Hexanoic acid, 2-ethyl-, C16-18-alkyl esters

Endpoint summary

Additional information

There are no data available for the chronic toxicity towards aquatic invertebrates of Hexanoic acid, 2-ethyl, C16-18 alkyl esters (CAS No. 90411-68-0). In order to fulfil the standard information requirements set out in Annex IX, 9.1, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006, read-across from structurally related substances was conducted.

In accordance with Article 13 (1) of Regulation (EC) No 1907/2006, "information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met.” In particular, information shall be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from structurally related substances (grouping or read-across).

Having regard to the general rules for grouping of substances and read-across approach laid down in Annex XI, 1.5, of Regulation (EC) No 1907/2006, whereby substances may be predicted as similar provided that their physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity.

Aquatic Toxicity

CAS	90411-68-0	135800-37-2	26399-02-0
Chemical name	Hexanoic acid, 2-ethyl, C16-18 alkyl esters	Fatty acids, C8-16, 2-ethylhexyl esters	2-Ethylhexyl oleate
MW	368.6-396.7 g/mol	256.4-396.7 g/mol	394.7 g/mol
Short term toxicity to fish	LL50 > 100 mg/L	LC50 > 10000 mg/L	-
Long term toxicity to fish	Waiving based on CSA	-	-
Short term toxicity to aquatic invertebrates	EL50 > 100 mg/L	EC50 > 100 mg/L	EC50 > 100 mg/L
Long term toxicity to aquatic invertebrates	RA: CAS 135800-37-2 RA: CAS 26399-02-0	NOEC >= 1 mg/L	NOEC >= 1 mg/L
Toxicity to aquatic algae	ErL50/ ErL10 > 110 mg/L	ErC50 > 100 mg/L	ErC50 > 100 mg/L
Toxicity to microorganisms	EC50 > 1000 mg/L	-	-

The above mentioned substances are considered to be similar on the basis of the structural similar properties and/or activities. The available endpoint information for chronic aquatic invertebrates of C8-16-Fatty acid-2-ethylhexyl ester (CAS No. 135800-37-2) and 2-Ethylhexyloleat (CAS No. 26399-02-0) is used to predict the same endpoint for Hexanoic acid, 2-ethyl, C16-18 alkyl esters (CAS No. 90411-68-0).

A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

Discussion

Acute toxicity of Hexanoic acid, 2-ethyl-, C16-18 alkyl esters (CAS No. 90411-68-0) to aquatic organisms was assessed for three trophic levels (algae, invertebrates and fish). Only for acute aquatic toxicity data are available for this substance. Therefore in accordance with Article 13 (1) of Regulation (EC) No 1907/2006, a read across to C8-16-Fatty acid-2-ethylhexyl ester (CAS No. 135800-37-2) and 2-Ethylhexyloleat (CAS No. 26399-02-0) was applied in order to cover the long term toxicity to aquatic invertebrates.

A read across from C8-16-Fatty acid-2-ethylhexyl ester and 2-Ethylhexyloleat to Hexanoic acid, 2-ethyl-, C16-18 alkyl esters to cover the long-term toxicity to aquatic invertebrates endpoint is acceptable as first all substances have common functional groups being fatty acid esters. The fact that the target substance is an ester of 2-ethylhexanoic acid and fatty alcohols with carbon chain lengths of C16 - C18 while the source substances are esters of 2-ethylhexanol and fatty acids with a carbon chain length of C8-C16 and C18, is not considered to invalid the read-across approach. This is assumed due to the similar physico-chemical properties and the common breakdown products of the substances, which are expected to be rapidly metabolised in the body via enzymatic hydrolysis to the starting materials (e.g., see Barron et al. 1999 for metabolism of esters in fish), which then fed into body’s natural catabolic processes, such as ß-oxidation and citric acid cycle (e.g., Rahn et al., 1973; Henderson, 1996). 

All substances are measured or calculated to be insoluble in water and the main components of the substances have similar molecular weights of 368.6 - 396.7 g/mole (CAS No. 90411-68-0), 256.43 – 312.54 g/mole (CAS No. 135800-37-2) and 394.69 g/mole (CAS No. 26399-02-0). The volatility of all substances is low (< 0.01 Pa at 20 °C). Hence, the behaviour, the fate, the bioaccumulation and thus the toxicity of the substances in the aquatic environment are considered to be identical.

In all available short-term toxicity tests, no adverse effects occurred in the range of the water solubility of the substance (< 0.15 mg/L measured in aqua dest). The two chronic reproduction tests to Daphnia magna with C8-16-Fatty acid-2-ethylhexyl ester (CAS No. 135800-37-2) and 2-Ethylhexyloleat (CAS No. 26399-02-0) also did not reveal any adverse effects up to the limit of water solubility. Furthermore, the respiration of activated sludge was not inhibited in a 3 hour respiration inhibition test (EC50 (3h) > 1000 mg/L, nominal)). Therefore disturbances in the biodegradation process of a sewage treatment plant are not anticipated for of Hexanoic acid, 2-ethyl-, C16-18 alkyl esters.

In summary, Hexanoic acid, 2-ethyl-, C16-18 alkyl esters (CAS No. 90411-68-0) shows no adverse effects up the limit of water solubility and can thus be considered as not hazardous to the aquatic environment.

A detailed reference list is provided in the technical dossier (see IUCLID, section 13) and within the CSR.