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Toxicity to aquatic algae and cyanobacteria

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Description of key information

No toxic effects on aquatic algae up to the limit of water solubility, read across.

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Data on the short-term toxicity of Fatty acids, soya, 2-ethylhexyl esters (CAS 93572-14-6) to aquatic algae are not available. The assessment was therefore based on studies conducted with the structurally similar substances 2-ethylhexyl oleate (CAS 26399-02-0) and Fatty acids, C8-16, 2-ethylhexyl esters (CAS 135800-37-2), as part of a read across approach, which is in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5. Further justification is given within the overall summary chapter 6.1 and within the analogue justification section 13.
The effects of 2-ethylhexyl oleate (CAS 26399-02-0) to the freshwater algae Scenedesmus subspicatus were investigated according to the EU-method C.3 considering the VCI concept draft for the acute testing of poorly soluble substances from 1994-01-31 (Rieche 1995). Two test solutions with a substance concentration of 100 mg/L (nominal) were prepared. The first solution was not filtered and contained insoluble particles of the test substance. The second solution was filtered and thus undissolved test substance was removed. After an exposure period of 72 the algal growth rate was reduced by 38.3% and the algal biomass was reduced by 75.1% in the unfiltered test solution. No effect on the growth rate and an increase of algal biomass by 23.1% was observed in the filtered test solution. It can be assumed that the inhibition of algal growth in the unfiltered solution was due to physical effects and not to systemic toxicity. Therefore an ErC50(72h) of > 100 mg/L was reported.
The toxicity of Fatty acids, C8-16, 2-ethylhexyl esters (CAS 135800-37-2) to Scendesmus subspicatus was investigated in a study following to EU-Method C.3 with filtered and unfiltered test solutions of 100 mg/L nominal substance concentration (Wierich, 1998). No significant inhibition of algae growth or growth rate was observed in the filtered solution. In the unfiltered solution an inhibition of 75.7% regarding algal growth and of 42.6% regarding algal biomass was recorded. Thus, the observed inhibition was related to physical effects and an ErC50(72 h) of > 100 mg/L was determined.
Thus, based on the above mentioned result, and due to the structural and profile similarities of the substances, as are explained with in the overall endpoint summary 6.1 it can be concluded that no toxicological effects on algae are expected up to the limit of water solubility for Fatty acids, soya, 2-ethylhexyl esters (CAS 93572-14-6).