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Toxicity to aquatic algae and cyanobacteria

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Description of key information

No effects up to the limit of water solubility.

Key value for chemical safety assessment

Additional information

In general, no intrinsic effects among the members of the SCAE C2 -C8 category towards algae were observed. All EC50(72h) values were above the limit of water solubility. Physical effects caused by the test substance were described in presence of undissolved test material.

The effects of 2-ethylhexyl oleate (CAS 26399 -02 -0) to the freshwater algae Scenedesmus subspicatus were investigated in the key study (Rieche 1995). The study was performed according to the EU-method C.3 considering the VCI concept draft for the acute testing of poorly soluble substances from 1994-01-31 for 72 h. The testing with a nominal concentration of 100 mg/L without removal of insoluble particles resulted in a mean inhibition of the algal growth rate and biomass of 38.3% and 75.1%, respectively. No effects were observed after removal of insoluble particles (filtration of the test solution) on algal growth rate, only a biomass stimulation of 23.1 % was stated. It can be assumed that undissolved particles inhibited the algal growth due to physical effects and not to systemic toxicity. Therefore an ErC50(72h) of > 100 mg/L can be stated implying that no effect could be observed up to the limit of the water solubility.

As supporting study, a read across from Fatty acids, C16-18 and C18-unsatd., 2-ethylhexyl esters (CAS: 85049-37-2) was used. In this test, the marine algae Skeletonema costatum was tested according to ISO 10253 (WAF-test). The resulting ErL50(72h) was determined as 281.4 mg/L (nominal loading rate, Hudson 2000).