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Short-term toxicity to aquatic invertebrates

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Description of key information

With high probability acute not harmful to aquatic invertebrates

Key value for chemical safety assessment

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Two publications by Bringmann and Kuehn (1982, 1977) indicate that cyclohexanone is acute not harmful to Daphnia. The 24h-EC50 values are 800 mg/L and 820 mg/L, respectively. Both studies were performed similar to German industrial standard, with a test period of 24 h and without analytical controls. Nevertheless these limitations were considered in a validity score of 2 (valid with restrictions), which is in the line with the validation in the ICCA SIDS program. The validity without analytical monitoring is reasonable, since cyclohexanone can be supposed as stable under the test conditions and the volatilization of cyclohexanone is negligible. Cyclohexanone has a Henry’s Law constant of 1.3 Pa/m³ mol and has therefore a low tendency to escape from the awter phase.

These results are confirmed by a read across to the structural analogue substance cyclopentanone. For cyclopentanone a GLP guideline study with analytical controls is available (L'Haridon, 2003). At the end of the test duration the recovery rate of the test item was > 80 %. Cyclopentanone has an estimated Henry`s Law constant of 0.92 Pa/m³ mol. Therefore volatilisation can be excluded under this test conditions. After 48 hours exposition to cyclopentanone no immobilisation of Daphnia magna was observed up to the highest test concentration of 100 mg/L.