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Toxicity to aquatic algae and cyanobacteria

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Description of key information

72 h ErC10: 9.2 mg/L
72 h ErC50: 26 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:
26 mg/L
EC10 or NOEC for freshwater algae:
9.2 mg/L

Additional information

In the Klimisch 2 GLP study from Kimmel (2013) the toxicity of Butanedioic acid, 2(or 3)-sulfo-, 4-[2-[(1-oxo(C12-C18(even numbered) and C18unsaturated)alkyl))amino]ethyl]esters, disodium salts to Desmodesmus subspicatus was determined in a static 72-Hour Algal Growth Inhibition Test. The test was performed according to OECD 201 and EU Method C.3. The nominal concentrations of 3.125, 6.25, 12.5, 25, 50 and 100 mg test item/L (corresponding to1.297, 2.59, 5.19, 10, 21 and 42 mg solid content/L) were tested in parallel with a control. Dose verification analysis was performed. The measured concentrations of the test item in the test media of the test concentrations of 3.125 to 100 mg test item/L (1.297 to 42 mg solid content/L) were between 93 to 111% of the nominal values at the start of the test and between 41 to 72% at the end of the test. Thus, the correct dosing of the test item was confirmed. During the test period of 72 hours, a decrease of test item concentration in the test media occurred. The biological results were related to the mean measured test item concentrations (calculated as the geometric means of the concentrations measured at the start and end of the test), i.e., mean measured 1.1, 2.2, 4.0, 8.4, 16 and 26 mg solid content for nominal concentrations of 1.297, 2.59, 5.19, 10, 21 and 42 mg solid content/L, respectively. In order to determine the growth of the cultures, the cultures were measured with the fluorescent method . The cell density was determined at 0, 24, 48 and 72 hours. The growth of the control cultures fulfilled the validity criteria from OECD 201 (2006). The 72 -hour ErC10 and ErC50 are 9.2 and > 26 mg solid content/L based on the mean measured concentration.

For C12 -MEA (Butanedioic acid, 2(or 3)-sulfo-, 4 -[2 -[(1 -oxododecyl)amino]ethyl] ester, disodium salt) read across was made from the source chemical C12 -C18/C18'-MEA (Butanedioic acid, 2(or 3)-sulfo-, 4-[2-[(1-oxo(C12-C18(even numbered) and C18 unsaturated)alkyl))amino]ethyl]esters, disodium salts). Both substances have the same main C-Chain length of C12 (C12 -MEA 75 -90% C12, C12 -C18/C18'-MEA 45 -55%) . In C12 -MEA the C14 alkyl rest is represented with < 10% while in C12 -C18/C18'-MEA C14 comprises to 15 -20%. This difference is considered small. It can be argued that C12 -MEA is already part of C12 -C18/C18'-MEA. The physical chemical parameters of both substances are similar. Within the N2 subgroup, the toxicity does not show a clear C-Chain dependency, i.e., the EC50/LC50 data for all members of this group are similar. Therefore, read across from C12 -C18/C18'-MEA (source) to C12 -MEA is considered as being justified. 

Based on the data set and the supporting evidence for read across including the similarity of the C-Chain distribution, no further risk assessment factor is needed. The results of this study are considered relevant and reliable for the risk assessment.