Dodecyl nonan-1-oate

Sediment toxicity

Description of key information

In consideration of all the available information,it is concluded that lauryl nonanoate (CAS 17671-26-0) is unlikely to pose a risk for sediment organisms. Therefore, further testing was not proposed.

Additional information

No experimental data is available for the toxicity oflauryl nonanoate (CAS 17671-26-0)to sediment organisms is available. However, only negligible release from sewage treatment plants into surface waters is expected due to a): the ready biodegradability and b) the high adsorption properties of the substance, resulting in an effective removal by sewage treatment plants. Furthermore, the substance is not toxic to aquatic organisms up to the limit of water solubility and the potential for bioaccumulation is judged to be low. Therefore, a chronic exposure of sediment organisms is unlikely and toxicity to sediment organisms is not expected to be of concern.

Intrinsic properties and fate

Lauryl nonanoate (CAS 17671-26-0) is 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, 2016). Therefore, only low concentrations of the substance are likely to be released into the environment through conventional STPs, if at all.

Furthermore, the substance has a log Koc > 5.0 and is poorly soluble in water (2.43 µg/L). The Guidance on information requirements and chemical safety assessment, Chapter R.7b (ECHA, 2016) 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 come into 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, 2016) and whatever remains will be extensively biodegraded (due to ready biodegradability). Thus, the amount of the substance discharged into the aqueous/sediment compartment is likely negligible.

In consideration of the available information presented above, it is presumed that the bioavailability of the substance in the sediment compartment is very low, which reduces the probability of chronic exposure of sediment organisms in general.

 

Aquatic ecotoxicity

Available studies on the acute toxicity to fish, aquatic invertebrates and algae as well as chronic toxicity to aquatic invertebrates and algae showed that no adverse effects occurred in the range of the water solubility of lauryl nonanoate (2.43 µg/L). Moreover, no toxic effects on activated sludge microorganisms were observed. Therefore, toxicity to sediment organisms is not expected. It is unlikely that additional studies testing the toxicity to sediment organisms will obtain results that significantly deviate from the overall ecotoxicological profile of the substance.

 

Metabolism/Bioaccumulation

In the case absorption by aquatic organisms should occur, lauryl nonanoate (CAS 17671-26-0) is expected to be enzymatically hydrolyzed by carboxylesterases into the corresponding free fatty acid and alcohol components. The metabolization 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). In consideration of all the available information, it is concluded that the potential for bioaccumulation is low.

 

Conclusion

Due to ready biodegradability and high adsorption, only negligible concentrations of the substance are expected to be discharged into water bodies, if at all. Whatever fraction is released is expected to rapidly degrade or adsorb to particles of sediment and soil where sediment organisms are potentially exposed via feed and contact with suspended organic particles. However, based on the physico-chemical properties of the substance (i.e. strong binding behaviour), its bioavailability is expected to be low. If uptake should occur, extensive and fast biotransformation of the substance and its metabolites is expected by the action of ubiquitous carboxylesterases.

Furthermore, the available aquatic toxicity data suggest that no toxic effects occur up to the limit of water solubility. Moreover, due to the extremely low water solubility of the substance, relevant concentrations of the substance are not expected to ever be attained in the aquatic environment. Therefore, lauryl nonanoate (CAS 17671-26-0) is unlikely to pose a risk to sediment organisms. Therefore, further testing was not proposed.

 

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