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Environmental fate & pathways

Endpoint summary

Administrative data

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EDTA is not found to be readily biodegradable according to OECD criteria. In standard OECD 301D ready biodegradability tests with natural river water as inoculum it was shown that EDTA complexes with a stability constant lower than 10E14 like EDTA-Na4, EDTA-CaNa2, EDTA-MgNa2 etc. less than 60% biodegradation was observed after 28 days indicating that these substances should indeed not be classified as readily biodegradable. In these same tests however > 60% biodegradation was observed when these tests are prolonged to day 60 (Ginkel, 2018) indicating that these compexes, having stability constants < 10E14, are ultimately biodegradable and should be classified as "not persistent". EDTA-CaNa2 has a stability constant < 10E14 and is therefore under the conditions applied considered to be inherently biodegradable fulfilling specific criteria.

Complexes with a stability constant >= 10E14 like EDTA-CuX complexes (where X stands for K2, Na2 or (NH4)2) should be considered "Completely and inherently biodegradable". The dissociation rates are however considered too low to allow classification as not persistent.

 

Based on the estimated log Kow (<3) and available BCF study in fish with radiolabelled EDTA (BCF range 1.1-1.8) it can be concluded there is low potential for bioaccumulation for EDTA-CuK2.

 

The estimated log Koc value for EDTA-CuK2 is 1.7 (worst case). This is less than the threshold value of 3 indicating no adsorbing potential for this compound.

 

Due to high water solubility and low adsorption, EDTA will eventually leach to ground- and surface waters and not accumulate in soil. Due to pH fluctuations in surface water, moderate substitution rates and the combined photodegradation and biodegradation, all EDTA salts will eventually disappear from surface water.