I mostly went with a really huge number to emphasize how even the probably 20-30% ethanol found in mouthwash (that’s a guesstimate, it may actually more or less than that, but I know 40% is around where common hard liquor tends to hover, and I kind of doubt most mouthwash has that much ethanol in it) effects bacterial cells really drastically due to their size, even the amount of alcohol in common wine or even beer is enough to kill a good share of microbes that aren’t specially adapted to be tolerant of alcohol, hence why beer and wine (and equivalents) were the drinks of choice for most people throughout a good portion of history (basically until people started to really figure out the whole water purification thing in the last couple centuries); it was better to be vaguely drunk/hungover all the time than get cholera or dysentery.