Fatty acids, C16-18 and C18-unsatd., 2-ethylhexyl esters

Toxicity to aquatic algae and cyanobacteria

Description of key information

No effects on toxcity to aquatic algae up to the limit of water solubility.

Additional information

No studies on effects of Fatty acids, C16-18 and C18-unsatd., 2-ethylhexyl esters (CAS 85049-37-2) on freshwater algae are available. The assessment was therefore based on studies conducted with the category members 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. Grouping of substance and read across approach. Further justification is given within the endpoint summary 6.1 and within the category justification section 13. In this case of read-across, the best suited (highest degree of structural similarity, nearest physico-chemical properties) read-across substance was entered into IUCLID. Nevertheless, as can be seen in the data matrix of the category justification in Section 13, all reliable data in the category support the hazard assessment for this endpoint, by showing a consistent pattern of results.

 

The toxicity of the substance 2 -ethylhexyl oleate (CAS 26399-02-0) to the freshwater algae Scenedesmus subspicatus was 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 for 72h (Rieche 1995). The testing with a nominal concentration of 100 mg/L without removal of insoluble particles resulted in a mean inhibition of algal growth rate and biomass of 38.3 % and 75.1%, respectively. No effects were observed after removal of insoluble particles 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.

To substantiate the findings, a further key study as read-across from Fatty acids, C8 -16, 2-ethylhexyl esters (CAS 135800-37-2) with Scendesmus subspicatus was taken into account (Wierich 1998). The test was performed according to EU-Method C.3 with filtered and unfiltered solution of 100 mg/L. The filtered solution showed no significant inhibition of algae growth or growth rate which means that the water soluble part of the test substance turned out not to be toxic. With a more or less homogenous emulsion of test material high inhibitions of algae growth and growth rate were observed (75.7% and 42.6% respectively). This observed inhibition in presence of undissolved test substance can be accounted to physical, but not biological influences and a ErC50(72h) of > 100 mg/L could be stated.

As supporting study the marine algae Skeletonema costatum was tested according to ISO 10253 (WAF-test). The resulting ErL50(72 h) was determined as 281.4 mg/L (nominal loading rate, Hudson 2000).

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, C16 -18 and C18 unsatd., 2 -ethylhexyl esters (CAS 85049 -37 -2).