Glycerol tristearate

Short-term toxicity to fish

Description of key information

No effects up to the limit of water solubility (WS < 1 mg/L)

Additional information

No experimental data evaluating the acute toxicity of glycerol tristearate (CAS No. 555-43-1) to aquatic invertebrates are available. Therefore, toxicity data from structurally related analogue substances, propane-1,2,3-triyl trisheptanoate (CAS No. 620-67-7) and castor oil hydrogenated (CAS No. 8001-78-3) are used as read-across in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5. All three substances are esters formed from the combination between fatty acids and glycerol.

Propane-1,2,3-triyl trisheptanoate and glycerol tristearate are triglycerides (the three hydroxyl functional groups of the glycerol molecule are esterified with fatty acids), differing only in the length of the C-chain of their fatty acid components (C7 and C18respectively). Castor oil hydrogenated is predominantly a C18 hydroxylated triglyceride, therefore sharing the same C-chain length with glycerol tristearate. The behaviour of these three substances in the water phase is expected to be very similar based on low water solubility values (< 1 mg/L) and high log Pow (>8). Nevertheless, the bioavailability of glycerol tristearate and castor oil hydrogenated to aquatic organisms is expected to be lower than that of propane-1,2,3-triyl trisheptanoate due to their high molecular weight (> 700 g/Mol) which can hinder the crossing of biological membranes (Guidance on information requirements and chemical safety assessment, Chapter R.11 (ECHA, 2008)). Based on this information, reading-across from castor oil hydrogenated and

propane-1,2,3-triyl trisheptanoate is justified and, in the case of propane-1,2,3-triyl trisheptanoate, can be considered as a worst-case approach for glycerol tristearate.

One study evaluating the acute toxicity of propane-1,2,3-triyl trisheptanoate (CAS No. 620-67-7) to fish is available (Scholz, 1994). This test was conducted according to EU Method C1, under GLP conditions. Fish (Danio rerio) were exposed to the test substance for 96 hours within a semi-static water regime at 20 ± 2 °C. After 96 hours exposure, no mortality was observed in either treatment or control groups. Therefore, the LC50 (96 h) was determined to be > 95 mg/L (nominal concentration) and > 64 mg/L (measured concentration). The determination of measured test concentrations was performed by DOC (Dissolved Organic Carbon) analysis, which is more suitable for substances with higher water solubility. The high reported measured concentration (64 mg/L) despite the low water solubility of the substance (< 0.05 mg/L) shows that probably other constituents from the solution have been accounted for as test substance. Nevertheless, since no effects were observed it can be stated that no acute toxicity to fish within the range of the water solubility of propane-1,2,3-triyl trisheptanoate is expected.

 

Additionally, a study was conducted with castor oil hydrogenated (CAS No. 8001-78-3) according to ISO 7346-1. Fish (Danio rerio) were exposed for 96 hours to the test substance also within a semi-static water regime. No mortality was observed at any of the tested concentrations and therefore the LC50 (96 h) was > 10,000 mg/L (nominal concentration).

 

Based on the results obatined for structurally related analogue substances (in accordance with Regulation (EC) No. 1907/2006), Annex XI, 1.5), glycerol tristearate is not expected to show acute toxicity to fish up tothe limit of its water solubility (<1 mg/L).