SOME MEDICINAL PLANTS OR CROPS have a high bioaccumulation capacity so that small traces of METALS IN THE WATER AND IN THE SOIL can result in high concentrations in the harvested crop.
Heavy metal & pesticides residue doses are toxic to humans and highly regulated in crops-derived products, especially those developed for the PHARMACEUTICAL INDUSTRY.
For this reason, metal traces should be minimized in order to meet quality requirements and PROTECT HEALTH of consumers. Additionally, metals can also generate poisoning in the plant affecting your SOIL  & your farm PRODUCTIVITY.