Dehydrated sorbitol, C18 (unsaturated) fatty acid esters, ethoxylated

Short-term toxicity to fish

Description of key information

No effects up to the water solubility limit.

Additional information

Since no experimental studies investigating the short-term toxicity of sorbitan monooleate, ethoxylated (1-6.5 moles ethoxylated) (CAS 9005-65-6) to fish are available, in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5 a read-across to the structurally related substance sorbitan monolaurate, ethoxylated (degree of ethoxylation: 1 - 6.5; CAS 9005-64-5) was conducted. Both substances are considered to be similar based on their chemical structure. The target substance is characterized as a monoester of sorbitan and a C18 unsatd. fatty acid (degree of ethoxylation: 3 and 5) whereas the source substance consists of sorbitan monoesterified with C12 and C14 fatty acids (degree of ethoxylation: 1 - 6.5). The smaller fatty acid chain length of the source substance should increase the water solubility and therefore the bioavailability in the water phase. The water solubility is negatively correlated with the C-chain length of the fatty acid (Lide, 2005). Therefore, it is possible to extrapolate from a source substance with a higher water solubility since it has an increased bioavailability in the water phase (ECHA, 2012). Sorbitan monooleate, ethoxylated (1-6.5 moles ethoxylated) is expected to be poorly soluble in water Two studies according to OECD 105 (flask method) (Frischmann, 2014a & 2014b) resulted in a water solubility of > 500 g/L (at 20 °C, pH 8.29 - 9.39). However, the water solubility was estimated by visual inspection only with the result of increasing viscosity of solution while adding test substance to the water. Due to the fact, that the formation of the gel is a continuous process, no discrete point could be identified at which dissolution in water switches to gelling. For poorly soluble surface active substances a CMC measurement can help to define a limit value for water solubility taking into account the concentration of substance in solution, when micelles begin to form. The CMC of two batches of the test substance was difficult to achieve as the samples were poorly water soluble (Humphrey, 2014). Therefore, only approximate CMC curves and values could be obtained (approx. 100 mg/L (literature value 33.7 mg/L). The lower water solubility value and the difficulties during measurement of the CMC give clear evidence that the substance is poorly water soluble. This is supported by the structurally similar substance sorbitan monolaurate, ethoxylated (1 - 6.5 EO) (CAS 9005-64-5) which has a water solubility value of < 0.2 mg/L (20 °C, pH = 6.3 - 7.9, EU method A.6). Finally a water solubility value of approx. 100 mg/L is taken for assessment. This read-across is justified in detail in the overall summary (IUCLID section 6.1) and within the analogue justification in IUCLID Section 13. In this case of read-across, the best suited (highest degree of structural similarity, nearest physico-chemical properties) read-across substance was used for the assessment.

The available study with the source substance sorbitan monolaurate, ethoxylated (degree of ethoxylation: 1 - 6.5) was conducted according to OECD 203 (GLP) with the zebrafish Danio rerio (Teigeler, 2012). A limit test with a nominal Water Accommodated Fraction (WAF) of 100 mg/L was tested. No mortality was recorded after 96 h resulting in a LL50 (96 h) of > 100 mg/L.

Based on the available result from one structurally related read-across substance (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) which is characterized by a similar ecotoxicological profile and comparable structure, it can be concluded that sorbitan monooleate, ethoxylated (1-6.5 moles ethoxylated) (CAS 9005-65-6) will not exhibit short-term effects to fish up to the limit of water solubility.