Fatty acids, C14-18 and C18-unsatd., branched and linear, 2-ethylhexyl esters

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Read-across category

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

growth rate

 Table1: Results from key studies of source chemical of category for toxicity to aquatic algae and cyanobacteria

Name of the substance	CAS	Fatty acids chain length	Type ofalcohol	MW	Appareance	Toxicity to aquatic algae
Fatty acids, C8-16, 2- ethylhexyl esters	135800-37-2	C8-16	2-ethylhexanol	256.42 – 368.65	Liquid	Experimental result: ErC50(72h) > 100 mg/L (nom., filt.) Scenedesmus subspicatus
Fatty acids, coco, 2-ethylhexyl esters	92044-87-6	C12-14	2-ethylhexanol	312.53 – 340.60	liquid	No data
2-Ethylhexyl palmitate	29806-73-3	C16	2-ethylhexanol	368.65	Liquid	No data
Fatty acids, C16-18 and C18-unsatd., 2-ethylhexyl esters	85049-37-2	C16-18, C18:1	2-ethylhexanol	368.65 – 396.7	Liquid	Experimental result: EL50 )= 281.37 mg/L (WAF) Skeletonema costatum
Fatty acids, C16-18, 2-ethylhexyl esters	91031-48-0	C16-18	2-ethylhexanol	368.65 - 396.7	Liquid	Experimental result: EC50 (96h) = 300 mg/mL (nom.)NOEC (96h.) : 30 mg/L (nom.) Scenedesmus subspicatus
2-Ethylhexyloleate	26399-02-0	C18:1	2-ethylhexanol	394.67	Liquid	Experimental result: ErC50(72h) > 100 mg/L (nom., filt.)Scenedesmus subspicatus
2-Ethylhexylstearate	22047-49-0	C18	2-ethylhexanol	396.7	Liquid	No data

 

Similar ecotoxicity profile

Based on the experimental data, the category members have low toxicity to aquatic algae. Additionally, the exposure concentrations of aquatic organisms are expected to be low due to the very low water solubility of the category members. Due to their very poor water solubility, these substances are difficult for aquatic testing. If undissolved test material is not properly removed from test vessels, it may cause physical effects, such as decreasing algae growth by increased turbidity of test solutions, or algae cells getting trapped into oil film or by particles. These effects do not reflect real toxicity ofthe  substancestowards the organisms. Therefore many tests are performed on filtrated solutions to avoid such mechanical effects. All these tests performed on filtrated solution show a 72h-EC50 (biomass or growth rate) > 100 mg/L (nom., filtrated) and demonstrate low adverse effect to algae.

 

Target substance conclusion

Based on the results obtained on the category members, the 72h-EC50(biomass or growth rate) of the target substance "Isostearate2 -ethyl hexyl" to the freshwater algae was considered to be higher than 100 mg/L (nom., filtrated).

Validity criteria fulfilled:

yes

Conclusions:

Based on the results obtained on the category members, the 72h-EC50(biomass or growth rate) of the target substance "Isostearate 2 -ethyl hexyl" to the freshwater algae was considered to be higher than 100 mg/L (nom., filtrated).
Hence the target substance was not classified for acute toxicity to aquatic algae according to CLP criteria.

Executive summary:

According to the Regulation (EC) NO. 1907/2006, Annex XI, 1.5, A Read-Across Category for "Long Chain Fatty Acid, 2-ethylhexyl esters" was performed in order to provide informations on Isostearate 2-Ethylhexyl .

This category was based on common and shared properties as:

-   common functional group,

-   common precursors and the likelihood of common impurities resulting from common process of manufacturing,

-   chemically structurally similar breakdown products obtained via the same biological processes into the organisms, and

-   constant pattern in the changing of the potency of the properties across the category.

Two key studies, considered as relevant and reliable, were performed on the freshwater algae Scenedesmus subspicatus according to national or European standards with the Fatty acids, C8-16, 2-ethylhexyl esters (CAS 135800-37-2) and the 2-Ethylhexyl oleate (CAS 26399-49-0) respectively. The nominal concentration of 100 mg/L without removal of insoluble particles resulted in an inhibition of the algal biomass and growth rate, whereas no adverse effects were observed on algae after removal of insoluble particles (filtration of the 100 mg/L solution). This inhibition of the algal growth observed only in the presence of undissolved test material can be accounted to physical effects. Therefore a 72h-ErC50 > 100 mg/L (nominal, filtrated) was stated for the Fatty acids, C8-16, 2-ethylhexyl esters and the 2-Ethylhexyl oleate.

Other studies were performed on the marine algae Skeletonema costatum with the Fatty acids, C16-18 and C18-unsatd. 2 -ethylhexyl ester, and on Scenedesmus subspicatus with the Fatty acids, C16-18, 2-ethylhexyl ester. These substances were tested without removal of insoluble particles and some inhibition of the algal growth was observed. However the calculated EC50 were always > 100  mg/L (nominal, unfiltrated) which indicates a low toxicity of these substances even in the presence of insoluble particles.

These key studies on algae covered the 2-Ethylhexyl esters of fatty acids with chain length from C8-16, C16-18 with C18 sat. or C18 unsat.,  and C18 alone unsat. Considering the molecular weight and the chain length of the tested substances of the category, the toxicity of the target substance “Isostearate, 2-Ethylhexyl” to the freshwater algae Scenedesmus subspicatus can be established as : 72h-ErC50 > 100 mg/L (nom., filtrated).

Hence, the target substance was not classified for acute toxicity to aquatic algae according to CLP criteria.

Description of key information

Based on the available studies performed on the member of the category and according to the CLP regulation, the 72h-EC50 (biomass or growth rate) on freshwater algae was defined greater than 100 mg/L (nom., filtrated). Hence the registered substance was not classified for acute toxicity to aquatic algae.

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L

Additional information

Justification and rationale of the category approach for the Isostearate 2-ethyl hexyl :

This category group covers 2-ethyl hexyl esters linked with fatty acid chains (C8 to C18) unsatured and satured. This category includes monoconstituent substances and UVCB substances varying fatty acid chain length. This category was made in order to provide sufficient information for physicochemical, ecotoxicological and toxicological characterization of the Fatty acids, C14-18 and C18-unsatd., branched and linear, 2-ethylhexyl esters (CAS No 85186-76-1)

The category group includes:

- Fatty acids, C8-16, 2-ethylhexyl esters (CAS No 135800-37-2)

- Fatty acids, coco, 2-ethylhexyl esters (CAS No 92044-87-6)

- 2-Ethyl hexyl palmitate (29806-73-3)

- Fatty acids, C16-18 and C18-unsatd., 2-ethylhexyl esters (CAS No 85049-37-2)

- Fatty acids, C16-18, 2-ethylhexyl esters (CAS No 91031-48-0)

- 2-Ethylhexyl oleate (CAS No 26399-02-0)

- 2-Ethyl hexyl stearate (CAS No 22047-49-0)

Target substance for Category Approach : Fatty acids, C14-18 and C18-unsatd., branched and linear, 2-ethylhexyl esters (CAS No 85186-76-1)

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 for human toxicity, environmental fate and ecotoxicity, 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)”. Therefore, the available experimental data were collected and evaluated according to Annex XI requirements.

Summary of available studies on source substances for toxicity to algae

Fatty acids, C8-16, 2-ethylhexyl esters CAS 135800-37-2

Two studies were available on the toxicity to aquatic algae with Fatty acids, C8 -16, 2-ethylhexyl esters. The key study with Scenedesmus subspicatus was performed according to EU-Method C.3 with filtered and unfiltered solution of 100 mg/L (Wierich 1998). The filtered solution showed no significant inhibition of algae biomass or growth rate which means that the water soluble part of the test substance turned out not to be toxic to algae. With a more or less homogenous emulsion of test material high inhibitions of algae biomass and growth rate were observed (75.7% and 42.6% respectively). This inhibition observed only in presence of undissolved test material can be accounted to physical effects. Therefore a 72h-ErC50 > 100 mg/L could be stated (nominal, filtrated) .

A supporting study on the marine algae Skeletonema costatum was tested (Gibson 1999),  according to the method ISO 10253 using a WAF. The resulting 72h-ErL50 was determined as 535.6 mg/L (nominal loading rate, unfiltered).

Fatty acids, C16-18 and C18-unsatd., 2 -ethylhexyl esters CAS 85049 -37 -2

As key study (Hudson 2000) on the marine algae Skeletonema costatum was tested according to the method  ISO 10253 using a WAF methodology with the Fatty acids, C16-18 and C18-unsatd., 2 -ethylhexyl. The resulting 72h- ErL50 was determined as 281.4 mg/L (nominal loading rate, unfiltered).

Fatty acids, C16-C18, 2 -ethylhexyl esters CAS 91031-48-0

The toxicity of the Fatty acids, C16-18, 2-ethylhexyl esters to the freshwater algae Scenedesmus subspicatus was investigated according to the method DIN 38412 (Kläs 1994). Nominal concentrations of 30, 100 and 300 mg/L without removal of insoluble particles were tested. No dose-effect relationship was observed for the growth rate, whereas for the biomass, a 96h-EbL50 of 300 mg/L and a 96h-NOEC of 30 mg/L was established. It is assumed that the undissolved particles inhibited the algal growth due to physical effects and not to systemic toxicity.

2-ethylhexyl oleate CAS 26399-02-0

The effects of 2-ethylhexyl oleate to the freshwater algae Scenedesmus subspicatus were investigated (Rieche 1995). This Key study was performed according to the EU-method C.3 considering the VCI concept draft for the acute testing of poorly soluble substances. The test  with a nominal concentration of 100 mg/L without removal of insoluble particles resulted in a mean inhibition of the algal growth rate and biomass of 38.3% and 75.1%, respectively. No effects were observed after removal of insoluble particles (filtration of the test solution) on algal growth rate, and for the biomass a stimulation of 23.1 % was stated. So it can be assumed that undissolved particles inhibited the algal growth due to their physical effects. Therefore a 72h-ErC50 > 100 mg/L can be stated implying that no adverse effect is observed up to the limit of the water solubility.

Conclusion on the target substance

According to the Regulation (EC) NO. 1907/2006, Annex XI, 1.5, A Read-Across Category for "Long Chain Fatty Acid, 2-ethylhexyl esters" was performed in order to provide informations on Isostearate 2-Ethylhexyl .

This category was based on common and shared properties as:

-   common functional group,

-   common precursors and the likelihood of common impurities resulting from common process of manufacturing,

-   chemically structurally similar breakdown products obtained via the same biological processes into the organisms, and

-   constant pattern in the changing of the potency of the properties across the category.

Two key studies, considered as relevant and reliable, were performed on the freshwater algae Scenedesmus subspicatus according to national or European standards with the Fatty acids, C8-16, 2-ethylhexyl esters (CAS 135800-37-2) and the 2-Ethylhexyl oleate (CAS 26399-49-0) respectively. The nominal concentration of 100 mg/L without removal of insoluble particles resulted in an inhibition of the algal biomass and growth rate, whereas no adverse effects were observed on algae after removal of insoluble particles (filtration of the 100 mg/L solution). This inhibition of the algal growth observed only in the presence of undissolved test material can be accounted to physical effects. Therefore a 72h-ErC50 > 100 mg/L (nominal, filtrated) was stated for the Fatty acids, C8-16, 2-ethylhexyl esters and the 2-Ethylhexyl oleate.

Other studies were performed on the marine algae Skeletonema costatum with the Fatty acids, C16-18 and C18-unsatd. 2 -ethylhexyl ester, and on Scenedesmus subspicatus with the Fatty acids, C16-18, 2-ethylhexyl ester. These substances were tested without removal of insoluble particles and some inhibition of the algal growth was observed. However the calculated EC50 were always > 100  mg/L (nominal, unfiltrated) which indicates a low toxicity of these substances even in the presence of insoluble particles.

The key studies on algae covered the 2-Ethylhexyl esters of fatty acids with chain length from C8-16, C16-18 with C18 satd. or C18 unsatd.,  and C18 alone unsatd. Considering the molecular weight and the chain length of the tested substances of the category, the toxicity of the target substance “Isostearate, 2-Ethylhexyl” to freshwater algae Scenedesmus subspicatus can be established as : 72h-ErC50 > 100 mg/L (nom., filtrated).

Hence, the target substance was not classified for acute toxicity to aquatic algae according to CLP criteria.