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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

Fatty acids, C8-10, octyl estrs does not bioaccumulate in organisms.

Key value for chemical safety assessment

Additional information

No experimental data investigating the bioaccumulation potential of Fatty acids, C8-10, octyl esters are available. Therefore, all available related data are combined in a Weight of Evidence (WoE), 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).

Bioaccumulation refers to uptake of a substance from all environmental sources including water, food and sediment. However, the accumulation of a substance in an organism is determined, not only by uptake, but also by distribution, metabolism and excretion. Accumulation takes place if the substance is taken up faster than it can be metabolised and/or excreted.

In the case of Fatty acids, C8-10, octyl esters uptake of dissolved substance via water is expected to be low, since the substance is poorly water soluble, has high adsorption potential and is regarded as readily biodegradable. The aqueous environmental concentration of the substance is assumed to be low, as the substance is to a high extent eliminated in sewage treatment plants before entering the environment. If fractions of this chemical were to be released in the aquatic environment, the concentration in the water phase will be reduced by rapid biodegradation and potential of adsorption to solid particles and to sediment. Additionally, the substance has estimated low potential for dermal absorption. QSAR estimations, taking molecular weight, log Pow and water solubility into account, resulted in a dermal absorption of 1.21 – 5.52 cm/h for the main components of Fatty acids, C8-10, octyl esters (DERMWIN v2.00, 2015). Due to low exposure concentration through water and low dermal absorption potential, no significant uptake through the water phase is therefore to be expected.

Food ingestion is likely to be the main uptake route of Fatty acids, C8-10, octyl esters in fish, since the substance adsorbs to solid particles, which could be ingested by fish. Also for sediment-dwelling organisms the main uptake route will be ingestion of contaminated sediment. In the case of ingestion, Fatty acids, C8-10, octyl esters is 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 (1969). Measured rates of enzyme catalysed hydrolysis varied between 2 and 5 µeq/min/mg enzyme for different chain lengths (Mattson and Volpenhein 1969). 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 (e.g., Berg et al. 2002). 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. 2002). 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, Fatty acids, C8-10, octyl esters 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.

Biotransformation and biomagnification are processes that may occur once a chemical has bioaccumulated. As Fatty acids, C8-10, octyl esters is readily biodegradable and is considered to be rapidly metabolised, the substance will not biomagnify through the food chain. 

Hence, Fatty acids, C8-10, octyl esters 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).

 

References

Berg JM, Tymoczko JL, Stryer L. 2002. Biochemistry, 5thedition, W.H. Freeman and Company

Mattson FH, Volpenhein RA. 1969. Relative rates of hydrolysis by rat pancreatic lipase of esters of C2-C18 fatty acids with C1-C18 primary n-alcohols, J Lipid Res 10: 271-276

Tocher DR. 2003. Metabolism and functions of lipids and fatty acids in teleost fish. Rev Fisheries Sci 11(2): 107-184