Fatty acids, C16, C18 and C18-unsaturated, C12-15 alcohol (linear and branched), esters

Sediment toxicity

Link to relevant study record(s)

Reference

Endpoint:

sediment toxicity: long-term

Data waiving:

other justification

Justification for data waiving:

other:

Description of key information

Based on all the available information, toxicity to sediment organisms is not expected to be of concern.

Additional information

No experimental data evaluating the toxicity of the target substance Fatty acids, C16, C18 and C18-unsaturated, C12-15 alcohol (linear and branched), esters to sediment organisms are available. However, only negligible discharge to the aquatic environment is expected to occur via sewage treatment plants (STPs) due to: a) the ready biodegradability and b) the high adsorption properties of the substance, resulting in an effective removal in sewage treatment plants. Whatever fraction should still reach the water compartment is expected to undergo rapid and ultimate degradation and the remainder will adsorb to organic soil and sediment particles where sediment organisms are potentially exposed via feed and contact with suspended organic particles. However, based on the physico-chemical properties, the bioavailability of the substance is expected to be low due to its strong binding behavior. Therefore, chronic exposure of sediment organisms is unlikely. Furthermore, the substance is not toxic to aquatic organisms up to the limit of water solubility.

Based on all the available information, toxicity to sediment organisms is therefore not expected to be of concern.

Intrinsic properties and fate

Fatty acids, C16, C18 and C18-unsaturated, C12-15 alcohol (linear and branched), esters is readily biodegradable. According to the Guidance on information requirements and chemical safety assessment, Chapter R.7b (ECHA, 2017), readily biodegradable substances can be expected to undergo rapid and ultimate degradation in most environments, including biological STPs. Therefore, only low concentrations of this substance are expected to be released into the environment, if at all.

Furthermore, Fatty acids, C16, C18 and C18-unsaturated, C12-15 alcohol (linear and branched), esters has an estimated log Koc of > 5.0 and is poorly soluble in water (< 6.57 µg/L at 20 °C, pH 6.3, OECD 105). The Guidance on information requirements and chemical safety assessment, Chapter R.7b (ECHA, 2017) 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. Thus, discharge into the aqueous/sediment compartment is likely to be negligible and chronic exposure of sediment organisms is improbable.

Aquatic ecotoxicity

According to the available short-term toxicity data for fish and aquatic algae, as well as long-term toxicity data for aquatic invertebrates and algae, Fatty acids, C16, C18 and C18-unsaturated, C12-15 alcohol (linear and branched), esters is not expected to cause acute or chronic toxicity to aquatic organisms up to the limit of water solubility (< 6.57 µg/L, at 20 °C, pH 6.3). Moreover, due to the low water solubility, it is highly unlikely that relevant, bioavailable concentrations of the test item will ever occur in the water phase, i.e. that concentrations high enough to induce any measurable acute or chronic effects in aquatic organisms are highly unlikely to be attained.

Furthermore, no toxic effects on activated sludge microorganisms were observed. Significant deviations from this overall ecotoxicologcial profile are not expected and it is thus concluded that Fatty acids, C16, C18 and C18-unsaturated, C12-15 alcohol (linear and branched), esters is unlikely to cause toxic effects to sediment organisms.

Metabolism/Bioaccumulation

If absorption by aquatic organisms should occur, Fatty acids, C16, C18 and C18-unsaturated, C12-15 alcohol (linear and branched), esters is expected to be enzymatically hydrolyzed by carboxylesterased into the corresponding free fatty acid and alcohol components. The metabolism 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 target 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), 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 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 water. Therefore, it is concluded that Fatty acids, C16, C18 and C18-unsaturated, C12-15 alcohol (linear and branched), esters does not pose a risk to sediment organisms.