Fatty acids, lanolin, iso-Pr esters

Toxicity to aquatic algae and cyanobacteria

Description of key information

No toxic effects up to the limit of water solubility for Scenedesmus subspicatus (DIN 38412, Part 9)

Additional information

There are no studies on algal toxicity available for Fatty acids, lanolin, isopropyl esters (CAS No. 63393-93-1), which contains fatty acids from C10 to C29. Data on algal toxicity is available for the structurally similar category members isopropyl myristate (CAS No. 110-27-0) and Fatty acids, C16-18 and C18 unsaturated isobutyl esters (CAS No. 84988-79-4). The longer fatty acids possibly present in Fatty acids, lanolin, isopropyl esters are expected to be less soluble in water than the tested substances, and are thus considered as a worst case approach for assessing the toxicity of Fatty acids, lanolin, isopropyl esters. Its metabolism is not expected to significantly differ from the tested substances. 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 algae (Winkler et al., 1988).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 algal toxicity of the substance. 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 the EU Method C.3 and GLP (Rieche, 1995). The test organism Scenedesmus subspicatus was exposed to the test substance in a static system for 72 hours, at the nominal test concentration of 100 mg/L. The test was performed with and without separation of undissolved test substance. With undissolved test substance present, algal growth was significantly inhibited. However, when the undissolved phase was separated, no effects on growth were observed. It can, therefore, be concluded that the substance has no toxic effects on the test organism up to the limit of water solubility.

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 the EU guideline 92/69/EWG and GLP (Berger, 1995). The test organism Scenedesmus subspicatus was exposed to the test substance in a static system for 72 hours, at the nominal test concentration 100 mg/L. The test was performed with and without separation of undissolved test material. With undissolved test substance present, algal growth was significantly inhibited. However, when the undissolved phase was separated, no effects on growth were observed. The inhibition can be thus regarded as associated physical effects caused by the undissolved material present. It can be concluded that the substance has no toxic effects on test organism up to the limit of water solubility.

Thus, based on theabove mentioned results, 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 tothe limit ofwater solubility for Fatty acids, lanolin, isopropyl esters (CAS No. 63393-93-1).