Diseases?

I guess I'm just a paranoid sumbitch but one of the dumbass theories I've always held onto was that plants will "filter out" as they grow resulting in a pure form except for chemicals that have been put on their leaves, like insecticides, etc. But really I'm not so sure. The only way to really tell that filtering thing is if some chemical, alien to the plants natural environment, is introduced while it's growing, then found in the harvested product. Does anyone know if any experiment like that has ever been done? I just watched the noon news about people gettin Alzheimers and Parkinsons from some environmental crap they were exposed to years ago. I'm wondering about the nutes we use, especially in veg. Everybody wants a healthy yield but I'm sure most would take less if they were assured they wouldn't be ingesting chemicals from nutes.

Crap, I meant to put this in "Organics." Maybe a mod could move it for me? I don't think I'm sposta post twice.