Propane-1,2,3-triyl 2-ethylhexanoate

Endpoint summary

Additional information

In accordance with Annex IX, column 2 (9.4) of Regulation (EC) No. 1907/2006, testing for toxicity to soil macroorganisms is not required since direct and indirect exposure of the soil compartment is unlikely. Furthermore, Propane-1,2,3-triyl 2-ethylhexanoate is unlikely to pose a risk for terrestrial organisms considering the low toxicity as expected for this substance. Therefore, no tests on terrestrial organisms are provided.

Intrinsic properties and fate/ exposure

Propane-1,2,3-triyl 2-ethylhexanoate (CAS No. 7360-38-5) is readily biodegradable (85% O2 consumption in 28 days; METI, 2002). 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, 2017b). Therefore, after passing through conventional STPs, only low concentrations of these substances are likely to be (if at all) released into the environment.

Furthermore, the substance exhibits a log Koc value of 6.28 and is poorly water soluble (< 0.05 mg/L measured in aqua dest).The Guidance on information requirements and chemical safety assessment, Chapter R.7b (ECHA, 2017b) 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 compartment are likely to be very low. If direct/indirect application of the substances occurs (indirect via sludge application) will occur, the substance will again be rapidly degraded until ultimate biodegradation. In addition, use information on this substance as presented in chapter 3.5 of technical dossier, exclude direct exposure to soil. In accordance with Annex IX, column 2 (9.4) of Regulation (EC) No. 1907/2006, testing for toxicity to soil macroorganisms is not required since direct and indirect exposure of the soil compartment is unlikely. Therefore, no tests on terrestrial organisms are provided.

Further considerations:

Aquatic ecotoxicity data

Acute and chronic aquatic toxicity tests of the substance Propane-1,2,3-triyl 2-ethylhexanoate (CAS No. 7360-38-5) and the read across analogue Propane-1,2,3-triyl trisheptanoate (CAS No. 620-67-7) to fish, invertebrates, algae and microorganisms showed no adverse effects occurred in the range of the water solubility of the substance (< 0.05 mg/L measured in aqua dest). The obtained results indicate that Propane-1,2,3-triyl 2-ethylhexanoate is likely to show no toxicity to soil organisms as well. The Guidance on information requirements and chemical safety assessment, Chapter R.7c (ECHA, 2017c, p.121) states: “it will normally not be possible to derive a robust PNEC for the purposes of a soil screening assessment from acute aquatic toxicity testing showing no effect. The absence of chronic or long-term effects in aquatic organisms up to the substance solubility limit, or of acute effects within the solubility range above 10 mg/L can be used as part of a Weight of Evidence argument to modify/waive the data requirements of Annex IX and X.” Based on the available information, toxicity to terrestrial soil macroorganisms is not expected to be of concern.

Metabolisms/Bioaccumulation

After absorption, Propane-1,2,3-triyl 2-ethylhexanoate is expected to be enzymatically hydrolysed in vivo by the ubiquitary enzyme carboxylesterase, yielding the corresponding alcohol and 2-ethylhexanoic acid. QSAR estimations using BCFBAF v3.0 support the expected rapid biotransformation of this substance with BCF/BAF values of 1.05 L/kg, respectively (Arnot-Gobas estimation including biotransformation, upper trophic level).

The metabolism of the hydrolysis products: alcohol (i.e. Glycerol) and 2-ethylhexanoic acid is well established and not of concern in terms of bioaccumulation (for further information see chapter 5.3 of the technical dossier). This is also underlined by their low log Kow values (-1.65 and 2.96, for glycerol and 2-ethylhexanoic acid, respectively; values calculated using KOWWIN v1.68).

Summarizing, Propane-1,2,3-triyl 2-ethylhexanoate is expected to be rapidly hydrolyzed to 2-ethylhexanoic acid and Glycerol. Both hydrolysis products are supposed to be satisfactory metabolized in organisms and are not bioaccumulative. Therefore, no potential for bioaccumulation is to be expected.

Conclusion

Propane-1,2,3-triyl 2-ethylhexanoate is unlikely to pose a risk for terrestrial organisms based on a) the lack of exposure and b) the low toxicity as expected for this substance for terrestrial organisms based on metabolism considerations and the lack of adverse effects in aquatic ecotoxicity tests. Therefore, no tests on terrestrial organisms are provided.

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