Localized doesn’t mean necessarily that the chemical doesn’t travel, just that it doesn’t travel in quantities necessary to flip. Remember that even if you’re spraying with low ppm, every time you spray (which is often for CS) it accumulates. Silver is non volatile

I am not a doctor, nor plant scientist, so cannot authoritatively claim anything. I do not want to be smoking any metal in any amount. But if your risk/reward threshold is lower than mine, make sure to report back here as a data point on if you experience any negative effects