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Ecotoxicological information

Short-term toxicity to fish

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Description of key information

On a weight of evidence basis, three acute fish toxicity studies of similar reliability support the conclusion that the registered substance is not acutely toxic to fish.  The geometric mean of their results, 96-hr LC50 = 402 mg/L, is carried forward to the risk assessment.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Effect concentration:
402 mg/L

Additional information

Four studies addressing short-term toxicity of the registered substance to fish are presented in the dossier. Three of them investigated the acute toxicity of the registered substance to fathead minnows, all using very similar methodologies, and all performed by either the US EPA Environmental Research Laboratory in Duluth, Minnesota, or by the Center for Lake Superior Environmental Studies, University of Wisconsin-Superior, or a collaboration of both, and are considered in a weight of evidence approach. The fourth study was of short (24-hours) duration, and is therefore not considered in the weight of evidence. The three fathead minnow studies returned 96-hour LC50 values of 786 mg/L, 900 mg/L and 91.7 mg/L. The arithmetical mean of these results is 593 mg/L, and the geometric mean is 402 mg/L. On a weight of evidence basis, these three studies of similar reliability support the conclusion that the registered substance is not acutely toxic to fish. The more conservative geometric mean of the results, 96-hr LC50 = 402 mg/L, is carried forward to the risk assessment.

Short-term toxicity to fish.001 – fathead minnow – 1985a: Acute toxicity to the freshwater fish Pimephales promelas (Fathead minnow) was assessed by the US EPA Environmental Research Laboratory, Duluth, Minnesota. Using proportional diluters and flow through conditions, duplicate groups of 10 fish were exposed to a range of concentrations for 96 hours. Test concentrations were analyzed daily, and the corrected (for recovery efficiency) average results were <10 (control), 131, 210, 382, 594 and 1044 mg/L. Throughout the study, temperature was maintained at 24.9 °C (SD 0.52), pH at 7.75 (SD 0.16), and dissolved oxygen at 7.3 mg/L (SD 0.13). A range of behavioural parameters were assessed and the number of mortalities (including controls) was recorded at 0, 12, 24, 48, 72 and 96 hours. The 96 hour LC50 was reported to be 786 mg/L, and a 96 hour EC50 based on behaviour (loss of schooling behaviour, swimming near surface, hypoactive and under-reactive to external stimuli, and loss of equilibrium prior to death) was reported to be 476 mg/L.

Short-term toxicity to fish.002 – fathead minnow – 1985b: Acute toxicity to the freshwater fish Pimephales promelas (Fathead minnow) was assessed by the US EPA Environmental Research Laboratory, Duluth, Minnesota / Center for Lake Superior Environmental Studies, University of Wisconsin – Superior, according to ASTM 1980 standard procedure not according to GLP (pre-dates GLP). The fish were exposed to the substance under flow-through conditions for 96 hours. Throughout the study, temperature was maintained at 25.0 ± 0.5 °C, pH at 7.6 ± 0.2, and dissolved oxygen at >= 80% saturation. The 96- hour LC50 was determined to be 900 mg/L.

Short-term toxicity to fish.003 – fathead minnow–1983: Acute toxicity to the freshwater fish Pimephales promelas (Fathead minnow) was assessed by the US EPA Environmental Research Laboratory, Duluth, Minnesota according to the methods defined by the US Environmental Protection Agency Committee on Methods for Toxicity Tests with Aquatic Organisms not according to GLP (pre-dates GLP requirements). The study was conducted under flow through conditions under the use of proportional diluters with 4 fish per concentration (individual test concentrations not reported) for 96 hours. Temperature was maintained at 25 ±1 °C and the concentrations were measured in each tank throughout the test. The percentage of dead fish was recorded at 1, 3, 6, 12, 24, 48, 72 and 96 hours. The following validity criteria were met: dissolved oxygen concentrations remained above 60% of the air saturation value at the end of the test; and the pH of the control and of the test solution did not vary by more than one unit during the course of the test. Mortality of the controls was not reported and although concentrations were measured throughout the test, individual nominal and measured concentrations were not reported. The 96 hour LC50 was reported to be 91.7 mg/L.

Short-term toxicity to fish.004 – Goldfish – 1973: Acute toxicity to the freshwater fish Carassius auratus (Goldfish) was assessed using a method equivalent or similar to OECD guideline 203 (Fish, acute toxicity test) not according GLP (pre-dates GLP). The fish were exposed to the substance under static conditions for 24 hours.  The median tolerance limit (TLm: the concentration at which 50% animals survive) at 24 hours was reported to be 380 mg/L. Detailed information was not provided in the report, and it is not included in the weight of evidence due to its short duration.