Potassium 1,2-bis(2-ethylhexyloxycarbonyl)ethanesulphonate

Short-term toxicity to aquatic invertebrates

Description of key information

EC50  freshwater invertebrates = 6.6 mg /L. This information is based on read across to the sodium salt of the corresponding substance.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

6.6 mg/L

Additional information

Data are available for the corresponding sodium salt of the substance, docusate sodium. These data are used for read-across to the substance registered.

For the data endpoint “Short-term toxicity to aquatic invertebrates” 2 experimental studies are available: Both are Klimisch 2.

The study from Elementis (Scholz 1993) was classified as Klimisch 2 study. In this study the acute toxicity of formulated product - which contains 64.2% Docusate Sodium, ~ 24% water and ~ 10% ethanol- to Daphnia magna was determined in a static GLP compliant test. The test was performed according to guideline EG 84/449 which is similar to EU method C.2 and OECD 202. The test was started with a control and nominal 2.5, 3.5, 5, 7, 10, 14, 20, 28 and 40 mg formulated product/L corresponding to 0 (control), 1.61, 2.25, 3.21, 4.49, 6.42, 8.99, 12.84, 17.98 and 25.68 mg Docusate Sodium/L. For each test concentration and the control, 4 replicates with 5 daphnids each were set up in 10 mL vessels. The test was performed in darkness. Dose-verification analysis was not performed and hence, the concentrations were reported as nominal concentrations. After 48 hours of exposure, 5, 0, 10, 35, 35, 55, 50, 71, 85 and 100 % of the daphnids were immobilized at 0 (control), 1.61, 2.25, 3.21, 4.49, 6.42, 8.99, 12.84, 17.98 and 25.68 mg Docusate Sodium/L. The corresponding 48 h EC50 value is 6.6 mg Docusate Sodium/L (95% C.I. 5.3 to 8.2 mg Docusate Sodium/L).

The study from Cytec (Goodrich and Lech 1985) was classified as Klimisch 2 study. In this study the acute toxicity of the test substance - which contains 99% Docusate Sodium - to Daphnia magna was determined in a static test. GLP compliance was not stated. The test was performed similar to EEC C.2 and OECD 202. The test was started with a control and nominal 5, 10, 20, 40 and 80 mg test substance /L corresponding to 0 (control), 4.95, 9.9, 19.8, 39.6 and 79.2 mg Docusate Sodium/L. For each test concentration and the control, 4 replicates with 5 daphnids each were set up in 100 mL vessels filled with 80 mL test solution. The test was performed in a 16:8 hour light dark cycle. Dose-verification analysis was not performed and hence, the concentrations were reported as nominal concentrations. After 48 hours of exposure, 0, 0, 0, 5, 60 and 100 % of the daphnids were immobilized at 0 (control), 4.95, 9.9, 19.8, 39.6 and 79.2 mg Docusate Sodium/L. The corresponding 48 h EC50 value is 34.9 mg Docusate Sodium/L. This study is considered to be acceptable for the risk assessment.

The EC50 values of the two Klimisch 2 studies from Scholz (1993) and Goodrich and Lech (1985) were 6.6 and 34.9 mg Docusate Sodium/L, respectively. The evaluation which of the EC50 values is more reliable and relevant for the risk assessment will be made based on (1) the test design, (2) the test material used, and (3) if there is further evidence from disregarded studies with lower Klimisch scores.

(1): Both guideline compliant studies were of comparable quality and hence no decision which study is more relevant could be made based on the test design.

(2): The higher purity of the test material (99% vs. 64%) in the study from Cytec (Goodrich and Lech 1985) when compared to Elementis (Scholz 1993) could indicate that the study from Cytec (Goodrich and Lech 1985) is more relevant. On the other hand, the further constituents of the test material used by Elementis (Scholz 1993) were water (~24%) and ethanol (~10%), both not toxic at 100 mg/L. Therefore, these constituents are not expected to have an effect on the toxicity of the test material.

As worst case the most protective value, the lowest EC50, i. e., the EC50 of 6.6 mg Docusate Sodium/L from Elementis (Scholz 1993) was selected for the further risk assessment for aquatic invertebrates and the CSA.