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Short-term toxicity to aquatic invertebrates

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Description of key information

No effects up to the limit of water solubility based on available data (OECD 202; EU Method C.2).

Key value for chemical safety assessment

Additional information

Since no studies investigating the short-term toxicity to aquatic invertebrates of Fatty acids, C16-18, C16-18-alkyl esters (CAS 97404-33-6) are available for this endpoint, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read across to the structurally related category members 2-ethylhexyl oleate (CAS 26399-02-0) andFatty acids, C16-18, C12-18-alkyl esters (CAS 95912-87-1)was conducted.

Compared to Fatty acids, C16-18, C16-18-alkyl esters, the read-across substance 2-ethylhexyl oleate is characterized by a similar fatty acid component (C18:1 compared to C16-18 (target)) and a similar fatty alcohol moiety (2-ethylhexanol compared to C16-C18 (target)). The smaller alcohol chain length increases the water solubility and therefore the bioavailability in the water. Water solubility is negatively correlated with the C-chain length of the fatty alcohol and fatty acid (Lide, 2005). Therefore, it is possible to extrapolate from a category member with higher water solubility since it has an increased bioavailability in the water phase (ECHA, 2008). The second read-across substanceFatty acids, C16-18, C12-18-alkyl esters is characterized by the same fatty acid chain lengths (C16-C18). Moreover, the fatty alcohol component is similar to the target substance (C12/14/16/18 compared to C16-C18 (target)).

This read-across is justified in detail in the overall summary (IUCLID chapter 6.1) and within the category justification in IUCLID Section 13. In this case of read-across, the best suited (highest degree of structural similarity, nearest physico-chemical properties) read-across substance was used for the assessment. Nevertheless, as it can be seen in the data matrix of the category justification in section 13 and the overall summary, all reliable data in the category support the hazard assessment of each category member by showing a consistent pattern of results.

The study with the read-across substance 2-ethylhexyl oleate (CAS 26399-02-0) was performed according to EU Method C.2 under GLP conditions (Küch&Wierich, 1995). Daphnia magna was exposed to a limit concentration of 100 mg/L for 48 h. Insoluble particles of the test substance were separated before initiation of the study. No immobilization was recorded at the end of the study resulting in an EC50 (48 h) of > 100 mg/L (nominal).

The second study with the read-across substance Fatty acids, C16-18, C12-18-alkyl esters (CAS 95912-87-1) was performed according to EU Method C.2 (GLP) under static conditions with the water flea Daphnia magna (Wierich, 2001). A Water Accommodated Fraction of nominal 100 mg/L was tested in this study. Measured concentrations were in the range of 0.1 - 0.2 mg/L or even below the detection limit (GC analysis). After 48 h no effects on the test organisms were observed resulting in an EL50 > 100 mg/L. Thus, it can be concluded that no toxicological effects on aquatic invertebrates are expected up to the limit of water solubility for fatty acids, C16-18, C12-18-alkyl esters.

Based on the result from two structurally related read-across substances (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) which are characterized by a similar ecotoxicological profile and comparable structure, it can be concluded that Fatty acids, C16-18, C16-18-alkyl esters will not exhibit short-term effects to aquatic invertebrates up to the limit of water solubility.