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Short-term toxicity to aquatic invertebrates

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Description of key information

Static freshwater test with Daphnia magna resulted in EC50 of 0.58 mg/L and a NOELR of 0.32 mg/L 

Key value for chemical safety assessment

Additional information

Two experimental investigations are available concerning the acute toxicity to aquatic invertebrates of the test substance was investigated according to OECD Guideline 202 (EU Method C.2). The studies were conducted under certificated GLP compliance and Daphnia magna was used as test organisms, which is a freshwater invertebrate representative of a wide variety of natural habitats, and can therefore be considered as an important non-target organism in freshwater ecosystems. In-house laboratory cultures of the test animals were used, whereby young daphnids, less than 24 h old were used for testing. These daphnids were not individually identified and received no food.

The test concentration to be used in the definitive test of the key study was determined by preliminary range-finding tests (Goodband and Mullee, 2011). Based on these range-finding studies, concentrations of 0.1, 0.18, 0.32, 0.56 and 1.0 mg/L nominal loading rate WAFs were tested. Two duplicates were prepared for each test group, two replicates for the control. No aeration was performed and no evidence of undissolved substance was observed, since Microscopic inspection of the WAFs showed no micro-dispersions or undissolved test item to be present. The solutions were not renewed during the exposure period. The vessels were covered to reduce evaporation and maintained at 21.0 - 22.0 °C in a temperature controlled room with a photoperiod of 16 h light and 8 h darkness with 20 min dawn and dusk transition periods for a test duration of 48 hours. A positive control used potassium dichromate as the reference item at concentrations of 0.32, 0.56, 1.0, 1.8 and 3.2 mg/L was conducted. The EC50 value was determined to be 0.58 mg/L loading rate WAF with 95 % confidence limits of 0.51 - 0 .66 mg/L. The corresponding No Observed Effect Loading Rate (NOELR) is 0.32 mg/L. Gas chromatography (GC) was the analytical method of choice.

Also based on range-finding studies, concentrations of 1.0, 1.8, 3.2, 5.6, 10, 18, 32, 56 and 100 mg/L nominal loading rate WAFs were used in the supporting study (Sewell, 2004). Other test conditions were the same as reported in the key information. In this case, the EC50 value was determined to be 1.3 mg/L loading rate WAF with 95 % confidence limits of 1.0 - 1.8 mg/L. The corresponding No Observed Effect Loading Rate (NOELR) is 1.0 mg/L. No analytical method was used.