Tetra-esterification products of C5-(branched and linear), C7, C8 and C10 fatty acids with pentaerythritol

Endpoint summary

Additional information

Justification for grouping of substances and read-across

The polyol esters category comprises of 49 aliphatic esters of polyfunctional alcohols containing two to six reactive hydroxyl groups and one to six fatty acid chains. The category contains mono constituent, multi-constituent and UVCB substances with fatty acid carbon chain lengths ranging from C5 - C28, which are mainly saturated but also mono unsaturated C16 and C18, polyunsaturated C18, branched C5 and C9,branched C14 – C22 building mono-, di-, tri-, and tetra esterswith an alcohol (i.e. polyol).

The available data allows for an accurate hazard and risk assessment of the category and the category concept is applied for the assessment of environmental fate and environmental and human health hazards. Thus, where applicable, environmental and human health effects are predicted from adequate and reliable data for source substance(s) within the group by interpolation to the target substances in the group (read-across approach) applying the group concept in accordance with Annex XI, Item 1.5, of Regulation (EC) No 1907/2006. In particular, for each specific endpoint the source substance(s) structurally closest to the target substance is/are chosen for read-across, with due regard to the requirements of adequacy and reliability of the available data. Structural similarities and similarities in properties and/or activities of the source and target substance are the basis of read-across.

A detailed justification for the grouping of chemicals and read-across is provided in the technical dossier (see IUCLID Sections 5, 6.1 and 13) and within Chapter 7.1 of the CSR.

All poylol esters have a similar profile having the same environmental fate properties; low water solubility, low mobility in soil, ready biodegradability, low persistence and low bioaccumulation potential. Additionally all polyol esters do not show toxicological effects up to the water solubility limit. Nevertheless for an easier overview the category was organized into three groups, which are characterized according to their major alcohol moiety (NPG, TMP or PE).

The following table illustrates the read across approach taken within the PE ester group of the polyol esters category. For practicality reasons, only the ecotoxicological parameters for the terrestric compartment of the relevant substances used as part of a read across approach for the PE esters of the category have been listed in the table below. The complete data matrix of all polyol esters for terrestrial toxicity is however detailed within the category justification attached in IUCLID section 13 of this dossier.

 

CAS	Toxicity to soil macroorganisms except arthropods	Toxicity to terrestrial arthropods	Toxicity to terrestrial plants	Toxicity to soil microorganisms
85116-93-4 (b)	--	--	--	--
85711-45-1 (a)	NOEC (56 d) ≥ 1000 mg/kg dw soil	Waiving based on CSA	Waiving based on CSA	RA: CAS 25151-96-6
25151-96-6	NOEC (56 d) ≥ 1000 mg/kg dw soil	Waiving based on CSA	Waiving based on CSA	EC50 (28 d) > 1000 mg/kg dw soil
67762-53-2	RA: CAS 71010-76-9 RA: CAS 68604-44-4 RA: CAS 25151-96-6	Waiving based on CSA	Waiving based on CSA	RA: CAS 25151-96-6
71010-76-9	NOEC (14 d) ≥ 1000 mg/kg dw	Waiving based on CSA	Waiving based on CSA	RA: CAS 25151-96-6
68441-68-9	--	--	--	--
85586-24-9	RA: CAS 71010-76-9 RA: CAS 68604-44-4 RA: CAS 25151-96-6	Waiving based on CSA	Waiving based on CSA	RA: CAS 25151-96-6
91050-82-7	RA: CAS 68604-44-4 RA: CAS 25151-96-6 RA: CAS 71010-76-9	Waiving based on CSA	Waiving based on CSA	RA: CAS 25151-96-6
19321-40-5	RA: CAS 68604-44-4 RA: CAS 25151-96-6 RA: CAS 71010-76-9	Waiving based on CSA	Waiving based on CSA	RA: CAS 25151-96-6
68604-44-4	NOEC (56 d) ≥ 1000 mg/kg dw soil	Waiving based on CSA	Waiving based on CSA	RA: CAS 25151-96-6
62125-22-8	RA: CAS 68604-44-4 RA: CAS 25151-96-6 RA: CAS 71010-76-9	Waiving based on CSA	Waiving based on CSA	RA: CAS 25151-96-6
68440-09-5	RA: CAS 68604-44-4 RA: CAS 25151-96-6 RA: CAS 71010-76-9	Waiving based on CSA	Waiving based on CSA	RA: CAS 25151-96-6
189200-42-8	--	--	--	--
11138-60-6 (c)	--	--	--	--

a) Category members subject to the REACh Phase-in registration deadline of 31 May 2013 are indicated in bold font

b) Substances that are either already registered under REACh or not subject to the REACh  Phase-in registration deadline of 31 May 2013, are indicated in normal font

c) Substance of the TMP group used as read across substance (aquatic toxicity) for the PE esters group.

Lack of data for a given endpoint is indicated by “--“.

NOTE: Not all of polyol esters within the category are discussed in this endpoint summary i.e. only polyol esters of the PE group relevant for this discussion, in particular PE polyol esters which have terrestrial toxicity data available. For further information on the complete polyol ester category please refer to category justification (IUCLID Section 13).

Testing of the toxicity on earthworm evaluates the exposure to the test substance via soil pore water, surface contact as well as by ingestion of soil particles. A long-term test is considered not be relevant as the results of the chemical safety assessment according to Annex I of Regulation (EC) No 1907/2006 did not indicate the need to investigate further effects of the substance on terrestrial organisms. All category members have been shown to be readily biodegradable and therefore do not have a potential for persistence and thus no indirect chronic exposure of the soil. Additionally, no toxicity was observed in the standard acute toxicity tests to aquatic organisms on the three trophic levels (fish, daphnia, algae). Since indirect exposure is ruled out due to the ready biodegradability of the substance, only direct exposure could pose a risk. A higher solubility would imply that if exposure were to occur this substance would not only be adsorbed to soil particles (log Koc >5) but also concentrations may exist within the soil pore water also. The smaller fatty acid chain length increases the water solubility and therefore the bioavailability in the pore water. Water solubility is negatively correlated with the C-chain length of the fatty alcohol and fatty acid (Lide, 2005). Therefore, a substance with shorter fatty acid chains with higher water solubility can be seen as a worst case for absorption via pore water since it has an increased bioavailability in the pore water (ECHA, 2012). The substances with longer fatty acid chains with higher adsorption potential represent a worst case for the uptake via ingestion of soil bounded particles.

For the assessment of terrestrial toxicity 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. This is supported by further evidence from literature data. This data showed that soil microorganism communities are well capable of degrading fatty acid esters (Hita et al., 1996 and Cecutti et al., 2002) and use them as energy source (Banchio & Gramajo, 1997). Based on the available information, effects on soil microorganisms are not expected to be of concern.

Based on the currently available data it can be concluded that the terrestrial toxicity of the members of the PE esters is low. All substances within the group are characterized by similar physico/chemical parameters like low water solubility (< 0.3 mg/L) and high log Koc (> 3), indicating a similar behaviour in the environment. The log Kow values of the PE esters are also high (> 5). The TMP ester decanoic acid, ester with 2-ethyl-2-(hydroxymethyl)-1,3-propanediol octanoate (CAS 11138-60-6) which is also considered in the PE esters group has an experimentally determined log Kow (> 2.7) supported by calculated values according to KOWWIN programme v1.67 (log Kow = 10.64-13.59). The group members are predominately esters of pentaerythritol with varying fatty acid chain lengths (C5-C28 as well as C16 unsaturated and C18 unsaturated) and thus, a similar metabolic pathway is expected. Consequently, bioaccumulation is not expected due to rapid metabolisation.

Further considerations:

All members of the group are readily biodegradable (> 60% biodegradation in 28 days). The Guidance on information requirements and chemical safety assessment, Chapter R7.b (ECHA, 2012) states that once insoluble chemicals enter a standard STP, they 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. Nevertheless, once this contact takes place, these substances are expected to be removed from the water column to a significant degree by adsorption to sewage sludge (Guidance on information requirements and chemical safety assessment, Chapter R.7a, (ECHA, 2012)) and the rest will be extensively biodegraded (due to ready biodegradability). Thus in conclusion, due to its readily biodegradable nature, extensive degradation of this substance in conventional STPs will take place, thus, discharged concentrations of these substances into the aqueous compartment are likely to be very low. If direct/indirect application of the substances occurs (indirect via sludge application) will occur, the substance will again be rapidly degraded until ultimate biodegradation.

Metabolisms/Bioaccumulation

After absorption, the group members are expected to be enzymatically hydrolyzed by carboxylesterases yielding the corresponding alcohol and fatty acid. The test substances have a log Kow of > 4 indicating a potential for bioaccumulation. But due to the low water solubility, rapid environmental biodegradation and metabolisation via enzymatic hydrolysis, a relevant uptake and bioaccumulation in aquatic organisms is not expected. Enzymatic breakdown will initially lead to the free fatty acid and the free alcohol (e. g. pentaerythritol). From literature it is well known, that these hydrolysis products will be metabolized and excreted in fish effectively (Heymann, 1980; Lech & Bend, 1980; Lech & Melancon, 1980; Murphy & Lutenske, 1990). This is supported by low calculated BCF values of 0.89 – 24.7 L/kg ww (BCFBAF v3.01, Arnot-Gobas, including biotransformation, upper trophic). 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 or Chapter 4.3 Bioaccumulation.

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

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