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Description of key information

The chemical safety assessment according to Annex I of Regulation (EC) No. 1907/2006 does not indicate the need to investigate further the toxicity to sediment organisms.

Key value for chemical safety assessment

Additional information

The chemical safety assessment according to Annex I of Regulation (EC) No. 1907/2006 does not indicate the need to investigate further the effects on sediment organisms. The target substance fatty acids, vegetable-oil, esters with dipropylene glycol (CAS 95009-41-9) is readily biodegradable, 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 the test substance is not bioaccumulative. Based on the available information, toxicity to sediment organisms is not expected to be of concern.

Distribution to the environmental compartments intrinsic properties and fate

Since direct release of the substance to the aquatic system is not anticipated, release to the aquatic compartment might occur via sewage treatment plants only. According to the Guidance on information requirements and chemical safety assessment, Chapter R7.b (ECHA, 2012) 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.7b, ECHA, 2012). The substance of concern is characterized by a log Koc value of > 3 (MCI method) and is poorly water soluble (<0.01 mg/L at 20 °C, pH=5.82 - 5.92) and thus will undergo the same fate as stated in the Guidance document. Furthermore, the substance was determined to be readily biodegradable and 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, release of the substance into the aqueous/sediment compartment is likely to be negligible.

Aquatic ecotoxicity data

Acute aquatic toxicity tests showed no adverse effects occurred in the range of the water solubility of the substance (<0.01 mg/L at 20 °C, pH=5.82 - 5.92). The obtained results indicate that the substance is likely to show no toxicity to sediment organisms as well.

Metabolisms/Bioaccumulation

After absorption, the substance is expected to be enzymatically hydrolyzed by carboxylesterases yielding the corresponding alcohol and fatty acid. Ethylene distearate has a log Kow > 10 (KOWWIN v1.68) indicating a potential for bioaccumulation. But due to the low water solubility, rapid environmental biodegradation and metabolisation via enzymatic hydrolysis, a relevant uptake and bioaccumulation in aquatic organisms is not expected. Enzymatic breakdown will initially lead to the free fatty acid and the free glycol alcohol (e.g. propylene glycol). From literature it is well known, that these hydrolysis products will be metabolized and excreted in fish effectively (Heymann, 1980; Lech & Bend, 1980; Lech & Melancon, 1980; Murphy & Lutenske, 1990). This is supported by low calculated BCF values of 2.065 - 19.26 L/kg ww (BCFBAF v3.01, Arnot-Gobas, including biotransformation, upper trophic). Please refer to IUCLID Section 5.3 for a detailed overview on bioaccumulation. Thus, taking all information into account, the bioaccumulation of the substance is assumed to be low.

Conclusion

Only low concentrations are expected to be released (if at all) into the environment due to its readily biodegradable nature. Extensive degradation will take place in conventional STPs. Once present in the aquatic compartment, further biodegradation will occur and, due to the high log Kow, low water solubility and high adsorption potential, sediment organisms might be exposed to the substance mainly via feed and contact with suspended organic particles. After uptake by sediment species, extensive and fast biotransformation of the substance by carboxylesterases into the free fatty acid 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 this substance will not be bioaccumulative (all well below 2000). Furthermore, aquatic toxicity data show that no effects occur up to the limit of water solubility. Therefore, the substance is unlikely to pose a risk for sediment organisms in general and testing is thus omitted, hence toxicity to sediment organisms is not expected to be of concern and thus there is no need to investigate further the effects on sediment organisms.

In conclusion, due to a) the observed absence of toxicological effects on aquatic organisms, b) the lack of chronic exposure and c) the, acknowledged metabolism of fatty acid esters, toxic effects on sediment dwelling invertebrates can be excluded.