Registration Dossier

Ecotoxicological information

Short-term toxicity to fish

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

Semi-static freshwater test with Rainbow trout (Oncorhynchus mykiss) resulted in LL50 of 0.75 mg/L and a NOELR of 0.56 mg/L 

Key value for chemical safety assessment

Additional information

Concerning acute toxicity to fish two experimental results are available which can be concerned as reliable without restrictions (Klimisch 1). The test material was tested according to OECD Guideline 203 (EU Method C.1) with certificated GLP compliance. Rainbow trout (Oncorhynchus mykiss) were used as test organisms in both cases, which is a freshwater fish representative of a wide variety of natural habitats, and can therefore be considered as an important non-target organism in freshwater ecosystems. Water Accomodated Fractions (WAFs) were prepared due to the low water solubility and complex nature of the test material. The acclimatisation period of the juvenile fish was conducted for 12 days. The stock fish were fed commercial trout pellets which was discontinued 24 h prior to the start of the definitive test. There was no mortality in the 7 days prior to the start of the test and the fish had a mean standard length of 4.4 cm (SD = 0.2) and a mean weight of 1.00 g (SD = 0.22) at the end of the definitive test. At the start of the test 10 fish were placed in each test vessel at random, giving a loading rate of 0.5 g bodyweight/L.The test concentration to be used in the definitive test was determined by a preliminary range-finding test. Based on this Range-finding study, the substance was tested in concentrations of 0.32, 0.56, 1.0, 1.8 and 3.2 mg/L, whereby the amounts of test material were each seperately added to a glass vial and approximately 15 mL of diluent added. The vials were then swirled to bring the test material to the surface and dispersed onto the surface of 21 litres of dechlorinated tap water to give the loading rates respectively. The experiment was performed at 14.0 °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 period of 96 h. The test vessels were aerated via narrow bore glass tubes. A semi-static test regime was employed in the test involving a daily renewal of the test preparations to ensure test concentrations of soluble components of the test material were maintained over the test and to prevent the build up of nitrogenous waste products. The water temperature, pH and dissolved oxygen concentrations were recorded daily throughout the test. All sample preparations were observed to be clear, colourless solutions throughout the test. The control group was maintained under identical test conditions but not exposed to the test material. No abnormalities as well as no dead fish were detected in this group. The same results were reported for the test concentrations of 0.1 and 1 mg/L loading rate throughout the Range-finding test.

In the key study, some sub-lethal effects such as increased pigmentation and loss of equilibrium of exposure were observed at the test concentration of 3.2 and 10 mg/L after 6 h exposure period were observed (Sewell, 2004). At the time point of 24 h all fish were dead. Considering the definitive test, the highest loading rate resulting in 0% mortality was determined to be 0.56 mg/L loading rate WAF, the lowest loading rate resulting in 100% mortality to be 1.0 mg/L loading rate WAF. The LL50 was determined as 0.75 mg/L with 95 % confidence limits of 0.56 - 1.0 mg/L. The No Observed Effect Loading Rate (NOELR) was sought to be 0.56 mg/L loading rate WAF.

In the supporting study, at the the time point of 24 h all fish were dead testing the nominal loading rate of 10 mg/L. Considering the definitive test, the highest loading rate resulting in 0 % mortality was determined to be 0.32 mg/L loading rate WAF, the lowest loading rate resulting in 100 % mortality to be 1.0 mg/L loading rate WAF after 48 h. The LL50 was determined as 0.42 mg/L with 95 % confidence limits of 0.32 - 0.56 mg/L. The No Observed Effect Loading Rate (NOELR) was thought to be 0.32 mg/L loading rate WAF.