Dodecyl oleate

Sediment toxicity

Description of key information

Taking all available information into account the LCAE category members are unlikely to pose a risk for sediment organisms and testing is thus omitted.

Additional information

No experimental data evaluating the toxicity to sediment organisms are available for the LCAE category members.Only negligible releases into surface waters from sewage treatment plants are expected to take place due to: a) the ready biodegradability and b) the high adsorption properties of this substance, resulting in an effective removal in sewage treatment plants. Therefore chronic exposure of sediment organisms is unlikely.Furthermore, the substance is not toxic to aquatic organisms up to the limit of water solubility. In addition, available data indicate, that the LCAE category members are not bioaccumulative. Based on the available information, toxicity to sediment organisms is not expected to be of concern.

Intrinsic properties and fate

All LCAE category members are readily biodegradable. 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, 2012b). 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 LCAE category members exhibit a log Koc value of > 5 and are poorly water soluble (< 1 mg/L or even < 0.05 mg/L). The Guidance on information requirements and chemical safety assessment, Chapter R7.b (ECHA, 2012b) 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,2012a)) 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 one can assume that the availability of the LCAE category members in the sediment environment is very low, which reduces the probability of chronic exposure of sediment organisms in general.

Aquatic ecotoxicity data

Available acute data with fish, aquatic invertebrates and algae as well as chronic aquatic toxicity tests aquatic invertebrates and algae showed that no adverse effects occurred in the range of the water solubility of the LCAE category members (< 1 mg/L or even < 0.05 mg/L). Moreover, no toxic effects on activated sludge microorganisms were observed. The results obtained indicate that the LCAE category members are likely to show no toxicity to sediment organisms as well. It is not expected that results from additional studies with sediment organisms will lie out of the overall ecotoxicological profile of the category.

Metabolism/Bioaccumulation

After absorption, the LCAE category members are expected to be enzymatically hydrolyzed by carboxylesterases yielding the corresponding alcohol and fatty acid. QSAR estimations using BCFBAF v3.0 support the expected rapid biotransformation of this substance with BCF/BAF values of 0.89 - 14.07 and 0.90 - 314 L/kg were obtained, respectively. The metabolism of the hydrolysis products is well established and not of concern in terms of bioaccumulation (for further information see chapter 5.3 of the technical dossier). Summarizing, the LCAE category members are expected to be rapidly hydrolyzed to the respective fatty acid and fatty alcohol. Both hydrolysis products are supposed to be satisfactory metabolized in aquatic organisms. Therefore, the potential for bioaccumulation is low.

Conclusion

Due to its readily biodegradable nature, extensive degradation of the LCAE category members 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, the LCAE category members will be bioavailable to sediment organisms mainly via feed and contact with suspended organic particles. After uptake by sediment species, extensive and fast biotransformation of the substance by carboxylesterases into the corresponding fatty acid and alcohol are 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 (all well below 2000). Furthermore, all available aquatic toxicity data show that no effects occur up to the limit of water solubility. Therefore, the LCAE category members are unlikely to pose a risk for sediment organisms and testing is thus omitted.