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Short-term toxicity to fish

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Description of key information

The water solubility of the test substance is very low. The test media were analysed for iron content in order to demonstrate equilibration and stability of iron potassium oxide during the tests. Throughout the test no dissolved iron was detected at or above the Iimit of determination of 0.1 mg/L at the single loading rate of 1000 mg/L. No mortality or any other effects were noted in rainbow trout exposed for 96 hours to a WAF prepared at a loading rate of 1000 mg/L. Therefore, an LC50 value cannot be reliably determined from the test. According to REACH guidance R7a (Appendix  7.8-1) for substances that show no effect at the limit of solubility, and for which all reasonable efforts were made to obtain and maintain the highest possible concentration over the whole test duration, the limit value is to be used for risk assessment. As these criteria were met, the 96-h LC50 for fish is determined at >1.0 mg/L (limit of solubility).

Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Effect concentration:
1 mg/L

Additional information

Acute toxicity to fish of the test substance was determined in a limit test performed according to the OECD guideline 203 and in compliance with GLP criteria. As the test substance was sparingly soluble in water, a water accommodated fraction was produced using a loading rate of 1000 mg/L. Rainbow trout (7 per concentration) were exposed to the test medium and a control for 96 hours under semi-static conditions. Samples for analysis of the actual concentration were taken every 24 hours (just before and just after renewal of test media). At the loading rate of 1000 mg/L, analytical concentrations of dissolved iron were below the Iimit of detection (0.1 mg/L) in all except one of the fresh and aged test solutions (a value of 0.1 mg/L was measured in the fresh test medium on the first day). The concentrations of suspended iron ranged from 0.88- 2.3 mg/L in the freshly prepared solutions and from 0.30- 0.63 mg/L in the aged solutions as a result of a fine film of test compound coating the bottom of the test vessel.In the exposure group one fish showed minor toxic effects until 72 hours after exposure. At 96 hours these signs were no longer observed. No mortalities occurred. Based on these findings the LC50 is determined at > 1000 mg/L (based on the loading rate).