Nonanoic acid, mixed esters with heptanoic acid, pentaerythritol and valeric acid

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

The assessment of the sediment toxicity should be based on the outcome of aquatic toxicity testing. Pursuant to ECHA decision on a compliance check CCH-D-2114588821-38-01/F a new long-term fish toxicity study with the registered substance will be conducted in the future. The finalised study will be reported in an updated dossier and the hazard assessment will be re-evaluated accordingly. Thus, the strategy of sediment toxicity will be evaluated later when the long-term fish toxicity is available.

Additional information

The assessment of the sediment toxicity should be based on the outcome of aquatic toxicity testing. Pursuant to ECHA decision on a compliance check CCH-D-2114588821-38-01/F a new long-term fish toxicity study with the registered substance will be conducted in the future. The finalised study will be reported in an updated dossier and the hazard assessment will be re-evaluated accordingly. Thus, the strategy of sediment toxicity will be evaluated later when the long-term fish toxicity is available.

 

Taking all available information into account, Monopentaerythritol tetraesters and dipentaerythritol hexaesters of valeric, heptanoic and nonanoic acids is unlikely to pose a risk for sediment organisms and testing is thus omitted.

No experimental data evaluating the toxicity to sediment organisms are available for Monopentaerythritol tetraesters and dipentaerythritol hexaesters of valeric, heptanoic and nonanoic acids. 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 data indicate, that Monopentaerythritol tetraesters and dipentaerythritol hexaesters of valeric, heptanoic and nonanoic acids is not bioaccumulative. Based on the available information, toxicity to sediment organisms is not expected to be of concern.

Intrinsic properties and fate

Monopentaerythritol tetraesters and dipentaerythritol hexaesters of valeric, heptanoic and nonanoic acids 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, 2017). Therefore, after passing through conventional STPs, only low concentrations of the substance is likely to be (if at all) released into the environment.

Furthermore, the substance exhibits a log Koc value of > 5 and has a low water solubility (< 2.01 mg/L at 20°C, pH = 6.5). 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. 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, 2017a)) 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 Monopentaerythritol tetraesters and dipentaerythritol hexaesters of valeric, heptanoic and nonanoic acids in the sediment environment is very low, which reduces the probability of chronic exposure of sediment organisms in general.

Aquatic ecotoxicity data

Available acute data with fish, aquatic invertebrates and algae as well as chronic aquatic toxicity tests aquatic invertebrates and algae showed that no adverse effects occurred in the range of the water solubility (< 2.01 mg/L at 20 °C, pH = 6.5). Moreover, no toxic effects on activated sludge microorganisms were observed. The results obtained indicate that the substance is likely to show no toxicity to sediment organisms as well. It is not expected that results from additional studies with sediment organisms will lie out of the overall ecotoxicological profile of the substance.

Bioaccumulation

After absorption, Monopentaerythritol tetraesters and dipentaerythritol hexaesters of valeric, heptanoic and nonanoic acids is expected to be enzymatically hydrolysed by carboxylesterases yielding the corresponding alcohol and fatty acid. QSAR estimations using BCFBAF v3.1 support the expected biotransformation of this substance with BCF/BAF values of 0.8931 - 0.8947 (Arnot-Gobas estimate, including biotransformation, upper trophic), respectively. 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). Summarizing, Monopentaerythritol tetraesters and dipentaerythritol hexaesters of valeric, heptanoic and nonanoic acids is expected to be hydrolysed to the respective fatty acid and fatty alcohol. Both hydrolysis products are supposed to be satisfactory metabolized in aquatic organisms. Moreover, pentaerythritol has a log Kow < 3 and is not expected to be bioaccumulative. Therefore, the potential for bioaccumulation is low.

Conclusion

Due to its readily biodegradable nature, extensive degradation of the substance 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, further biodegradation will occur and, due to the high log Kow, low water solubility and high adsorption potential, the substance will be bioavailable to sediment organisms mainly via feed and contact with suspended organic particles. After uptake by sediment species biotransformation of the substance by carboxylesterases into the corresponding fatty acid and alcohol are expected. 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 (all well below 2000). Furthermore, all available aquatic toxicity data show that no effects occur up to the limit of water solubility. Therefore, Monopentaerythritol tetraesters and dipentaerythritol hexaesters of valeric, heptanoic and nonanoic acids is unlikely to pose a risk for sediment organisms and testing is thus omitted.