2-ethylhexyl nonanoate

Endpoint summary

Additional information

Experimental data for the target substance 2-ethylhexyl nonanoate (CAS 59587-44-9) are not available. Therefore, the source substances Fatty acids, C8-16, 2-ethylhexyl esters (CAS 135800-37-2), Isopropyl myristate (110-27-0) and Octyl octanoate (CAS 2306-88-9) were selected to cover the aquatic toxicity endpoints.
In accordance with Regulation (EC) No 1907/2006, Annex XI, 1.5, grouping and read-across, the target substance and all source substances are not considered to be harmful to aquatic organisms based on the results from short-term studies with fish, aquatic invertebrates and aquatic algae. Moreover, long-term studies with aquatic invertebrates did not result in any long-term effects on reproduction. The available short-term toxicity studies (fish, Daphnia, algae) did not demonstrate any toxicity of the analogue substances to aquatic organisms up to the limit of water solubility.

Short-term toxicity to fish: The assessment of the acute toxicity of the target substance 2-ethylhexanol nonanoate (CAS 59587-44-9) is based on a read across the structurally most similar analogue source substance Fatty acids, C8-16, 2-ethylhexyl esters (CAS 135800-37-2). Mortality or symptoms of intoxication of fish were not observed and thus a LC50 (96h) > 10000 mg/L based on the nominal substance concentration was reported.
The assessment of the acute toxicity of 2-ethylhexanol nonanoate (CAS 59587-44-9) to aquatic invertebrates is based on a read across the structurally analogue source substance Fatty acids, C8-16, 2-ethylhexyl esters (CAS 135800-37-2). The study on the acute toxicity of the substance to Daphnia magna was conducted with filtered test solutions. No immobilisation of the Daphnids was observed and thus EC50 (48h) > 100 mg/L was determined.
The assessment of the acute toxicity of 2-ethylhexanol nonanoate (CAS 59587-44-9) is based on a read across the structurally most similar analogue source substances Fatty acids, C8-16, 2-ethylhexyl esters (CAS 135800-37-2) and Octyl octanoate (CAS 2306-88-9). Both studies were conducted with Desmodesmus subspicatus and reported no toxicological effects on aquatic algae up to the limit of water solubility of the substances.
Long term toxicity to fish: Data on the long-term toxicity to fish are not available for any of the analogue substances. However, short-term studies available for fish, daphnia and algae, all indicate a low potential for aquatic toxicity. Moreover, the reliable NOECs obtained from algal growth studies and daphnia reproduction studies are all above the limit of water solubility. Additionally, the aquatic concentrations of these substances are expected to be very low. This assumption of low environmental exposure is based primarily on the lack of water solubility and also on the fact that all substances are readily biodegradable and have high adsorption potential (log Koc 3.89 – 4.9 MCI method, KOCWIN v2.00), and are thus expected to be eliminated in sewage treatment plants to a high extent. In the aquatic environment, the concentration in the water phase will be reduced by biodegradation and adsorption to solid particles and to sediment. If exposure would occur, food ingestion is likely to be the main uptake route of the analogue substances in fish, since the substances will be adsorbed to solid particles potentially ingested by fish. In the case of ingestion, the analogue substances are predicted to undergo metabolism. Studies on rats demonstrated that esters of primary alcohols, containing from 1 to 18 carbon atoms, with fatty acids, containing from 2 to 18 carbon atoms, are hydrolysed by pancreatic lipases. Measured rates of enzyme catalysed hydrolysis varied between 2 and 5 µeq/min/mg enzyme for the different chain lengths (Mattson and Volpenhein, 1972; and references therein). The esters are thus expected to be hydrolysed by lipases. The resulting free fatty acids and alcohols are absorbed from the intestine into the blood stream. The alcohols are metabolised primarily in the liver through a series of oxidative steps, finally yielding carbon dioxide (Berg et al., 2001; HSDB). Fatty acids are either metabolised via the beta-oxidation pathway in order to generate energy for the cell or reconstituted into glyceride esters and stored in the fat depots in the body (Berg et al., 2001). Metabolic pathways in fish are generally similar to those in mammals. Lipids and their constituents, fatty acids, are in particularly a major organic constituent of fish and play major roles as sources of metabolic energy (Tocher, 2003).
In conclusion, the analogue substances will be mainly taken up by ingestion and digested through common metabolic pathways, providing a valuable energy source for the organism, as dietary fats. Long-term toxic effects on fish are therefore not to be expected.
Long term toxicity to aquatic invertebrates: The assessment of long-term toxicity of 2-ethylhexanol nonanoate (CAS 59587-44-9) to aquatic invertebrates is based on a study conducted with the analogue substance isopropyl myristate (CAS No. 110-27-0). The study demonstrated that the test substance had no effect on the reproduction or mortality of the test organisms.
Toxicity to microorganisms: The assessment of the toxicity of 2-ethylhexanol nonanoate (CAS 59587-44-9) is based on a read across to the analogue substance Octyl octanoate (CAS 2306-88-9).

Overall, it can be concluded that the target substance 2-ethylhexanol nonanoate (CAS 59587-44-9) is not toxic to aquatic organisms up to the limit of water solubility, based on the results from a suitable source substance.