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Sediment toxicity

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No experimental data evaluating the toxicity to sediment organisms is available for Fatty acids, soya, 2-ethylhexyl esters (CAS 93572-14-6). Since the substance is readily biodegradable, exposure of sediment organisms is unlikely. Furthermore, the substance is not toxic to aquatic organisms up to the limit of water solubility (WS < 0.05 mg/L). In addition, available data indicate, that the substance is not bioaccumulative. Based on the available information, toxicity to sediment organisms is not expected to be of concern.

The substance Fatty acids, soya, 2-ethylhexyl esters (CAS 93572-14-6) is readily biodegradable (76 – 90% biodegradation in 28 days). 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) (ECHA, 2012). Therefore, after passing through conventional STPs, only low concentrations of these substances are likely to be (if at all) released into the environment.
Furthermore, the substance exhibits a log Koc value > 5 and is insoluble in water (< 0.05 mg/L). The Guidance on information requirements and chemical safety assessment, Chapter R7.b (ECHA, 2012) states 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. Nevertheless, once this contact takes place, these substances are expected to be removed from the water column to a significant degree by adsorption to sewage sludge (Guidance on information requirements and chemical safety assessment, Chapter R.7a, (ECHA, 2012)) and the rest will be extensively biodegraded (due to ready biodegradability). Thus, discharged concentrations of these substances into the aqueous/sediment compartment are likely to be negligible.
Considering this information the availability Fatty acids, soya, 2-ethylhexyl esters (CAS 93572-14-6) in the sediment environment can be expected to be generally very low, which reduces the probability of exposure of sediment organisms in general.
Due to the available data on acute and chronic toxicity to aquatic organisms any toxic effects of Fatty acids, soya, 2-ethylhexyl esters (CAS 93572-14-6) to sediment organisms are considered to be unlikely.

Conclusion
Due to its readily biodegradable nature, extensive degradation of this substance in conventional STPs will take place and only low concentrations are expected to be released (if at all) into the environment. Once present in the aquatic compartment, further biodegradation will occur and, due to the high log Kow, low water solubility and high adsorption potential, sediment organisms might be mainly exposed via feed and contact with suspended organic particles. After uptake by sediment species, extensive and fast biotransformation of the substance by carboxylesterases into the free fatty acid and the corresponding alcohol is expected. The supporting BCF/BAF values estimated with the BCFBAF v3.01 program, Arnot-Gobas model including biotransformation, also indicate that this substance will not be bioaccumulative. Furthermore, aquatic toxicity data show that no effects occur up to the limit of water solubility. Therefore, the substance does not pose a risk for sediment organisms in general and testing is thus omitted, hence toxicity to sediment organisms is not expected to be of concern and thus there is no need to investigate further the effects on sediment organisms.