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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Primarily studies with equimolar EDTA vs essential nutrients shall be considered to conclude on toxicity rather than that depletion inhibits growth. The studies of BASF & AkzoNobel with the EDTA-Fe complex can be considered appropriate as well as the study by Geurts (2009). Geurts (2009) study is the preferred (key) information based on measured concentrations and the most conservative EC10 value when expressed as EDTA-CuNa2. Concentrations in that study were reported as EDTA-MnNa2. A recalculation to EDTA-CuNa2 using MW ratio would give an EC10 of 397.3/389.13 x 42.8 = 43.7  mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
662.6 mg/L
EC10 or NOEC for freshwater algae:
43.7 mg/L

Additional information

Multiple algae tests (Scenedesmus subspicatus, Scenedesmus quadricauda, Pseudokirchneriella subcapitata) with different EDTA salts and complexes have been performed. As chelating agent, available EDTA will interact with essential micro and macro nutrients to the growth of algae. If a surplus of EDTA is present, it will cause depletion of nutrients thus growth inhibition, as shown in the results from Dufkova (1984), BASF (1995, 2x), AkzoNobel (2001), Kean (2009 & 2009 1-5) and Geurts (2009).