Based on the available environmental assessment data, methylglycine N,N-diacetic acid, trisodium salt (MGDA·Na3) does not cause significant environmental pollution and is widely recognized as a readily biodegradable, environmentally friendly chelating agent. Its core environmental advantage lies in its rapid and thorough biodegradability and low aquatic toxicity, and it does not contain phosphorus, thus avoiding water eutrophication issues.
Core Environmental Data
Readily Biodegradable: This is its most prominent environmental feature. Under various OECD standard test conditions, MGDA can rapidly and substantially degrade. For example, in the OECD 301B test, degradation reaches 90%~100% by day 28; in the OECD 301F test, degradation reaches 88% by day 28. It is classified as a “readily biodegradable” substance.
Low Aquatic Toxicity: Toxicological tests on aquatic organisms such as fish, Daphnia, and algae show that its toxicity endpoint values (such as EC50/LC50) typically exceed 100 mg/L, indicating that it is not toxic to these organisms under test concentrations.
Low Environmental Persistence: Unlike traditional chelating agents such as EDTA, MGDA has lower complex stability with metals, allowing it to dissociate more readily in wastewater systems, thereby promoting microbial degradation and reducing environmental persistence.
Supplementary Notes
Although MGDA itself has good environmental properties, its environmental fate as a chelating agent also depends on the stability of the metal complexes it forms. Under certain specific conditions (such as when forming stable complexes with certain heavy metals), its degradation rate may be affected. However, overall, its environmental performance is significantly superior to that of non-biodegradable chelating agents such as EDTA and phosphates.