2-ethylhexyl nonanoate

Endpoint summary

Additional information

Experimental data investigating the toxicity of 2-ethylhexanol nonanoate (CAS 59587-44-9) are not available. The aassessment was therefore based on a read across to a study conducted with short chain fatty acid ester isopropyl myristate (CAS 110-27-0) on to the earthworm Eisenia fetida .No mortality was observed during the 14-day exposure period at the test concentration of 20,000 mg/kg. Additionally, data on the toxicity to plants is available for for the analogue substance Fatty acids, C16-18 and C18-unsaturated, 2-ethylhexyl esters (CAS 85049-37-2). The 21-day NOEC value is determined to be 100 mg/kg for all plants tested, and EC50 values between 390 and 600 mg/kg are reported.

Based on the available data the terrestrial toxicity of 2-ethylhexanol nonanoate (CAS 59587-44-9) is expected to be low. The target and the source substance are poorly soluble in water (< 0.05 mg/L L), have high adsorption potential (Koc ≥ 3) and a high log Kow (> 4), their behaviour in the terrestrial compartment is expected to be similar. Furthermore, the target and the source substance are expected to be metabolised by organisms after ingestion, which is considered to be the main uptake route. Esters of primary alcohols, containing from 1 to 18 carbon atoms, with fatty acids, containing from 2 to 18 carbon atoms, have shown to be hydrolysed by pancreatic lipases in a study by Mattson and Volpenhein (Mattson and Volpenhein, 1972; and references therein). Measured rates of enzyme catalysed hydrolysis varied between 2 and 5 µeq/min/mg enzyme for the different chain lengths. the target and the source substance 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, 2011). 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). For fatty acids up to C22, beta-oxidation generally takes place in the mitochondria, resulting in the final product acetyl-CoA, which directly enters the citric acids cycle (Berg, 2002). Beta-oxidation of longer fatty acids takes place in the peroxisomes and is incomplete (Reddy and Hashimoto, 2001; Singh et al., 1987; Le Borgne and Demarquoy, 2012; and references therein). It gives 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). Plants and most fungi harbour the beta-oxidation cycle only in the peroxisomes (Poirier, 2006).

Based on the available data , toxicity of 2-ethylhexanol nonanoate (CAS 59587-44-9) to terrestrial organisms is not expected to be of concern, and consequently, no further testing is proposed.