Isooctadecyl palmitate

Long-term toxicity to aquatic invertebrates

Description of key information

No effects up to the limit of water solubility (< 0.05 mg/L; OECD 211).

Additional information

Since no studies investigating the long-term toxicity to aquatic invertebrates of isooctadecyl palmitate (CAS 72576-80-8)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 (Z)-octadec-9-enyl oleate (CAS 3687-45-4) and dodecyl oleate (CAS 36078-10-1) was conducted. The read-across substance dodecyl oleate is characterized by a similar fatty acid and fatty alcohol chain length. Dodecyl oleate has a smaller fatty alcohol chain length (C12 compared to C18iso (target)) and a similar fatty acid chain lengths (C18 unsatd. compared to C16 (target)). Therefore, this substance will probably exhibit higher water solubility and bioavailability in the water phase since the water solubility is dependent on the C-chain length of the fatty alcohol and fatty acid (Lide, 2005). However, the water solubility of both substances is still below the detection limit (< 0.05 mg/L). The second read-across substance (Z)-octadec-9-enyl oleate has a similar fatty alcohol (C18:1 compared to C18 iso) and a slightly longer fatty acid chain lengths (C18:1 compared to C16). The use of both read-across substances allows for interpolation to the target substance isooctadecyl palmitate covering the upper and the lower end of chain lengths distribution. 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 first 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 second 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 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 comparable structure, it can be concluded that isooctadecyl palmitate will not exhibit long-term effects on aquatic invertebrates up to the limit of water solubility.