ...so instead they banned all chemical gases outright.

This does not imply that tear gas is therefor more deadly than the government or the public is aware.

The word "chemical" also doesn't mean "toxic". Water is a chemical, and when riot control measures use water cannons, should we term that "chemical weapons". It's gunpowder a chemical weapon then? What about Uranium. Heck, even a cannon-ball is a chemical weapon.

See what I did there? Using exaggerated terms to advance your agenda just serves to discredit your point.