shrooom, as i understand it, AS is "additive free", but not chemical free. i'm not sure any commercial plants can really be chemical free. AS *does* have an organic version available too, so perhaps that might be an option you'd be willing to consider? you'd probably have to have a local tobacconist special order the organic version for you (or perhaps find it online).
personally, i'm off tobacco
& using a personal vaporiser/e-cigarette myself, and i make my own e-juice, so i know exactly what i'm putting into it. i feel it helps, but who really knows, as i'm not exactly certain what goes into the food-grade flavorings i use to flavor my juice. heh. but, plenty of people avoid that by just vaping their nicotine
unflavored. can't really get any fewer "chemicals" than medical-grade nicotine & propylene glycol! but that's moving too far off-topic, so i'll just mention again that you can get organic American Spirit tobacco & leave it at that.