Tetradecyl stearate

Endpoint summary

Additional information

There are no data available on the toxicity of tetradecyl stearate (CAS 17661-50-6) to terrestrial organisms. In order to fulfil the standard information requirements set out in Annex IX, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006, read-across from two structurally related source substances was conducted.

In accordance with Article 13 (1) of Regulation (EC) No 1907/2006, "information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met.” In particular for human toxicity, information shall be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from structurally related substances (grouping or read-across).

Having regard to the general rules for grouping of substances and read-across approach laid down in Annex XI, Item 1.5, of Regulation (EC) No 1907/2006 whereby substances may be predicted as similar provided that their physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity. The source substances 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) and Fatty acids, C8-10, C12-18-alkyl esters (CAS 95912-86-0) are representative to evaluate the terrestrial toxicity of tetradecyl stearate to earthworms. 2-octyldodecyl isooctadecanoate is characterized by a C18iso fatty acid (isooctanoate) and a C20iso alcohol (2-octyldodecanol). This substance covers the upper end of C-chain distribution of the target substance. The second source substance is characterized by a C8-C10 fatty acid and a C12-C14 alcohol covering the lower end of C-chain distribution of the target substance. Using both substances for the prediction of terrestrial toxicity of the target substance is reliable since the endpoint is covered by interpolation. A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

Exposure of the soil compartment is generally considered to be low. Even if exposed to the soil the target substance is readily biodegradable indicating that it will not be persistent in the environment. Indirect exposure via irrigation or atmospheric transport is considered to be negligible based on the physico-chemical properties of the target substance (water solubility:0.5-1 µg/L at 20 °C, pH 6; vapour pressure: < 0.0001 Pa).

Experimental data investigating the toxicity of the target substance to earthworms are available from the representative source substances 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) and Fatty acids, C8-10, C12-18-alkyl esters (CAS 95912-86-0). Testing of the toxicity on earthworm evaluates the exposure to the test substance via soil pore water, surface contact as well as by ingestion of soil particles. Due to the high adsorption potential (log Koc > 5), long-term testing was considered to be relevant to investigate the effects of the substance on terrestrial organisms. Both available studies were performed according to OECD 222. The study with the source substance 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) resulted in a NOEC (56 d) of ≥ 1000 mg/kg soil dw whereas the study with the source substance Fatty acids, C8-10, C12-18-alkyl esters (CAS 95912-86-0) resulted in low toxicity with a NOEC (56 d) of 500 mg/kg soil dw.

After absorption, the target substance is expected to be enzymatically hydrolyzed by carboxylesterases yielding to the corresponding alcohol and fatty acid. QSAR estimations using BCFBAF v3.01 support the expected rapid biotransformation of this substance.When including biotransformation, BCF and BAF values of 0.89 - 0.90 and 2.67 - 8.08 L/kg, respectively, were obtained indicating biotransformation (Arnot-Gobas estimate, including biotransformation, upper trophic).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, the target substance is expected to be rapidly hydrolyzed to the respective fatty acid and fatty alcohol. Both hydrolysis products are supposed to be satisfactorily metabolized in terrestrial organisms. Therefore, the potential for bioaccumulation is low. Available acute and chronic aquatic toxicity tests to fish, invertebrates, algae and microorganisms showed no adverse effects occurred in the range of the water solubility (0.5-1 µg/L at 20 °C, pH 6). These results support the assumption that the target substance is of low toxicity to terrestrial organisms.

The available data for toxicity to activated sludge microorganisms support the determination of a lack of toxicity to soil microorganisms. No inhibition of respiration rate of activated sludge microorganisms was observed in the available experimental study. The Guidance Document (ECHA, 2014, page 136) states that a test on soil microbial activity will only be additionally necessary for a valid PNEC derivation if inhibition of sewage sludge microbial activity has occurred and this is clearly not the case. This is supported by further evidence from literature data. These data show that soil microorganism communities are well capable of degrading fatty acid esters (Hita et al., 1996 and Cecutti et al., 2002) and use them as energy source (Banchio & Gramajo, 1997). Based on the available information, effects on soil microorganisms are not expected to be of concern, and consequently, no further testing is required.

In conclusion the target substance is of low toxicity to terrestrial organisms based on all available data.