2-ethyl-2-[[(1-oxoheptyl)oxy]methyl]propane-1,3-diyl bisheptanoate

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. Therefore although the polyol esters category does not need to be grouped with respect to their environmental effects, in order to achieve 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 TMP ester group of the polyol esters category. For practicality reasons, only the ecotoxicological parameters for the terrestrial compartment of the relevant substances used as part of a read across approach for the TMP esters of the category have been listed in the table below. A complete data matrix of all polyol esters for terrestrial toxicity is mapped in detailed in the category justification attached in IUCLID section 13 of this dossier.

 

Ecotoxicological parameters for the terrestrial toxicity of the TMP ester group

 

CAS	Toxicity to soil macroorganisms except arthropods	Toxicity to terrestrial arthropods	Toxicity to terrestrial plants	Toxicity to soil microorganisms
78-16-0 (a)	NOEC ≥ 1000 mg/kg	Waiving	Waiving	Waiving
189120-64-7 (b)	--	--	--	--
11138-60-6	--	--	--	--
91050-89-4	RA: CAS 78-16-0	Waiving	Waiving	Waiving
68002-79-9	--	--	NOEC = 300 - 1000 mg/kg	--
68002-78-8	RA: CAS 68541-50-4	Waiving	Waiving	Waiving
57675-44-2	--	--	--	--
68541-50-4	NOEC ≥ 1000 mg/kg	Waiving	Waiving	Waiving

a)      Category members subjected 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

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 TMP group with terrestrial toxicity data. For further information on the complete polyol ester category please refer to category justification (IUCLID Section 13).

Experimental data on the toxicity of TMP esters to terrestrial organisms are available for 2-ethyl-2-[[(1-oxoheptyl)oxy]methyl]propane-1,3-diyl bisheptanoate (CAS 78-16-0) and Fatty acids, C14-18 and C16-18 unsatd., triesters with trimethylolpropane (CAS-No. 68002-79-9). 

The long-term toxicity of 2-ethyl-2-[[(1-oxoheptyl)oxy]methyl]propane-1,3-diyl bisheptanoate (CAS 78-16-0) and 2-ethyl-2-(((1-oxoisooctadecyl)oxy)methyl)-1,3-propanediyl bis (isooctadecanoate) (CAS 68541-50-4) to earthworms was tested in two studies according to OECD guideline 222. The studies focused on the effect of the test substances on earthworm survival, growth and reproduction (Eisner, 2013a,b). Mortality or detrimental effects on earthworm growth were not observed and thus a NOEC 1000 mg/kg soil based on mortality was reported. The reproduction rate was determined after another 28 days by counting the number of hatched juveniles. A significant difference to the control was not observed and thus a NOEC ≥ 1000 mg/kg was determined

The short-term toxicity of Fatty acids, C14-18 and C16-18 unsatd. triesters with trimethylolpropane (CAS-No. 68002-79-9) was tested according to OECD 208. The study determined no toxicity of the TMP ester on the early seedling growth of the tested plant species (NOEC = 300 mg/kg for Lycopersicon esculentum and Raphanus sativus respectively, NOEC= 1000 mg/kg for Avena sativa).

Generally the available data on the members of the TMP ester group indicate a low bioavailability and a low toxicity of the substances to terrestrial organisms. Studies on the short-term and chronic toxicity of the TMP ester group to aquatic organism determined no toxicity up to the limit of water solubility. The substances are all readily biodegradable and thus are expected to be largely eliminated in sewage treatment plants by degradation. Furthermore based on the low water solubility (<1 mg/L) of the TMP ester group members and the high log Koc (6.31 – 14.91) the substances are expected to be mechanically removed inthe primary settling tank and fat trap and thus, only limited amounts will get in contact with activated sludge organisms. Consequently a significant release to the environment of the TMP esters via STP effluents is not expected. However, when the substances are released to the environment a rapid degradation is assumed. Since a respiration inhibition of aquatic microorganisms was not observed in the available studies on TMP esters a comparable result is expected for soil microorganisms. This assumption is supported by several studies investigating the degradation of fatty acid esters by soil microorganisms(Hita et al., 1996, Banchio & Gramajo, 1997 and Cecutti et al., 2002). The characteristics of the TMP ester group (i.e. low water solubility, low vapour pressure and high log Koc) determine the environmental fate of the substances. A distribution to the soil compartment is most probable. The substances have a potential to adsorb to soil particles and thus might be ingested by soil dwelling organisms. However, acute toxicity of the TMP ester group members to terrestrial organisms is not expected based on the data available for short-term aquatic toxicity. When ingested the substances are expected to be rapidly metabolised and excreted. Bioaccumulation is not anticipated. This also supported by the low BCF/BAF values (0.89 – 3.16 L/kg;Arnot-Gobas) calculated for the TMP ester group members. An uptake of the TMP esters by plant roots is not likely due to the low water solubility and high adsorption potential of the substances.

Further considerations:

All TMP polyol esters are readily biodegradable (> 60% biodegradation in 28 days). According to the Guidance on information requirements and chemical safety assessment, Chapter R.7b, readily biodegradable substances can be expected to undergo rapid and ultimate degradation in most environments, including biological Sewage Treatment Plants (STPs) (ECHA, 2012). Therefore, the substance will be effectively removed by conventional STPs and, if any, only small quantities will be discharged to the aquatic environment. Thus the environmental concentration of the substance is assumed to be very low. Furthermore, if the substance enters the environment via direct or indirect application a rapid degradation of the substance will take place.

 

Metabolisms/Bioaccumulation

After uptake, TMP polyol esters are expected to be enzymatically hydrolyzed by carboxylesterases to 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 metabolism via enzymatic hydrolysis, a relevant uptake and bioaccumulation in aquatic organisms is not expected. Enzymatic breakdown will initially lead to the fatty acid and the alcohol. From literature it is well known, that these hydrolysis products will be effectively metabolised and excreted by fish (Heymann, 1980; Lech & Bend, 1980; Lech & Melancon, 1980; Murphy & Lutenske, 1990). This is supported by low calculated BCF values of 0.89 – 3.16 L/kg ww (BCFBAF v3.01, Arnot-Gobas, including biotransformation, upper trophic). Please refer to IUCLID Section 5.3 for a detailed overview on bioaccumulation of the TMP esters group members.

Thus the TMP polyol esters are not expected 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 according to the available experimental data, metabolism considerations and the lack of adverse effects in aquatic ecotoxicity tests.