Acetic acid, oxo-, sodium salt, reaction products with ethylenediamine and hydroxybenzenesulfonic acid monosodium salt, iron sodium salts

Toxicity to microorganisms

Description of key information

Fe(3K)EDDHSA (EC 462-490-6), activated sludge, OECD 209: EC50(3h) > 100 mg/L 
Fe(Na)EDDHA (CAS 84539-55-9), activated sludge, OECD 209: EC10(3h): 450 mg/L, EC50(3h) > 1000 mg/L

Key value for chemical safety assessment

EC50 for microorganisms:

100 mg/L

EC10 or NOEC for microorganisms:

450 mg/L

Additional information

Toxicological effects towards aquatic microorganisms of Fe(3Na)EDDHSA (CAS 84539-54-8) were not investigated experimentally. Read across to the structurally similar substances Fe(3K)EDDHSA (EC 4462-490-6) and Fe(Na)EDDHA (CAS 84539-55-9) was performed to fulfill this relevant endpoint under REACH (for further details, please refer to the separate read-across statement).

The acute toxicity to microorganisms of Fe(3K)EDDHSA (EC 462-490-6) was investigated according to OECD Guideline 209 (L´Haridon, 2000). The inoculum was taken from the aeration tank of a predominantly domestic sewage treatment plant (WTP of Petit-Quevilly, France). The substance was tested in the concentrations of 1, 3.16, 10, 31.6 and 100 mg/L with an aeration rate of 0.5 - 1 L/min. The temperature was held between 20 - 21°C at the pH range of 6 - 8. The mentioned test concentrations, as well as two controls and three reference concentrations (3,5 -Dichlorophenol) were set up with inoculum at 1.6 g/L. After 3 h incubation time the respiration was inhibited for 0 % even at the highest test concentration of 100 mg/L. Therefore, the EC50(3h) is greater than 100 mg/L and the test substance is considered as non-toxic for microorganisms in waste water treatment plants. The reference substance resulted in an 3-h EC50 value of 13.2 mg/L with 95 % confidence limits of 11 - 16 mg/L.

The toxicity of Fe(Na)EDDHA (CAS 84539-55-9) towards freshwater microorganisms was investigated in accordance to OECD Guideline 209 / EU Method C11 (BASF SE, 2009). Activated sludge was collected from the aeration tank at a municipal wastewater treatment. Aliquots of the stock solutions with test- or reference substance were pipetted into test vessels and made up with demineralized water to a volume of 150 mL. After that 8 mL synthetic medium were given to the test vessel. To prepare the blank control assays 150 mL of demineralized water and 8 mL synthetic medium were given to the blank control test vessels. The pH-values were measured in all test vessels. An adjustment was not necessary. 42 mL demineralized water were added to each test vessel. After addition of 50 mL of the inoculum suspension (dry weight 7.5 g/L) the incubation was started by aeration of the test vessels with pressure air. The vessels for the blank control assays were prepared according to the same procedure without addition of test- or reference item. After 180 minutes incubation the mixtures in the test vessels were placed subsequently into a closed oxygen measuring cell. As results, an EC50(3h) and EC80(3h) > 1000 mg/L and an EC10(3h): 450 mg/L is reported.