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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

With high probability the test substance is acutely not harmful to aquatic algae.

Key value for chemical safety assessment

EC50 for freshwater algae:
300 mg/L

Additional information

For the hazard assessment on green algae several guideline compliant studies have been performed using Na4-EDTA, FeNa -EDTA and Fe(III)EDTA, for justification for read-across see IUCLID 5, Chapter 13.

According to BASF 94/1080/60/1 an inhibitory effect of the test substance was shown, which was caused by complexing essential micronutrients from the culture medium. Therefore algae growth can be significantly reduced under standardized guideline conditions and may yield apparent results that are more or less severe than the true toxicity (see Guidance on Hazard to the Aquatic Environment Globally Harmonized System GHS Annex 9 A9.3.3.4, 2007). To compensate this secondary effect, the algae study with Scenedesmus subspicatus was performed once in nutrient- enriched media with FeCl3 (BASF, 95/9999/60/1). Finally the EC50 (72h) for the growth rate was determined to be nominal > 100 mg/L. as no analytical dose verification was performed. The 72 hour EC50 value for Fe(III)EDTA with P.subcapitata was greater than 100 mg/L based on nominal concentrations and greater than 60 mg/L based on the mean measured concentrations (Akzo Nobel 2001). Further on, the toxicity of FeNa-EDTA was tested in standard OECD medium. The calculated EC50 of nominal > 1000 mg/L FeNa-EDTA were based on range finding test with a broad range (Akzo Nobel 2009).

The results of these four studies indicates that the predicted LC50 for EDTA (acid form) and its salts are higher than measured 60 mg/L and can be estimated to be higher than 300 mg/L, which is in line with the EU Risk Assessment (2004).