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Product Stewardship and Environmental ConsiderationsProduct StewardshipThe Dow Chemical Company has a fundamental concern for all who make, distribute, and use our family of VERSENE* chelating agents, and the environment we share. This concern is the basis for our Product Stewardship philosophy, by which we assess all available information on our products and then take appropriate steps to protect employee and public health and the environment. In addition, Dow is committed to implementing the guiding principles and management practices of the chemical industry's Responsible Care® initiative, which includes Product Stewardship as one of the Management Practices. As part of our Product Stewardship effort, information such as Safety Data Sheets (MSDS/SDS) and the following information are provided to assist our customers in handling our products in a safe and responsible manner. Environmental ConsiderationsThe following questions and answers are extracted from a Position Paper titled "EDTA & the Environment: Questions and Answers," which was prepared by the Detergent Ingredient Review Committee of the Chemical Specialties Manufacturers Association. For a complete copy of the Position Paper, contact:Chemical Specialties Manufacturers Association What levels of EDTA are found in the environment?EDTA levels in drinking water can reasonably be expected to be lower than levels found in the corresponding water sources — lakes, rivers, etc. Studies in Western Europe during the early 1990s showed average EDTA concentrations to be typically less than 25 ppb (mg/L) with a range of <2 ppb to 129 ppb. EDTA concentrations in lakes were found to be <1 ppb to 4 ppb. Levels of EDTA in rivers and lakes have been found to fluctuate depending on seasonal flows. Does EDTA biodegrade in the environment?Yes, but slowly. EDTA does biodegrade, but not rapidly enough to meet current ASTM or OECD criteria for ready or inherent biodegradability (e.g., 80% biodegradation in 28 days). Both biodegradation and photodegradation help insure that EDTA does not persist in the environment. While the overall rate of degradation is too slow to ensure efficient removal during the biological treatment of sewage in municipal waste water treatment, there is a great deal of evidence supporting slow EDTA biodegradation under aerobic conditions in an aquatic environment. The ferric iron, Fe(III), chelate of EDTA photodegrades to biodegradable degradation products. Of the metal chelates of EDTA that do photodegrade, ferric chelate is the most environmentally important one because its photodegradation rate is comparatively high; iron is so abundant in the environment; and ferric iron forms so strong a complex with EDTA compared to most other metals. Does EDTA solubilize heavy metals in the environment?There is no evidence of heavy metal (zinc, copper, nickel, etc.) solubilization at environmentally realistic concentrations. The potential for EDTA to solubilize heavy metals from sediments does exist. Studies have shown that concentrations of EDTA in the 1-100 ppm (mg/L) range, 40-400 times higher than the level of EDTA typically found in the environment, may solubilize metals from sediments. As stated previously, typical realistic environmental concentrations are about 25 ppb (mg/L). Assuming that pH conditions for chelation by EDTA are optimum and no competing complexing agents are present, 25 ppb (mg/L) of EDTA is completely used up by complexation of only 4 ppb (mg/L) of copper or 3.5 ppb of iron or 2.5 ppb of calcium. Scientific evidence does not support occurrence of heavy metal solubilization from sediments into surface waters by EDTA in natural aquatic environments when EDTA is present at molar equivalent concentrations which are below those of heavy metals in solution. One EDTA molecule can only chelate one metal ion. In natural aquatic environments, there is typically a large excess of metal atoms and ions compared to EDTA molecules. Under ideal conditions, there is typically only enough EDTA present to chelate some small fraction of the total metals present. The concentration of dissolved heavy metals in rivers and lakes is affected more by natural or externally induced fluctuations in pH, redox conditions, the presence or precipitating anions, salinity, and the presence of competing sequesterants — both synthetic and naturally occurring (e.g., clays, lignin in woodpulp, humic acids), than by trace amounts of EDTA which may be present.
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