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Long-term toxicity to aquatic invertebrates

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Description of key information

NOELR (21 d) = 10 mg/L (nominal, WAF)

Key value for chemical safety assessment

Additional information

Since no studies investigating the long-term toxicity to aquatic invertebrates of sorbitan C16-18 (even numbered) fatty acid esters, ethoxylated (1-6.5 moles ethoxylated) are available, in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5 read across was conducted to the structurally related source substances sorbitan stearate (CAS 1338-41-6) and sorbitan monolaurate ethoxylated (CAS 9005-64-5).

The available study tested the long-term toxicity of sorbitan stearate (CAS 1338-41-6) to aquatic invertebrates. The study was performed according to OECD guideline 211 and GLP (MoE, 2006). The test organism Daphnia magna was exposed to nominal concentrations of 5, 16, 50, 160 and 500 mg/L under semi-static conditions for 21 d. The test concentrations 5 and 16 mg/L were prepared using tetrahydrofuran as pre-solvent. Before test initiation, the solvent was removed and the solution was filtered. The higher concentrations were prepared without solvent as water accommodated fractions (WAF). Since a solvent was used, the lower concentrations are not actual loading rates and these test concentrationscannot be evaluated as WAF. No inhibition of reproduction was observed during the test, in fact, the number of juveniles produced at 5 and 16 mg/L was higher than in the control. At the three higher concentrations, 100% mortality of the parental Daphnia occurred, and reproduction could not be evaluated. The reported measured values for the three highest concentrations (4.65, 11.9, 17.1 mg/L) were significantly above the water solubility of the substance. Therefore, it can be assumed that undissolved test material was present and probably caused the mortality observed at the higher concentrations. Due to the methodological deficiencies in this test, the reported NOELR and -LC50 need to be taken with caution. Nevertheless, at nominal concentration of 16 mg/L the test solution was reported to be clear and colourless during the test period, and no adverse effects occurred. NOELR was determined to be 16 mg/L.

The study conducted with the source substance sorbitan monolaurate, ethoxylated (CAS 9005-64-5) was performed according to OECD guideline 211 and GLP (Schlechtriem, 2012). The test organism Daphnia magna was exposed to the test substance under semi-static conditions, at nominal loading rates of 1.0, 3.2, 10.0, 32.0 and 100 mg/L for 21 d. The test solutions were prepared as water accommodated fractions (WAF). At 32 mg/L, a significant effect on reproduction was observed. Also the body length of parent animals was affected by the treatment at this concentration, and 60% parental mortality occurred. At 100 mg/L, 100% mortality of the parent animals was observed. Therefore, reproduction could not be evaluated for this concentration. The NOELR (21 d) for reproduction was thus determined to be 10 mg/L.

Based on these results from the structurally related read-across substance (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5), it can be assumed that thesorbitan C16-18 (even numbered) fatty acid esters, ethoxylated (1-6.5 moles ethoxylated)will exhibit similar long term effects to aquatic invertebrates.