Sorbitan C16-18 (even numbered) fatty acid esters, ethoxylated (1-6.5 moles ethoxylated)

Endpoint summary

Additional information

Experimental studies on the biodegradability ofsorbitan C16-18 (even numbered) fatty acid esters, ethoxylated (1-6.5 moles ethoxylated)are not available. In order to fulfil the standard information requirements set out in Annex VII, 8.5, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006, read-across from the structurally related source substances sorbitan monolaurate ethoxylated (CAS 9005-64-5) and sorbitan stearate (CAS 1338-41-6) 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 its chemical structure, the target substance belongs to the family of ethoxylated sorbitan fatty acid esters, also called polysorbates. Polysorbates are produced by partial esterification of sorbitan with a fatty acid followed by polymerization with ethylene oxide. Polysorbates differ in the number of ethoxy groups and the number and types of fatty acid moieties (EPA, 2005). The first source substance sorbitan monolaurate, ethoxylated (CAS 9005-64-5) with a shorter chain (C12 fatty acid) analogue belongs to this family and is considered as a suitable structural analogue based on the presence of common functional groups. The further source substance sorbitan monostearate (CAS 1338-41-6), belongs to the family “sorbitan fatty acid esters”, which are generally produced via esterification of sorbitan with a fatty acidto give the respective mono-, di-, tri- and n-esters as products of esterification (JECFA, 1973; Gennaro, 1990; Canterbery, 1997).They are non-ethoxylated analogues of respective ethoxylated substances involved, i.e. stearates.

The target substance sorbitan C16-18 (even numbered) fatty acid esters, ethoxylated (1-6.5 moles ethoxylated) is characterised by a low vapour pressure (<0.0001 Pa at 20 °C, SPARC v4.6), a water solubility of 148 mg/L (at 20 °C, pH = 7.02-7.3, OECD 105) and a log Koc indicating a potential for adsorption to soil and sediment particles (log Koc 2.5 - 17.3, based on MCI, KOCWIN v2.00). Based on the experimental result from two biodegradation studies conducted with the above listed source substances (according to OECD 301 C and F) the target substance is considered to be readily biodegradable (62.5% to 88% after 28 d, based on read across). Thus, it is assumed that sorbitan C16-18 (even numbered) fatty acid esters, ethoxylated (1-6.5 moles ethoxylated) will be significantly degraded in sewage treatment plants. In the case insoluble chemicals enter a standard Sewage Treatment Plant (STP), it 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, accordingto the guidance on information requirements and chemical safety assessment, Chapter R.7b (ECHA, 2016). As a result of the potential for adsorption of the substance (log Koc2.5 - 17.3, MCI method, KOCWIN v2.00) a removal from the water column to a significant degree by adsorption to sewage sludge can be expected (guidance on information requirements and chemical safety assessment, Chapter R.7b, ECHA, 2016). In conclusion, the concentration ofthe substance in conventional STP effluents is presumably marginal. Due to ready biodegradability and based on the chemical structure, abiotic degradation via hydrolysis is considered as not relevant for the substance. Moreover, the substance is not volatile (VP < 0.0001 Pa at 20 °C) and thus evaporation to the air and subsequent transport through the atmosphere to other environmental compartments is not likely.

Bioaccumulation is not expected for sorbitan C16-18 (even numbered) fatty acid esters, ethoxylated (1-6.5 moles ethoxylated), based on low BCF values of 0.89 to 12.5 L/kg (ww) calculated for the main substance components (BCFBAF v3.01, Arnot-Gobas, including biotransformation, upper trophic). Moreover, the high molecular weight and high log Kow values further enhance the assumption of low bioaccumulation potential of the target substance. In addition, the substance is expected to be metabolised in aquatic organisms by enzymatic hydrolysis and further common metabolic pathways of the hydrolysed products.

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

References:

Canterbery, R.C. (1997). Chemical structure of Sorbitan fatty acid esters. Correspondance date 11-17-97, 2 pages, available for review: Director, Cosmetic Ingredient Review, 1101 17th Street, NW, Suite 310, Washington, DC 20036, USA.

US EPA (2005). ACTION MEMORANDUM. Reassessment of six inert ingredient exemptions from the requirement of a tolerance. United States Environmental Protection Agency, Washington, D.C. 20460

Gennaro, A.R., ed. (1990). Remington´s pharmaceutical sciences, 18th ed. 1308, Easton, PA: Mack Publishing.

JECFA Sorbitan monostearate monograph (1973): http://www.fao.org/ag/agn/jecfa-additives/specs/Monograph1/Additive-434.pdf