Well then, you're getting what you want.  You said Roundup isn't diluted enough, and I agreed to further dilution.  You objected to the surfactants in Roundup, and I agreed to diluting glyphosate (not Roundup) with water.  All of your objections have been eliminated.  You claim that glyphosate is low risk, so now all you have to do is to set the time and place for the glyphosate/caffeine challenge.  Remember, it has to be at a public place that is easily accessible.  We'll see if you are willing to stand behind what you are saying or whether you're not.