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Description of key information

3h-NOEC 640 mg/l (FeNaEDTA.3H2O) respiration inhibition for activated sludge

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
640 mg/L

Additional information

An activated sludge respiration inhibition test was performed with the test substance FeNaEDTA.3H2O in accordance with OECD Test Guideline 209, and in compliance with the OECD principles of Good Laboratory Practice (Geurts 2010; reliability 1, KEY study). After a contact duration of 3 hours, no inhibition of the respiration of the activated sludge was measured up to the highest concentration tested, i.e. 640 mg/L. Thus the test substance is considered not harmful to activated sludge.

In a published study the acute toxicity (15min-EC50) of Fe(III)-EDTA towards Photobacterium phosphoreum was investigated using the Microtox Toxicity Analyzer according to the protocol provided by the supplier (Sillanpaa Oikari 1996). The 15min-EC50 was found to 88.4 mg test material per liter (210 µmol/l, with a 95%CL of 154 - 286 µmol/l). The reliability was classified as Rel. 2 as details of the methods and results are lacking, including some details on the substance identity. Moreover, it is questionable whether there is no interference of the salt water with the Fe-EDTA-complex that would influence the exposure concentrations or the results.

The key study was selected as this one was carried out according to the guidelines and it tests the required object (activated sludge).

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