Fatty acids, C18-unsatd., trimers, 2-ethylhexyl esters

Sediment toxicity

Description of key information

Taking all available information into account Fatty acids, C18 unsaturated, trimers, 2-ethylhexyl esters is unlikely to pose a risk for sediment organisms and testing is thus omitted.

Additional information

No experimental data evaluating the toxicity to sediment organisms is available for Fatty acids, C18 unsaturated, trimers, 2-ethylhexyl esters (CAS No. 173832-46-7).

Intrinsic properties and fate

Fatty acids, C18 unsaturated, trimers, 2-ethylhexyl esters exhibits a log Koc value of > 5 and is poorly water soluble (< 1 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). Thus, discharged concentrations of this substance (if at all) into the aqueous/sediment compartment are likely to be low.

Considering this, one can assume that the availability of Fatty acids, C18 unsaturated, trimers, 2-ethylhexyl esters in the sediment environment is generally low, which reduces the probability of chronic exposure of sediment organisms in general.

Bioaccumulation

Bioaccumulation is not expected based on the molecular weight (973.62 - 11184 g/mol), size and structural complexity of the substance. The uptake from medium into sediment organisms is considered to be low (Dimitrov et al. (2002)).

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 (BCF and BAF values were calculated to be 0.89 L/kg,).

Aquatic ecotoxicity data

Aquatic toxicity tests conducted with fish, invertebrates and microorganisms showed no toxic effects in the range of the water solubility (< 1 mg/L). The obtained results indicate that Fatty acids, C18 unsaturated, trimers, 2-ethylhexyl esters is likely to show no or only low toxicity to sediment organisms as well.

Conclusion

Due to its log Koc value of > 5, significant adsorption of this substance to activated sludge 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, due to the high log Kow, low water solubility and high adsorption potential, Fatty acids, C18 unsaturated, trimers, 2-ethylhexyl esters will be bioavailable to sediment organisms mainly via feed and contact with suspended organic particles. However, based on the molecular weight, size and structural complexity of the substance the uptake from medium into sediment organisms is considered to be low. This is supported by a calculated BCF value below 2000 L/kg. Furthermore, aquatic toxicity data show that no effects occur up to the limit of water solubility. Fatty acids, C18 unsaturated, trimers, 2-ethylhexyl esters is unlikely to pose a risk for sediment organisms in general and testing is thus omitted.

References

Dimitrov SD, Dimitrova NC, Walker JD, Veith GD, Mekenyan OG. 2002. Predicting bioconcentration factors of highly hydrophobic chemicals. Effects of molecular size. Pure Appl Chem 74 (10): 1823-1830

European Chemicals Agency (ECHA, 2012). Guidance on information requirements and chemical safety assessment, Chapter R.7a: Endpoint specific guidance

 European Chemicals Agency (ECHA, 2012). Guidance on information requirements and chemical safety assessment, Chapter R.7b: Endpoint specific guidance