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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

With high probability acute not harmful to aquatic algae

Key value for chemical safety assessment

Additional information

The lowest effect value of cyclohexanone on algae is described in a publication by Brack and Rottler (1994). A 72h-EC50 of 32.9 mg/L based on biomass was determined. However the methodology is not guideline conform, such as the test organism Chlamydomonas reinhardtii is not a guideline standard organism according to OECD 201. Therefore the study was not taken into account for classification.


Brack and Rottler compared the effect on Chlamydomonas reinhardtii with the effect caused on standard algae Scenedesmus subspicatus. Therefore they refer results from a publication of Bringmann and Kühn (1978). For the standard test organism Scenedesmus subspicatus Bringmann and Kühn (1978) determined a TT (Threshold Toxicity comparable to EC10) of 370 mg/L after 192 h exposition. The study was considered as valid with restrictions, since no analytical measurements conducted. Furthermore the test duration of 8 days is unusual long, with the consequence that exponential growth at the end of the test is unlikely. Nevertheless the obtained result may be considered as supportive information for determining the low toxicity of cyclohexanone on algae.


Finally the 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 %. Therefore volatilisation can be excluded under this test conditions. After 72 hours exposition to cyclopentanone no effect on Scenedesmus subspicatus was observed up to the highest test concentration of 100 mg/L.