Fatty acids, lanolin, iso-Pr esters

Short-term toxicity to aquatic invertebrates

Description of key information

No effects up to the limit of water solubility for Daphnia magna (EU Method C.2)

Additional information

No studies on short-term toxicity to aquatic invertebrates are available for Fatty acids, lanolin, isopropyl esters (CAS 63393-93-1), which contains fatty acids from C10 to C29. Studies are available for isopropyl esters with C14, C16 and C18:1 fatty acids (CAS Nos. 110-27-0, 142-91-6, 112-11-8), covering a large part of the constituents of Fatty acids, lanolin, isopropyl esters. An aquatic invertebrate study is also available for the similar category member Fatty acids, C16-18 and C18 unsaturated, isobutyl esters (CAS No. 84988-79-4). All tested substances are practically insoluble in water, and no effects were observed in any of the studies. Since the metabolism of Fatty acids, lanolin, isopropyl esters is not assumed to significantly differ from the shorter fatty acid alcohol esters. All fatty acid alcohol esters are expected to be hydrolysed by lipases (Mattson and Volpenhein, 1972; and references therein). The resulting free fatty acids and alcohols are absorbed from the intestine into the blood stream. Fatty acids are either metabolised via the β-oxidation pathway in order to generate energy for the cell or reconstituted into glyceride esters and stored in the fat depots in the body. The reactions involved in the β-oxidation are slightly different for very long chain fatty acids (greater than C22). Whereas β-oxidation generally takes place in the mitochondria, very long chain fatty acids are oxidised in peroxisomes by slightly different enzymatic reactions (Reddy and Hashimoto, 2001; Singh et al., 1987; Le Borgne and Demarquoy, 2012; and references therein).Enzymes of the peroxisomalβ-oxidation pathway have also been found in mussels (Bilbao et al., 2009).The final product of β-oxidation in mitochondria is acetyl-CoA, which directly enters the citric acids cycle (Berg, 2002). In peroxisomes, the reaction is incomplete giving rise to medium chain acyl-CoA, which are then taken in charge by the carnitine octanoyl transferase and converted into acyl-carnitine that can leave the peroxisome and, at least for some of them, may be fully oxidized in the mitochondria (Le Borgne and Demarquoy, 2012; and references therein). Consequently, despite the differences in fatty acid metabolism, Fatty acids, lanolin, isopropyl esters (CAS 63393-93-1), can be fully metabolised by aquatic organisms and is thus not expected to differ from the rest of the category in terms of toxicity to aquatic organisms. A read-across approach to other category members is therefore justified. Sincewater solubility is expected to be even lower, the tested substances represent a worst case compared to Fatty acids, lanolin, isopropyl esters. Since a conducting a fish test with Fatty acids, lanolin, isopropyl esters would most likely lead to ambiguous results, due to methodological difficulties caused by low water solubility, a read-across approach, using the available data, is considered the most reliable way to assess the short-term toxicity of the substance to aquatic organisms. This read across approach 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 in Section 13.

The key study with isopropyl myristate (CAS No. 110-27-0) was performed as a limit test according to EU Method C.2 and GLP (Stelter, 1995). The test organism Daphnia magna was exposed to the test substance in a static system for 48 hours. Three different methods were used for the preparation of test solutions: 1) direct addition to 100 mg/L, 2) direct addition to 100 mg/L with removal of undissolved test substance and 3) 3-5 times saturation without separation of undissolved material. With the first method an oil film was observed at the surface, and up to 100% immobilisation occurred. With the other two methods, no significant effect was observed. Based on the results, the observed immobilisation is most probably due to physical effects caused by undissolved test substance. It can therefore be concluded that the test substance had no significant toxic effect on the test organism up to the limit of water solubility. An EC50 of > 0.05 mg/L was reported.

The key study with isopropyl palmitate (CAS No. 142-91-6), used as key study, was performed according to EU Method C.2 and GLP (Kirch, 1998). The test organism Daphnia magna was exposed to the test substance in a static system for 48 hours, at nominal test concentrations of 1000 and 3000 mg/L (measured initial concentrations 0.72 and 1.68 mg/L). No mortalities were observed at any of the test concentrations, and an EC50 of > 3000 mg/L was reported.

The key study conducted with Fatty acids, C16-18 and C18-unsaturated isobutyl esters (CAS No. 84988-79-4) was performed as a limit test according to EU guideline 92/69/EWG and GLP (Wierich, 1995). The test organism Daphnia magna was exposed to the test substance in a static system for 48 hours. Three different methods were applied for the preparation of test solutions: 1) direct addition to nominal 100 mg/L without separation of undissolved test material, 2) direct addition to nominal 100 mg/L followed by a separation of undissolved test material and 3) 3 to 5 fold saturation concentration without separation of undissolved material. Immobilisation was observed only in the test solutions prepared using the first method, and was therefore probably due to physical effects caused by the large amount of undissolved test material present in the test solution. With separation of undissolved test material and with 3 to 5 fold saturation no negative effects were observed. It can be concluded that the test substance had no toxic effects on Daphnia magna up to the limit of water solubility. An EL50 of > 100 mg/L is reported.

The supporting study with isopropyl oleate (CAS No. 112-11-8) was performed according to the guideline AEP2 issued by the Ministry of Agriculture, Fisheries and Food of the United Kingdom (1984) (Clitherow, 1991). The marine test organism Crangon crangon was exposed to the test substance in a static system for 48 hours, at nominal test concentrations of 850, 1530, 2640, 4760 and 8500 mg/L. No mortality was observed at any of the test concentrations, and the LC50 was determined to be > 8500 mg/L.

Thus, based on theabove mentioned results, and due to the structural and profile similarities of the substances, as are explained within the overall endpoint summary 6.1 it can be concluded that no toxicological effects on aquatic invertebrates are expected up tothe limit ofwater solubility for Fatty acids, lanolin, isopropyl esters (CAS 63393-93-1).