Fatty acids, C8-10, mixed esters with adipic acid and trimethylolpropane

Sediment toxicity

Description of key information

Taking all available information into account the PFAE mixed and branched 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 PFAE mixed and branched 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 information indicates, that the PFAE mixed and branched 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 PFAE mixed and branched 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, 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 PFAE mixed and branched category members exhibit a log Koc value of >5 and are 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 (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, one can assume that the availability of the PFAE mixed and branched 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 toxicity tests for three trophic levels (fish, invertebrates, algae) and long-term studies available for algae showed no adverse effects occurred in the range of the water solubility of the substance (< 1 mg/L) for the members of the PFAE mixed and branched category. The obtained results indicate that the PFAE mixed and branched category members are also not likely to show toxicity to sediment organisms. Some studies for the PFAE mixed and branched category members are still ongoing. The dossier will be updated as soon as possible and the Chemical Safety Assessment according to Annex I of Regulation (EC) No 1907/2006 will be re-evaluated based on the outcome of the additional studies. Nevertheless, it is not expected that the results from the additional studies will lie out of the overall ecotoxicological profile of the category.

Metabolism/Bioaccumulation

Bioaccumulation is not expected for the members of the PFAE mixed and branched category. Based on the molecular weight (512-1969 g/mol), size and structural complexity of the substances the uptake from medium into sediment organisms is considered to be low (e.g.Dimitrov et al., 2002). The supporting BCF/BAF values estimated with the BCFBAF v3.01 program, Arnot-Gobas model including biotransformation (BCF and BAF values of 0.89-0.91 L/kg and 0.89-10.92 L/kg, respectively), also indicate that this substance will not be bioaccumulative (all well below 2000).

Conclusion

Due to their readily biodegradable nature, extensive degradation of these substances in conventional STPs will take place and only low concentrations are expected to be released (if at all) into the environment. Absorption of the PFAE mixed and branched category members is not expected due to the molecular weight (512-1969 g/mol), size and structural complexity of the molecules. Therefore, the potential for bioaccumulation is low. Furthermore, aquatic toxicity data show that no effects occur up to the limit of water solubility. Therefore, the PFAE mixed and branched category members are unlikely to pose a risk for sediment organisms in general and testing is thus omitted.