Chelation therapy is used to removal Heavy Metals from the body. The two substances used are DMSA and EDTA. DMSA is predominantly used orally and is considered more gentle. It also has a greater affinity for metals such as Mercury. EDTA is usually given through intravenous therapy and is considered a stronger chelater. It tends to have an affinity for Lead. While both substances chelate all metals, your Naturopathic Doctor will help you to determine which will be best indicated for you case and which is the safest to do. How much and which heavy metals you need to calculate will be based in urine element testing.