Sorbitan monolaurate, ethoxylated

Endpoint summary

Additional information

Justification for grouping of substances and read-across

There are no data available for the Terrestrial toxicity of Sorbitan monolaurate, ethoxylated (CAS 9005-64-5). In order to fulfil the standard information requirements set out in Annex X, X.X, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006, read-across from structurally related 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 physico-chemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity.

The ecotoxicological parameters for terrestrial toxicity are presented in the table below.

Table 2. Ecotoxicological parameters for terrestrial toxicity

CAS No.	Soil macroorganisms	Terrestrial arthropods	Terrestrial plants	Soil microorganisms
Target substance
9005-64-5	RA: CAS 91844-53-0 RA: CAS 26266-58-0	Waiving	Waiving	WoE
Source substances
91844-53-0	LC50 (14d) > 1000 mg/L	Waiving	Waiving	WoE
26266-58-0	LC50 (14d) > 1000 mg/L	Waiving	Waiving	WoE

 

Terrestrial toxicity

In absence of a clear indication of selective toxicity towards a specific group of organisms, terrestrial toxicity of Sorbitan esters was tested on the earthworm Eisenia fetida, as recommended by the “Guidance on information requirements and chemical safety assessment Chapter R.7c: Endpoint specific guidance” (ECHA, 2012). No studies are available for terrestrial arthropods, terrestrial plants or soil microorganisms. However, since Sorbitan esters are mainly poorly soluble in water and have potential to adsorb to solid soil particles, a soil dwelling organisms, 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 of these substances.

Studies according to the OECD Guideline 207 were conducted with the read-across substances Sorbitan, octanoate (2:3) (CAS No. 91844-53-0) and Anhydro-D-glucitol trioleate (CAS No. 26266-58-0), and no mortality occurred during the 14 day exposure period with none of the two substances. Sorbitan, octanoate (2:3) is smaller than the target substance and represents a worst case in terms of bioavailability from pore water. Anhydro-D-glucitol trioleate is larger and has a higher adsorption potential based on Koc and a higher log Kow. It thus represents a worst case for uptake via soil particle bound substance. Since no effects were observed for any of the two substances, there is no reason to expect effects for Sorbitan monolaurate, ethoxylated, and the data gap can be covered by interpolation.

The earthworm studies indicate that the toxicity of Sorbitan monolaurate, ethoxylated to terrestrial organisms is low. Moreover, the substance is 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; Suldano et al, 1992; Barron et al., 1999, Wheelock et al., 2008). Therefore, it is expected that under physiological conditions, Sorbitan monolaurate, ethoxylated 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 (Croda 1951, Mattson and Nolen 1972, Treon 1967, Wick and Joseph 1953). The resulting fatty acids are either metabolised via the β-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), and is thus naturally present in the terrestrial environment. The ethoxylation is not expected to significantly increase the toxicity of D-glucitol. Using the OECD toolbox Vs. 2.3, the liver metabolism simulator provided 42 potential metabolites indicating that the ethoxylated part of the substance remains intact. Studies on genotoxicity (Ames test, chromosomal aberration and gene mutation in mammalian cells) were negative, indicating no reactivity of the test substance or its metabolites under the test conditions. Additionally, Sorbitan monolaurate, ethoxylated is readily biodegradable and is thus expected to be rapidly removed from the terrestrial environment by soil microorganisms.

Furthermore, the aquatic studies indicate no hazard. In the acute studies with Sorbitan monolaurate, ethoxylated, an EC50 values above 10 mg/L were obtained. Such aquatic data can be used as an indicator for potential effects on soil organisms (ECHA, 2012), and in the case of Sorbitan monolaurate, ethoxylated effects are not to be expected. Furthermore, the chronic study with Daphnia magna, available for Sorbitan monolaurate, ethoxylated, resulted in a NOEC > 1 mg/L.

Moreover, no effects were observed in the long-term study with Daphnia magna up to a loading rate of 10 mg/L. Acute aquatic EL50 values were > 10 mg/L or above the water solubility limit of the substance.

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.

References:

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