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Sediment toxicity

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Description of key information

The results of the chemical safety assessment do not indicate the need to investigate further the toxicity to sediment organisms

Key value for chemical safety assessment

Additional information

No experimental data evaluating the toxicity to sediment organisms is available for Fatty acids, C12-16 (even numbered) and C18-unsatd., methyl esters (CAS No. 1234694-02-0). Since the substance is readily biodegradable, 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 test substance is not bioaccumulative. Based on the available information, toxicity to sediment organisms is not expected to be of concern.

Intrinsic properties and fate

All substances included in the SCAE Me category 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 2008). Therefore, after passing through conventional STPs, only low concentrations of these substances are likely to be (if at all) released into the environment. Once present in the aquatic compartment further degradation will occur.

Aquatic ecotoxicity data

Aquatic short-term and long-term toxicity tests of the substance to fish, invertebrates, algae showed no adverse effects in the range of the water solubility of the substance. In addition, no chronic toxicity of SCAE Me on Eisenia fetida was observed. The obtained results indicate that Fatty acids, C12-16 (even numbered) and C18-unsatd., methyl esters is likely to show no toxicity to sediment organisms as well.

Metabolisms/Bioaccumulation

Bioaccumulation in in aquatic (including sediment) organisms is not expected for Fatty acids, C12-16 (even numbered) and C18-unsatd., methyl esters. After uptake by fish species, extensive and fast biotransformation of the SCAE Me(s) by carboxylesterases into fatty acids and methanol is expected. Fatty acids will be further used by these organisms as their main source of energy throughout all the different life stages (early development, growth, reproduction, etc.). Rapid metabolism of analogue ester compounds (involving hydrolysis into fatty acids and methanol) in fish has been observed in vitro, with half-lives in fish liver homogenates below 6 minutes. In vivo fish tests reported BCF values ranging from 1 to 70 for similar ester substances, supporting the argument that rapid metabolism takes place even when log Kow values are above the trigger value of 3. The supporting BCF/BAF values estimated with the BCFBAF v3.01 program also indicate that these substances will not be bioaccumulative (all well below 2000).

Conclusion

Due to its readily biodegradable nature, extensive degradation of the substance in conventional STPs will take place and only low concentrations are expected to be released (if at all) into the environment. Bioaccumulation is not expected due to low exposure and fast metabolism after oral or dermal uptake. Furthermore, aquatic toxicity data show that no effects occur up to the limit of water solubility. Therefore, Fatty acids, C12-16 (even numbered) and C18-unsatd., methyl esters is unlikely to pose a risk for sediment organisms in general and testing is thus omitted.