Tetra-esterification products of C5 -(linear and branched) , C7, C8, C9, C10 fatty acids with pentaerythritol

Sediment toxicity

Description of key information

Toxic effects on sediment dwelling invertebrates can be excluded.

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. All polyol esters are ready 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 polyol esters 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). Our substances of concern is characterized by a log Koc value of > 5 (MCI method) and is poorly water soluble (< 1 mg) and thus will undergo the same fate as stated in the Guidance document. Furthermore, all polyol esters are 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, exposure, of these polyol esters into the aqueous/sediment compartment are 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 (< 1 mg/L). The obtained results indicate that all polyol esters are likely to show no toxicity to sediment organisms as well.

Metabolisms/Bioaccumulation

The polyol esters have log Kow > 5 (KOWWIN v1.67) 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. After absorption, polyol esters are expected to be enzymatically hydrolyzed by carboxylesterases yielding free fatty acid and the free alcohol (e. g. pentaerythritol). 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 0.89 – 6.32 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 of the polyol esters category. Thus, taking all information into account, the bioaccumulation of this category member is assumed to be low.

Conclusion

Due to its readily biodegradable nature, extensive degradation of this 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, sediment organisms might be exposed to polyol esters 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, all polyol esters are 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 metabolisation of fatty acid esters, toxic effects on sediment dwelling invertebrates can be excluded.