Fatty acids, C16-18, C12-18-alkyl esters

Long-term toxicity to aquatic invertebrates

Description of key information

No effects up to the limit of water solubility (OECD 211; OECD 202, part 2)

Additional information

Since no studies investigating the long-term toxicity to aquatic invertebrates of fatty acids, C16-18, C12-18-alkyl esters (CAS 95912-87-1)are available for this endpoint, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read across to the three structurally related category members 2-ethylhexyl oleate (CAS 26399-02-0), dodecyl oleate (CAS 36078-10-1) and (Z)-octadec-9-enyl oleate (CAS 3687-45-4) was conducted. Since the UVCB substance fatty acids, C16-18, C12-18-alkyl esters is very variable regarding its composition, a read-across to three well-defined mono-constituent substances covering the variability of the substance was conducted. All read-across substances are characterized by the same fatty acid component (C18 unsatd.) esterified with C8-, C12- and C18 unsatd.-alcohol components, respectively. This read-across is justified in detail in the overall summary (IUCLID Section 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 was performed according to OECD 202, part 2 (1993) under GLP conditions (Küch, 1995). Daphnia magna was exposed to two nominal concentrations (1 and 100 mg/L) which were both measured to be < 0.01 mg/L indicating similar concentrations in both test vessels. Effects to Daphnia magna were observed after 21 d with 90% mortality (on day 19) at 100 mg/L and no effects at 1 mg/L. The authors stated, that the mortality in the higher concentration could be attributed to sample contamination. 23% reduction of reproduction in the 100 mg/L sample occurred after 21 d, whereas no effects were observed at 1 mg/L resulting in a NOEC (21 d) ≥ 1 mg/L. The nominal concentration of 100 mg/L was not taken into account for the assessment due to the possible contamination of test solutions.

The second study with the read-across substance dodecyl oleate (CAS 36078-10-1) was performed according to OECD 211 under GLP conditions with the water flea Daphnia magna (Brunswik-Titze, 2013). Five nominal concentrations up to 100 mg/L were tested in a semi-static exposure system as Water Accommodated Fractions (WAF). No effects on the reproduction of D. magna were observed after 21 d. One dead animal was recorded at 50 mg/L but it was reported that it was no substance specific effect (accident during medium change). Therefore, a NOELR (21 d) of ≥ 100 mg/L (nominal) was derived. The chemical analysis resulted in concentrations below the analytical detection limit of 0.005 mg/L reflecting the very low water solubility of the test item.

The third study with the read-across substance (Z)-octadec-9-enyl oleate (CAS 3687-45-4) was performed according to OECD 211 with the water flea Daphnia magna under semi-static conditions (Höger, 2013). Due to the very low water solubility (< 0.05 mg/L) a limit test with a Water Accommodated Fraction (WAF) of nominal 100 mg/L was performed. No effects on reproduction and mortality were recorded after 21 d resulting in a NOELR (21 d) of ≥ 100 mg/L. 0% mortality was recorded in the control whereas 5% mortality was observed in the treatment. This mortality is regarded as natural and tolerated by the test guideline. The chemical analysis resulted in concentrations below the analytical detection limit of 0.0423 mg/L reflecting the very low water solubility of the test item.

Based on the available result from three 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, C12-18-alkyl esters will not exhibit long-term effects on aquatic invertebrates up to the limit of water solubility.