as far as the raidoactivity and heavymetals go it it is present in a lot of liquid fertilizers and is just as much a problem in the hydroponic solutions used in grow ops. Organised crime funds most of the comercial pot production in north america. I highly doubt these guy are making thier own organic teas to fertilize the plants. they are useing chemical fertilizers to get the plants big fast. They care as little about your health as the tabacco companies.
Its all about the money