Ethyl decanoate

Endpoint summary

Description of key information

Ethyl decanoate as the category members, is considered as not bioaccumulable based on the estimated BCF ≤ 105.7 L/kg whole body w.w. calculated with the BCFWin program (methods based on log Kow and on Arnot-Gobas model). Moreover on the basis of the available litterature, Ethyl decanoate ingested through food is quickly hydrolysed by lipases, and the resulting free decanoic acid is metabolized by beta-oxydation pathways to generate energy for the cells or reconstituted into glyceride esters and stored in the fat depots in the body of mammals. The beta-oxydation process which allows the metabolisation of fatty acids, takes place in mitochondries and/or peroxysomes and it represents a very common metabolic pathway in numerous organisms, like mammals, fish, mussels and algae.

Ethyl decanoate is rapidly metabolized and does not pose a risk to living organisms in regard to bioaccumulation and biomagnification.

Additional information

Ethyl decanoate and the category members are poorly soluble in water (< 1 mg/L), show moderate adsorption (log Koc = 2.85) and are readily biodegradable. As a consequence they are eliminated to a high extent in sewage treatment plants, and their aqueous environmental concentrations are assumed to be low.

For the fraction released into the aquatic environment, the concentration in the water phase will be reduced by rapid biodegradation and mainly by potential of adsorption to solid particles and to sediment. Due to low exposure concentrations through water, no significant uptake through the water phase is expected.

Food ingestion is likely the main uptake route of the category members into fish, since the substances may adsorb to solid particles, which could be potentially ingested by fish. Also for sediment-dwelling organisms the main uptake route will be ingestion of contaminated sediment. In the case of ingestion, category members are predicted to undergo metabolism. Esters of primary alcohols, containing from 1 to 18 carbon atoms, with fatty acids, containing from 2 to 18 carbon atoms, have been shown to be hydrolysed by pancreatic lipases in a study by Mattson and Volpenhein (Mattson and Volpenhein, 1972). Measured rates of enzyme catalysed hydrolysis varied between 2 and 5 μeq/min/mg enzyme for the different chain lengths (IUCLID section 7.1.1, Mattson and Volpenhein, 1972; and references therein).

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, 2001; HSDB).

Fatty acids are either metabolized 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).

Peroxisomal β-oxidation has also been shown to take place in fish, mussels and algae (Rocha et al., 2003; and references therein; Frøyland et al., 2000; Bilbao et al., 2009; Winkler et al., 1988).

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).

Studies conducted with rats indicate that the main route of excretion in rats is via expired air as CO2, and the second route of excretion is by biliary excretion and faeces. Exemplarily, experimental data of ethyl oleate (the ethyl ester of oleic acid) support this assumption: 14C-labeled carbon of 5 mL/kg of ethyl oleate (CAS No. 111-62-6) was rapidly excreted in respiration CO2 (approximately 70%), faeces (7 -10%), and urine (1-2%), with essentially complete elimination by 72 hours after administration (Bookstaff, 2003).

In conclusion, the category members will be mainly taken up by ingestion and are digested through common metabolic pathways, providing a valuable energy source for the organism, as dietary fats.

These substances are thus not expected to bioaccumulate in aquatic or sediment organisms.

Biomagnification are processes that may occur once a chemical is bioaccumulated along the food chain. As these chemical substances are readily biodegradable and are considered to be rapidly metabolized, the category members will not be biomagnified within the food chain.

Hence, as the category members do not pose a risk to organisms in regard to bioaccumulation/biomagnification, in addition to reasons of animal welfare, no further testing is neither required nor proposed. The available literature, supporting the assessment of bioaccumulation are presented in the IUCLID technical dossier and associated chemical safety report in a Weight of Evidence (WoE) approach, which is in accordance to the REACh Regulation (EC) No 1907/2006, Annex XI General rules for adaptation of the standard testing regime set out in Annexes VII to X, 1.2, to cover the data requirements of Regulation (EC) No. 1907/2007 Annex IX and X (ECHA guidance section R.7.11.5.3, page 121).