Lead Content of Soil, Plants, Foods, Air, and Chinese Herb Formulas

There are growing concerns about Lead is the heaviest of the non-radioactive metals (atomic number 82; atomic weight 207) that naturally occur in substantial quantities in the earth’s surface. Lead is present in all soils, rivers, lakes, and seawater. Despite its weight, lead is also in the air, a component of dust and of sea spray. Lead is present in the proportion of 16 parts per million (ppm) in igneous rocks, the most common ancient rock on the surface, and at an average of about 10 ppm in common soils that are far from sites of contamination; natural soils usually have less than 50 ppm of lead but are never lead free.