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Sediment toxicity

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Description of key information

Key value for chemical safety assessment

Additional information

No experimental data evaluating the toxicity to sediment organisms is available for the category PFAE linear. Since all members of the category are readily biodegradable, chronic exposure of sediment organisms is unlikely. In addition, available data indicate, that members of the PFAE linear are not bioaccumulative. Based on the available information, toxicity to sediment organisms is not expected to be of concern.

Intrinsic properties and fate/ exposure

All members of the PFAE linear 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, 2012b). Therefore, after passing through conventional STPs, only low concentrations of these substances are likely to be (if at all) released into the environment.

Aquatic ecotoxicity data

The PFAE linear is a robust category with sufficient experimental data for the aquatic toxicity covering acid carbon numbers from C6 to C10 and total carbon numbers ranging from C10 to C38. Short-term aquatic toxicity data is available for all trophic levels within the PFAE linear category. Long-term data is available for aquatic invertebrates and algae. Based on the experimental data, the majority of category members exhibit no acute and chronic toxicity to aquatic organisms, up to the limit of water solubility. Only two esters with Adipic acid (C6) as dicarboxylic acid component and short chain alcohols, were observed to exhibit ecotoxicological effects (CAS 105-99-7, Dibutyl adipate and CAS 6938-94-9, Diisopropyl adipate).

Metabolisms/Bioaccumulation

After absorption, members of the PFAE linear category are expected to be enzymatically hydrolysed in vivo by the ubiquitary enzyme carboxylesterase, yielding the corresponding alcohols and dicarboxylic acid. QSAR estimations using BCFBAF v3.0 support the expected rapid biotransformation of this substance with BCF/BAF values of < 29 L/kg, respectively (Arnot-Gobas estimation including biotransformation, upper trophic level).

The metabolism of the hydrolysis products: alcohol (e.g. Isopropanol) and dicarboxylic acid (e.g. Adipic acid) is well established and not of concern in terms of bioaccumulation (for further information see chapter 5.3 of the technical dossier).

Conclusion

Due to its readily biodegradable nature, extensive degradation of all members of the PFAE linear category in conventional STPs will take place and only low concentrations are expected to be released (if at all) into the environment. After uptake by sediment species, extensive and fast biotransformation of these substances by carboxylesterases into dicarboxylic acids 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 members of the PFAE linear category will not be bioaccumulative. Therefore, all members of the PFAE linear category are unlikely to pose a risk for sediment organisms in general and testing is thus omitted.

A detailed reference list is provided in the technical dossier (see IUCLID, section 13) and within CSR.

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