Fatty acids, rape-oil, mixed esters with 1,4:3,6-dianhydro-d-glucitol, sorbitan and sorbitol

Endpoint summary

Additional information

There are no data available on the toxicity of Fatty acids, rape-oil, mixed esters with 1,4:3,6-dianhydro-d-glucitol, sorbitan and sorbitol (CAS 93334-10-2) to terrestrial organsisms. 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 one structurally related substance 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.

Based on the specification the target substance Fatty acids, rape-oil, mixed esters with 1,4:3,6-dianhydro-d-glucitol, sorbitan and sorbitol is characterized by the alcohol components sorbitol, sorbitan and 1,4:3,6-dianhydro-d-glucitol esterified as mono (mainly), -di- or tri-ester with mainly fatty acids of C18 and C18 unsaturated. The source substance, selected to cover biodegradation is specified as followed:

-         Anhydro-D-glucitol trioleate (CAS 26266-58-0) is characterized as a mono-, di- and tri-ester of sorbitol with mainly C18 unsaturated fatty acids.

A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

In absence of a clear indication of selective toxicity towards a specific group of organisms, terrestrial toxicity was tested on the earthworm Eisenia fetida for the source substance anhydro-D-glucitol trioleate (CAS 26266-58-0), as recommended by the “Guidance on information requirements and chemical safety assessment Chapter R.7c: Endpoint specific guidance” (ECHA, 2012c). No studies are available for terrestrial arthropods, terrestrial plants or soil microorganisms. However, since the substance is poorly soluble (832 µg/L ± 208 µg/L at 20 °C, pH=6.3) in water and has potential to adsorb to solid soil particles, a soil dwelling organism, such as the earthworm, which is exposed to the complete soil system via both dermal and oral uptake, is the most relevant test organism to evaluate the terrestrial toxicity.

The study was conducted according to OECD 207 (GLP) with the source substance anhydro-D-glucitol trioleate (CAS 26266-58-0; Harris, 2012). No mortality occurred during the 14 d exposure period up to a nominal concentration of 1000 mg/kg soil dw. A LC50 (14 d) of > 1000 mg/kg soil dw was derived. The earthworm study shows that the toxicity of the source substance to terrestrial organisms is very low. Moreover, sorbitan esters are expected to be metabolised by organisms after ingestion, which is probably the main uptake route. Esters are known to hydrolyse into carboxylic acids and alcohols by esterases (Fukami and Yokoi, 2012). Carboxylesterase activity has been noted in a wide variety of tissues in invertebrates as well as in fish (Leinweber, 1987; Soldano et al, 1992; Barron et al., 1999, Wheelock et al., 2008). Therefore, it is expected that under physiological conditions, Sorbitan esters will hydrolyse to D-glucitol and the respective fatty acids. The hydrolysis of sorbitan fatty acid esters occurs within a maximum of 48h for mono-, di- and tri-ester but decreases with the number of esterified fatty acid so that no hydrolysis of hexa-ester occurs (Croda, 1951; Mattson and Nolen, 1972; Treon, 1967; Wick and Joseph, 1953). The resulting fatty acids are either metabolised via theβ-oxidation pathway in order to generate energy for the cell or reconstituted into glyceride esters and stored in the fat depots in the body (Berg, 2002). The first step of D-glucitol metabolism involves oxidation by L-iditol dehydrogenase to fructose, which is metabolised by the fructose metabolic pathway (Senti, 1986). D-glucitol is naturally found in several berries and fruits as well as in seaweed and algae (FDA, 1972). Larger sorbitan fatty acid esters that will not be hydrolysed, such as hexaesters, are unlikely to cross biological membranes due to their high molecular weight. Additionally, both, the source and the target substance are readily biodegradable and are thus expected to be rapidly removed from the terrestrial environment by soil microorganisms.

Furthermore, chronic data for Daphnia magna are available from the source substances sorbitan stearate (CAS 1338-41-6) and Sorbitan, (Z)-9-octadecenoate (2:3) (CAS 8007-43-0), and no effects occurred up to the limit of water solubility. Aquatic data can be used as an indicator for potential effects on soil organisms (ECHA, 2012), and in the case of the target substance Fatty acids, rape-oil, mixed esters with 1,4:3,6-dianhydro-d-glucitol, sorbitan and sorbitol (CAS 93334-10-2) effects are not to be expected.

Based on the available information, i.e. very low toxicity to earthworm and to aquatic organisms, rapid metabolism and ready biodegradation, short- and long-term effects on terrestrial organisms are very unlikely. Consequently, no further testing is proposed.

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