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Toxicity to terrestrial plants

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Description of key information

The chemical safety assessment according to Annex I of Regulation (EC) No. 1907/2006 does not indicate the need to investigate further the toxicity to terrestrial plants.

Key value for chemical safety assessment

Additional information

No experimental data on toxicity to terrestrial plants are available for the members of the PE esters group. Generally, all members show high adsorption potential (log Koc 3.3 – 30.23). Exposure of plants to these substances is expected to be very limited, since they are not expected to be found in the pore water in significant quantities, due to poor water solubility and high adsorption potential.

Nevertheless, as read-across for the members of the PE esters group with longer fatty acid chains (i.e. fatty acids, C16-18 (even numbered), esters with pentaerythritol (CAS 85116-93-4) and fatty acids, C8, C10, C12, C14, C16 esters with pentaerythritol, reaction product of coconut oil fatty acids, C8-10 fatty acid mix and pentaerythritol (CAS 85049-33-8)), an early seedling growth toxicity test according to OECD 208 with the TMP ester fatty acids, C16-18 (even numbered) and C16-18-unsatd. (even numbered), triesters with trimethylolpropane (CAS 68002-79-9) is available. In this read-across study the effects on Lycopersicon esculentum, Raphanus sativus and Avena sativa were determined. The study reported no toxicity of the substance to the tested plant species (NOEC 300 mg/kg for L. esculentum and R. sativus respectively, NOEC 1000 mg/kg for A. sativa). Nevertheless this documentation is in-sufficient for an accurate assessment (only short abstract available) as it is not clear if this is related to phytotoxic or any physical effects hence it must be disregarded and the assessment for terrestrial toxicity can be based on the available terrestrial toxicity data for the polyol esters category.

In absence of a clear indication of selective toxicity towards a specific group of organisms, terrestrial toxicity of PE esters was tested on earthworms, Eisenia fetida or Eisenia andrei, as recommended by the “Guidance on information requirements and chemical safety assessment Chapter R.7c: Endpoint specific guidance” (ECHA, 2012).

Five studies (according to OECD 222, 207 and 216) are available for four PE group members. Chronic toxicity studies conducted under GLP according to OECD 222 with earthworms exposed to the group members fatty acids, C16-18 and C18-unsaturated, esters with pentaerythritol (CAS 85711-45-1), 2,2-bis(hydroxymethyl)-1,3-propanediyl dioleate (CAS 25151-96-6) and fatty acids, C16-18 and C18-unsatd., tetraesters with pentaerythritol (CAS 68604-44-4) resulted in no effects on mortality and reproduction up to a concentration of 1000 mg/kg dw soil in all three chronic toxicity studies. Additionally, in an acute test according to OECD 207 with decanoic acid, mixed esters with heptanoic acid, octanoic acid, pentaerythritol and valeric acid (CAS No. 71010-76-9) no mortality occurred in both the control and treatment group resulting in a NOEC (14 d) ≥ 1000 mg/kg dw soil. These four substances represent both ends of the group and the results are used to cover other polyol esters by interpolation. The category member decanoic acid, mixed esters with heptanoic acid, octanoic acid, pentaerythritol and valeric acid (CAS 71010-76-9) belongs to the lower end of the category (C5-C10 fatty acid chain length) and is assumed to represent worst case in terms of absorption via pore water as explained above. The long-term studies with fatty acids, C16-18 and C18-unsaturated, esters with pentaerythritol (CAS 85711-45-1), 2,2-bis(hydroxymethyl)-1,3-propanediyl dioleate (CAS 25151-96-6) and fatty acids, C16-18 and C18-unsatd., tetraesters with pentaerythritol (CAS 68604-44-4) strengthen the read-across approach for esters with fatty alcohol chain lengths of C16-18 and C18 unsaturated. The toxicity to soil micro-organisms with 2,2-bis(hydroxymethyl)-1,3-propanediyl dioleate (CAS 25151-96-6) was tested in a GLP study according to OECD 216. The EC50 for the nitrogen transformation was calculated to be > 1000 mg/kg dw soil (the highest concentration tested). Available data for toxicity to aquatic microorganisms for the PE ester group members confirms the determination of a lack of toxicity to soil microorganisms. No inhibition of respiration rate of aquatic microorganisms was observed in any of the available studies for the PE esters group members.

Based on the above mentioned available data, the terrestrial toxicity of the members of the PE esters group is expected to be very low. Additionally, the members are not expected to remain in the terrestrial environment, due to ready biodegradation. A relevant uptake and bioaccumulation in aquatic organisms is not expected due to the low water solubility, rapid environmental biodegradation and metabolisation via enzymatic hydrolysis. Enzymatic breakdown will initially lead to the free fatty acid and the free alcohol (e. g. pentaerythritol). This is supported by a low calculated BCF value of 0.89 – 24.7 L/kg ww (BCFBAF v3.01, Arnot-Gobas, including biotransformation, upper trophic) of the members of the PE esters group. Since the hydrolysis products are supposed to be satisfactory metabolized in organisms, no potential for bioaccumulation is to be expected. For more information on the metabolism of enzymatic hydrolysis products please refer to IUCLID section 5.3, 6.3 or Chapter 4.3 Bioaccumulation.

In conclusion, the PE esters group members are unlikely to pose a risk for terrestrial plants based on a) the lack of exposure and b) the low toxicity as expected for this substance for the terrestrial compartment based on the available experimental data, metabolism considerations and the lack of adverse effects in aquatic ecotoxicity tests.

In accordance with Regulation (EC) No. 1907/2006, Annex X, Column 2, 9.4 further studies on the effects on terrestrial organisms do not have to be conducted since the chemical safety assessment indicates that toxicity to terrestrial plants is not expected to be of concern.