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Short-term toxicity to aquatic invertebrates

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Description of key information

An 48-h EC50 value of 100 mg/L HBF4 is used for assessment.

Key value for chemical safety assessment

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A GLP-compliant OECD 202 guideline study is available for toxicity in aquatic invertebrates (Daphnia magna) for the HBF4 structural analogue KBF4. In this combined limit/range-finding test 20 daphnids per concentration (4 vessels, 5 daphnia per vessel) were exposed to a control and a nominal KBF4 concentration of 100 mg/L in the limit test. In the range finding test 10 daphnids per concentration (2 vessels, 5 per vessel) were exposed to concentrations of 0.10, 1.0 and 10 mg/L. At the start and the end of the 48-hour test period, the nominal concentration of 100 mg/L from the limit test was analytically verified. At t=0 and t=48, measured concentrations were determined at 92 and 86% relative to nominal, respectively. Therefore, the test substance was considered to be stable throughout the test and all results were based on nominal concentrations. No significant effects on mobility of daphnids was observed in any of the concentrations tested. The 48-h EC50 value was >100 mg/L which, after correction for molecular weight, is equivalent to a 48 -h EC50 of >70 mg/L HBF4. However, as in this study no effects were seen at any of the concentrations tested and furthermore in the additional test with the HBF4 structural analogue NaBF4 much higher effects concentrations were observed (see below), his molecular weight correction is considered unproportional for purposes of risk assessment and classification and labeling. Therefore, the critical effect value of HBF4 for aquatic invertebrates is maintained at 100 mg/L.

In addition, a study on the short-term toxicity to aquatic invertebrates was performed with the HBF4 chemical analogue NaBF4. In this study, Daphnia magna were exposed to NaBF4 concentrations ranging from 1 to 10000 mg/L for 48 hours under static conditions. The number of living and dead neonates was noted at 24 and 48 h after the initiation of each trial. Neonates observed as motionless and without a discernable heartbeat were considered to be dead. Based on the immobilisation findings, the 48-h EC50 was determined at 4766 mg/L. When corrected for molecular weight, the 48-h EC50 for HBF4 is 3811 mg/L.