Fatty acids, C18 unsaturated, ethyl & methyl esters

Bioaccumulation: aquatic / sediment

Description of key information

Fatty acids, C18 unsaturated, ethyl & methyl esters (EC 941-981-3) has a low bioaccumulation potential.

Additional information

Experimental data investigating the bioaccumulation potential of Fatty acids, C18 unsaturated, ethyl & methyl esters (EC 941-981-3) are not available. The substance components are characterised by a log Pow ≥ 7.8 indicating a potential to bioaccumulate in biota. Estimated bioconcentration (BCF) and bioaccumulation (BAF) values were calculated for the main substance components. The calculations were performed using the BCFBAF v3.01 program (Estimation Programs Interface Suite™ for Microsoft® Windows v 4.11., US EPA), assuming biotransformation (Arnot-Gobas method, including biotransformation, upper trophic). The estimated BCF values range from 25.17 – 310.9 L/kg whereas the calculated BAF is higher. The BAF values range from 603.9 – 4656 L/kg.

However, the information gathered on environmental behaviour and metabolism in combination with the QSAR-estimated BCF values provide enough evidence (in accordance with 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. 1907/2006, Annex IX) to state that the substances is not likely to bioaccumulate. The substance is considered to be readily biodegradable and is insoluble in water (water solubility ≥0.021 mg/L at 25 °C). According to the Guidance on information requirements and chemical safety assessment, Chapter R.7b, readily biodegradable substances can be expected to undergo rapid and ultimate degradation in most environments, including biological Sewage Treatment Plants (STPs). The guidance document states furthermore that once insoluble chemicals enter a standard STP, they will be extensively removed in the primary settling tank and fat trap and thus, only limited amounts will get in contact with activated sludge organisms (ECHA, 2014). Therefore, after passing through conventional STPs, only low concentrations of these substances are likely to be (if at all) released into the environment. If released to the water the substance will tend to bind to sediment and other particulate organic matter due to their hydrophobicity and relatively high adsorption potential. Thus, the most relevant exposure route for aquatic organisms such as fish will be via food ingestion or contact with suspended solids. If the substance is ingested by organisms a fast metabolisation is expected. The substance is 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). 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). 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). The main route of excretion is via expired air as CO2, and the second route of excretion is by biliary excretion and faeces.

According to the Guidance on information requirements and chemical safety assessment, Chapter R.7c (ECHA, 2014), even though ready biodegradability does not per se preclude bioaccumulation potential, generally (depending on exposure and uptake rates) ready biodegradable substances are likely to be rapidly metabolised, and therefore, concentrations stored in aquatic organisms will tend to be low.
Thus, taking all available information on bioaccumulation into account, Fatty acids, C18 unsaturated, ethyl & methyl esters (EC 941-981-3) has a low potential to bioaccumulate.