Yes, understand about filtering outor leeching like you describe, but I would imagine any chemicals like added nutes mostly or even those used by the plant that were already in the soil would till reside in the plant even after flushing. And since you would be ingesting that plant those chemicals would be ingested by you. Therefore to have a truly organic grow a person would have to start with a totally chemical free soil, and only fertilize organically, yet still flush.