Comparison of Chelating Agents DMPS, DMSA and EDTA for the Diagnosis and Treatment of Chronic Metal Exposure

Abstract

Aims: Several chelating agents are presently used among environmental physicians to diagnose and treat a chronic metal overexposure. We evaluated and compared the binding capacity of the most common chelating agents DMPS (2, 3-dimercapto-1-propanesulfonic acid), DMSA (dimercaptosuccinic acid), also called Succimer) and EDTA (ethylene diamine tetraacetic acid) for the potentially toxic metals Antimony (Sb), Arsenic (As), Cadmium (Cd), Lead (Pb) and Mercury (Hg). Secondly, we evaluated how the nutrient elements Calcium (Ca), Copper (Cu) and Zinc (Zn) are affected by the chelating agents tested. Study Design: Through ICP-MS (Inductively Coupled Plasma Mass Spectroscopy) analysis of urine from environmentally burdened patients, we determined which chelating agent in oral or injectable form has the best potential to be used as a provocation test for the diagnosis of multiple metal over exposure, and which chelating agent is best used for the detoxification treatment of a single metal exposure. Place and Duration of Study: Micro Trace Minerals and Friedle Laboratories, Hersbruck/Regensburg, Germany, between January 2011 and February 2013. Methodology: Data utilized is based on urine samples from chronically exposed patients, male and female adults, received from chelation therapists. Acutely intoxicated patients were not included. Results: The intravenous application of DMPS is most suitable for the diagnosis and treatment of a single or multiple metal exposure, involving the metals Sb, As and Hg. Both EDTAs (NaCaEDTA and NaEDTA), administered intravenously, are the agents of choice for Cd, while Pb can be chelated using DMSA, DMPS, or the EDTAs. Both EDTAs have a strong Zn binding ability, but only NaEDTA is suitable for binding appreciable amounts of Ca. DMPS best binds Cu. Conclusion: The intravenous application of DMPS is most useful for the diagnosis of multiple metal overexposure. It is also the treatment of choice for Sb, As and Hg and has the strongest Cu binding ability of the chelators tested.