1,1'-dithiobis[hexahydro-2H-azepin-2-one]

Endpoint summary

Additional information

Toxicity to fish

The acute toxicity to fish of the test substance was investigated according to OECD Guideline 203 and EU Method C.1 in two different experiments.

In the key study, a semi-static freshwater test, rainbow trout (Oncorhynchus mykiss) was chosen as test organisms (Wetton and Mullee, 2001). The substance was tested in concentrations of 1.0, 1.8, 3.2, 5.6 and 10.0 mg/L. The LC50(96h) was determined as 7.5 mg/L with 95 % confidence limits of 5.6 - 10.0 mg/L. The No Observed Effect Concentration (NOEC) was 5.6 mg/L. In a supporting study, zebrafish (Danio rerio) were chosen as test organisms (Rudolf, 2004). 100 % mortality was again recorded at concentrations of 56 and 100 mg/L. After 96 h 71 % mortality was observed at a concentration of 32 mg/L. Due to this observation a second main study was conducted with 0 and 18 mg/L test substance concentration, whereby no mortality was recorded in this case. Seven fish per treatment were used in the main studies. The 96 h results were as followed: LC50: 31 mg/L, LC100: 56 mg/L and the No Observed Effect Loading rate (NOEL) is 18 mg/L.

The computer program ECOSAR v1.00 (EPIWIN software) by US-EPA was used to predict the chronic toxicity towards fish (Chemservice S.A., 2011), resulting in a Chronic Value (ChV) of 158.07 mg/L, thus arising no toxicity concern.

Toxicity to aquatic invertebrates

The acute toxicity to fish of the test substance was tested according to OECD Guideline 202 and EU Method C.2 in a static freshwater test with Daphnia magna as test organisms (Wetton and Mullee, 2001). The EC50(48h) value was determined to be greater than the test concentration of 100 mg/L. The corresponding No Observed Effect Concentration (NOEC) is 100 mg/L.

The prediction for long-term toxicity for aquatic organisms of the test substance was determined by the computer program ECOSAR v1.00 (EPIWIN software) by US-EPA (Chemservice S.A., 2011). For daphnids a Chronic Value (ChV) of 64.00 mg/L was predicted.

Toxicity to aquatic algae

The acute toxicity to aquatic algae of the test substance according to OECD Guideline 201 and EU Method C.3 in a static freshwater test with Desmodesmus subspicatus (former name:Scenedesmus subspicatus) as test organism (Neuhahn, 2011). Analysis of the yield and growth rate of the algal population within 72 h exposure period gave the following results: ErC50(72h) > 100 mg/L and EyC50(72h) > 100 mg/L, as well as NOEC(r) >= 1000 mg/L and NOEC(y) >= 100 mg/L. Effective concentrations correspond to 89.2 % of nominal values at 72 h.

Additionally a prediction for long-term toxicity to green algae was performed with the computer program ECOSAR v1.00 (EPIWIN software) by US-EPA (Chemservice S.A., 2011), resulting in a Chronic Value (ChV) of 70.66 mg/L.

Toxicity to aquatic microorganisms

The acute toxicity to microorganisms of the test substance was investigated according to EC 440/2008 Method C.11, which is equivalent to OECD Guideline 209 (Richter, 2011). After 3 h incubation time the respiration was inhibited for 32.2 % at a test item concentration of 1000 mg/L. The EC50 value (> 1000 mg/L) is calculated from respiration rates at different test item concentrations using the statistics program ToxRatPro Version 2.10 (released 2010 -02 -20).

Toxicity to other aquatic plants and organisms

Toxicity investigations to further aquatic plants and organisms of the test substance were not conducted so far and will not be triggered for a registration under REACH for a tonnage band of 100 - 1000 tons/year. Therefore, no information is provided.