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Ecotoxicological information

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Additional information

The Short Chain Alcohol Esters (SCAE C2-C8) category covers esters from a fatty acid (C8-C29) and a C2-C8 alcohol (ethanol, isopropanol, butanol, isobutanol, pentanol, iso-pentanol, hexanol, 2-ethylhexanol or octanol). This category includes both well-defined mono-constituent substances as well as related UVCB substances with varying fatty acid chain lengths.
Fatty acid esters are generally produced by chemical reaction of an alcohol (e.g. isopropanol) with an organic acid (e.g. stearic acid) in the presence of an acid catalyst (Radzi et al., 2005). The esterification reaction is started by a transfer of a proton from the acid catalyst to the alcohol to form an alkyloxonium ion. Acid is protonated on its carbonyl oxygen followed by a nucleophilic addition of a molecule of the alcohol to a carbonyl carbon of acid. An intermediate product is formed. This intermediate product loses a water molecule and proton to give an ester (Liu et al, 2006; Lilja et al., 2005; Gubicza et al., 2000; Zhao, 2000). Esters are the final product of esterification.
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).
The rationale for grouping the substances in the SCAE C2-C8 category is based on similarities in physicochemical, ecotoxicological and toxicological properties.
In this particular case, the similarity of the SCAE C2-C8 category members is justified, in accordance with the specifications listed in Regulation (EC) No. 1907/2006 Annex XI, 1.5

Grouping of substances and read across, based on representative molecular structure, physico-chemical properties, tox-, ecotoxicological profiles, supported by a robust set of experimental data and QSAR calculations. There is no convincing evidence that any one of these chemicals might lie out of the overall profile of this category, respectively.
 

Grouping of substances into this category is based on:
• Similar/overlapping structural features or functional groups: All category members are monoesters of alcohols (C2-C8) and fatty acids (C8-C29), with 13 to 32 carbons in total.

• Common precursors and the likelihood of common breakdown products via biological

processes: All category members are subject to enzymatic hydrolysis by pancreatic lipases (Mattson and Volpenhein, 1972; and references therein). The resulting free fatty acids and alcohols are absorbed from the intestine into the blood stream. Fatty acids are either metabolised via the beta-oxidation pathway in order to generate energy for the cell or reconstituted into glyceride esters and stored in the fat depots in the body. The alcohols are metabolised primarily in the liver through a series of oxidative steps, finally yielding carbon dioxide (Berg et al., 2002).

• Similar physico-chemical properties: The log Kow and log Koc values of all category members are high (log Kow > 4, log Koc > 3), increasing with the size of the molecule. The substances are poorly soluble in water and have low vapour pressure. 

• Common properties for environmental fate & eco-toxicology: Based on experimental data, all substances are readily biodegradable, with the exception of Fatty acids, C16-18 and C18 unsatd. branched and linear, butyl esters (CAS No. 163961-32 -8), which is inherently biodegradable, and do not show toxic effects up to the limit of water solubility.

• Common levels and mode of human health related effects: All available experimental data indicate that the members of the SCAE C2-C18 category are not acutely toxic, are not irritating to the skin or to the eyes and do not have sensitizing properties. Repeated dose toxicity was shown to be low for all substances. None of the substances showed mutagenic effects, and toxicity to reproduction was low throughout the category.
 

Having regard to the general rules for grouping of substances and read-across approach laid down in Annex XI, Item 1.5, of Regulation (EC) No 1907/2006, whereby substances may be considered as a category provided that their physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity, the substances listed below are allocated to the category of SCAE C2-C8.

Members of the SCAE C2-C8 Category:

EC No.

CAS No.

Chemical name

Alcohol Carbon No.

Fatty acid Carbon No.

Total Carbon

MW

208 -868-4

544-35-4 (b)

Ethyl linoleate

2

18

20

308.50

203-889-5

111-62-6

Ethyl oleate

2

18

20

310.52

293-054-1

91051-05-7

Fatty acids, essential, ethyl esters

2

14 - 22

16 - 24

252.39-368.64

233-560-1

10233-13-3

Isopropyl laurate

3

12

15

242.41

203-751-4

110-27-0

Isopropyl myristate

3

14

17

270.46

205-571-1

142-91-6

Isopropyl palmitate

3

16

19

298.51

203-934-9

112-10-7

Isopropyl stearate

3

18

21

326.56

269-023-3

68171-33-5 (a)

Isopropyl isostearate

3

18

21

326.56

203-935-4

112-11-8

Isopropyl oleate

3

18

21

324.55

292-962-5

91031-58-2

Fatty acids, C16-18, isopropyl esters

3

16 - 18

19 - 21

312.54-326.57

264-119-1

63393-93-1

Fatty acids, lanolin, isopropyl esters

3

10 - 29

13 - 32

214.34-480.85

204-666-5

123-95-5

butyl stearate

4

18

22

340.59

267-028-5

67762-63-4

Fatty acids, tall-oil, butyl esters

4

18

22

423.72

287-039-9

85408-76-0

Fatty acids, C16-18, Bu esters

4

16 - 18

20 - 22

312.53-340.58

284-863-0

84988-74-9

Fatty acids, C16-18 and C18-unsatd., Bu esters

4

16 - 18

20 - 22

312.53- 340.58

 

163961-32-8

Fatty acids, C16-18 and C18 unsatd. branched and linear, butyl esters

4

16 - 18

20 - 22

312.54- 340.58

211-466-1

646-13-9

Isobutyl stearate

4

18

22

340.59

288-668-1

85865-69-6

Fatty acids, C16-18, iso-Bu esters

4

16 - 18

20 - 22

312.54- 340.60

84988-79-4

84988-79-4

Fatty acids, C16-18 and C18-unsatd., iso-Bu esters

4

16 - 18

20 - 22

312.54- 340.60

228-626-1

6309-51-9

Isopenthyl laurate Dodecanoic acid, 2-methyl butyl ester

5

12

17

270.46

694-886-1

1365095-43-7

Isopentyl decanoate and octanoate

5

8 - 10

13 - 15

214.344- 242.40

251-932-1

34316-64-8

Dodecanoic acid, hexyl ester

6

12

18

284.49

218-980-5

2306-88-9

octyl octanoate

8

8

16

256.42

 

84713-06-4

Dodecanoic acid, isooctyl ester

8

12

20

312.53

243-697-9

20292-08-4

2-Ethylhexyl laurate

8

12

20

312.53

692-946-1

649747-80-8

Fatty acids, C8-10, 2-ethylhexyl esters

8

8 - 10

16 - 18

256.42-284.48

603-931-6

135800-37-2

Fatty acids, C8-16, 2-ethylhexyl esters

8

12 - 14

20 - 22

256.42-368.65

249-862-1

29806-73-3

2-ethylhexyl ester palmitate

8

16

24

368.64

 

22047-49-0

2-Ethyl hexyl Stearate

8

18

26

396.69

295-366-3

92044-87-6

Fatty acids, coco, 2-ethylhexyl esters

8

12 - 18

20 - 26

312.53-340.60

292-951-5

91031-48-0

Fatty acids, C16-18, 2-ethylhexyl esters

8

16 - 18

24 - 26

368.65-396.70

285-207-6

85049-37-2

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

8

16 - 18

24 - 26

368.65-396.70

247-655-0

26399-02-0

2-Ethylhexyl oleate

8

18

26

394.67

261-819-9

59587-44-9

2-ethylhexyl nonanoate

8

9

17

270.45

297-443-7

93572-14-6

 

Fatty acids, soya, 2-ethylhexyl esters

8

 

16 - 18

24 - 26

368.65-396.70

(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.

For all category members registered under REACh a full data set for each endpoint is provided. For substances not subject to the current REACh Phase-in registration, lack of data for a given endpoint is indicated by "--".

 

The available data allow 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. For a detailed review of the data matrix please refer to the category justification attached in section 13 in IUCLID.

 

Aquatic toxicity

Short-term aquatic toxicity data is available for all trophic levels within the SCAE C2-C8 category. Long-term data is available for aquatic invertebrates and algae. Based on the experimental data, the category members have low toxicity to aquatic organisms. Additionally, the exposure concentrations of aquatic organisms are very low, due to the low water solubility. In both short and long term studies, generally, no effects occurred up to the water solubility limit, with some exceptions which are discussed below. Due to their very poor water solubility, the members of the SCAE C2-C8 category are difficult substances for aquatic testing. If undissolved test material is not properly removed from the test vessels, it may cause physical effects, such as immobilisation of daphnia by getting trapped into an oil film or decreasing algal growth by increased turbidity of the test solution. Such effects do not reflect systemic toxicity of the test substance towards the organisms.

Experimental data are generally available for category members with fatty acids up to C18, and datagaps can be filled by interpolation, with the exception of one UVCB substance; Fatty acids, lanolin, isopropyl esters (CAS 63393-93-1), which contains fatty acids of chain length from C10 to C29. As aquatic tests with the shorter category members were already associated with practical difficulties, due to the low water solubility, sometimes leading to ambiguous results, testing this substance was not considered scientifically necessary for an accurate hazard assessment. It is foreseeable that the longer chain leads to an even lower solubility in water and probably to higher adsorption potential. Since Fatty acids, lanolin, isopropyl esters is also readily biodegradable, it is expected to be removed from waste water in sewage treatment plants, through rapid biodegradation and adsorption, as all other category members. All fatty acid alcohol esters are expected to be hydrolysed by lipases (Mattson and Volpenhein, 1972; and references therein), resulting free fatty acids and alcohols, which are absorbed from the intestine into the blood stream. Fatty acids are either metabolised via the β-oxidation pathway in order to generate energy for the cell or reconstituted into glyceride esters and stored in the fat depots in the body.

For fatty acids up to C22, beta-oxidation generally takes place in the mitochondria, resulting to the final product acetyl-CoA, which directly enters the citric acids cycle (Berg, 2002). Beta-oxidation of longer fatty acids takes place in the peroxisomes and is incomplete (Reddy and Hashimoto, 2001; Singh et al., 1987; Le Borgne and Demarquoy, 2012; and references therein). It gives rise to medium chain acyl-CoA, which are then taken in charge by the carnitine octanoyl transferase and converted into acyl-carnitine that can leave the peroxisome and, at least for some of them, may be fully oxidized in the mitochondria (Le Borgne and Demarquoy, 2012; and references therein). Peroxisomal β-oxidation has also been shown to take place in fish, mussels and algae (Rocha et al., 2003; and references therein; Frøyland et al., 2000; Bilbao et al., 2009; Winkler et al., 1988). Consequently, despite the differences in fatty acid metabolism, Fatty acids, lanolin, isopropyl esters (CAS 63393-93-1), can be fully metabolised by aquatic organisms and is thus not expected to differ from the rest of the category in terms of toxicity to aquatic organisms. A read-across approach to other category members is therefore justified.

 

Short term toxicity to fish for the SCAE C2-C8 category members

The assessment of short-term toxicity to fish is based on 17 valid, reliable studies available within the category. Generally, no effects occurred up to the limit of water solubility, with the exception of one study. In this study, conducted with dodecanoic acid, hexyl ester (CAS No. 34316-64-8), a LC50 of 2200 mg/L is reported. However, the test concentrations in this study were far above the saturation limit of the test substance, and undissolved test material was not removed from the test solutions. The sudden increase in mortality from 0% at concentrations 100 – 1000 mg/L to 70% at 3000 mg/L is better explained by a physical effect, caused by the amount of undissolved material in the test solution, rather than a systemic toxic effect.Hence, it can be assumed that no toxic effects occurred up to the limit of water solubility in the available short-term fish tests.

The available studies cover the variability of the category with different alcohol and fatty acid chain lengths up to C18 (MW 242.41 - 394.69 mg/L). The data gaps within the category can thus be filled by interpolation. Only the smallest constituent of the UVCB isopentyl decanoate and octanoate (CAS No. 1365095-43-7) (MW 214.34 g/mol) and the larger constituents of Fatty acids, lanolin, isopropyl esters (CAS 63393-93-1) (MW 466.82 g/mol) are outside the size range of the tested substances. For the smaller substance read across from larger substances is considered acceptable for aquatic toxicity, since its water solubility is as low as for the tested substances (< 0.05 mg/L). Read-across in the case of Fatty acids, lanolin, isopropyl esters, as is explained above, is also considered fully reliable due to the similar physiochemical properties and trends (increasing water insolubility with increasing chain length, increasing adsorption potential etc.).

 

Long term toxicity to fish for the SCAE C2-C8 category members

There are no long-term toxicity to fish studies available for the SCAE C2-C8 category. However, short-term studies available for fish, daphnia and algae, all indicate a low potential for aquatic toxicity. Moreover, the reliable NOECs obtained from algal growth studies and daphnia reproduction studies are all above the limit of water solubility. Additionally, the aquatic concentrations of these substances are expected to be very low. This assumption of low environmental exposure is based primarily on the lack of water solubility and also on the fact that all substances are readily biodegradable and have high adsorption potential (log Koc 3.0 – 7.9, MCI method, KOCWIN v2.00), and are thus expected to be eliminated in sewage treatment plants to a high extent. In the aquatic environment, the concentration in the water phase will be reduced by biodegradation and adsorption to solid particles and to sediment. If exposure would occur, food ingestion is likely to be the main uptake route of the SCAE C2-C8 category members in fish, since the substance will be adsorbed to solid particles potentially ingested by fish. In the case of ingestion, category members are predicted to undergo metabolism. Studies with rats have shown that esters of primary alcohols, containing from 1 to 18 carbon atoms, with fatty acids, containing from 2 to 18 carbon atoms, are hydrolysed by pancreatic lipases. Measured rates of enzyme catalysed hydrolysis varied between 2 and 5 µeq/min/mg enzyme for the different chain lengths (Mattson and Volpenhein, 1972; and references therein). The longer esters possibly present in the UVCB substance Fatty acids, lanolin, isopropyl esters (CAS 63393-93-1), are also expected to be hydrolysed. Only moderate differences in the rate of hydrolysis were observed for different long chain saturated and unsaturated fatty-acid esters, in studies investigating the fatty acid specificity of pancreatic lipases (Macrae and Hammond, 1985; and references therein). Exceptionally poor substrates were esters of fatty acids containing a double bond or a bulky substituent close to the carboxyl group, probably due to steric reasons. However, Fatty acids, lanolin, isopropyl esters (CAS 63393-93-1) only contains saturated fatty acids and branching may only occur on the penultimate or the ante-penultimate carbon atom, i.e. far from the carboxyl group.All esters of the SCAE C2-C8 category are thus expected to be hydrolysed by lipases. The resulting free fatty acids and alcohols are absorbed from the intestine into the blood stream. The alcohols are metabolised primarily in the liver through a series of oxidative steps, finally yielding carbon dioxide (Berg et al., 2001; HSDB). Fatty acids are either metabolised via the beta-oxidation pathway in order to generate energy for the cell or reconstituted into glyceride esters and stored in the fat depots in the body (Berg et al., 2001). For fatty acids up to C22, beta-oxidation generally takes place in the mitochondria, resulting in the final product acetyl-CoA, which directly enters the citric acids cycle (Berg, 2002). Beta-oxidation of longer fatty acids takes place in the peroxisomes and is incomplete (Reddy and Hashimoto, 2001; Singh et al., 1987; Le Borgne and Demarquoy, 2012; and references therein). It gives rise to medium chain acyl-CoA, which are then taken in charge by the carnitine octanoyl transferase and converted into acyl-carnitine that can leave the peroxisome and, at least for some of them, may be fully oxidized in the mitochondria (Le Borgne and Demarquoy, 2012; and references therein). Peroxisomal β-oxidation has also been shown to take place in fish, mussels and algae (Rocha et al., 2003; and references therein; Frøyland et al., 2000; Bilbao et al., 2009; Winkler et al., 1988). Metabolic pathways in fish are generally similar to those in mammals. Lipids and their constituents, fatty acids, are in particularly a major organic constituent of fish and play major roles as sources of metabolic energy (Tocher, 2003).

In conclusion, SCAE C2-C8 category members will be mainly taken up by ingestion and digested through common metabolic pathways, providing a valuable energy source for the organism, as dietary fats. Long-term toxic effects on fish are therefore not to be expected.

 

Short term toxicity to aquatic invertebrates for the SCAE C2-C8 category members

The assessment of short-term toxicity to aquatic invertebrates is based on 13 valid, reliable studies available for the category. Generally, no effects occurred up to the limit of water solubility. In one study with isopropyl myristate (CAS No. 110-27-0), the EC50 was determined to be 100 mg/L, but the report states that mobility of daphnids was impeded by floating test material. For the marine test conducted with Fatty acids, C16-18 and C18 unsaturated, 2-ethylhexyl esters (CAS No. 85049-37-2) an EC50 value of 2047 mg/L, was reported for Acartia tonsa. Although the test solutions were prepared as water accommodated fractions (WAF), by siphoning, it is possible that some undissolved material was present in the test solutions. Effects were observed at the loading of 1000 mg/L (lowest test concentration), whereas in the range-finding test, no mortality occurred at concentrations 10 – 100 mg/L, which is already far above the saturation limit of the substance. This indicates that mortality at higher loadings may be due to undissolved test material in the test solutions. In a further study conducted with octyl octanoate (CAS No. 2306-88-9) some immobilisation occurred, but the EC50 was determined to be > 100 mg/L nominal (i.e. greater than the water solubility). It is not clear if the effects were physical or systemic, although the evidence suggests physical. Oil drops were observed on the water surface of the test solutions and the dissolved solution was pipetted off to test vessels. However, this automatically leads to the assumption that all test concentrations (as was particularly the case for 10 mg/L) may have been contaminated to a certain degree during this pipetting process. Additionally, the highest measured test concentration (23.6 mg/L) was far higher than the water solubility of the substance. This again indicates that some errors or super saturation may have occurred (e.g. formation of microemulsions). Although the study is considered reliable (Klimisch score 2), the results should be treated with caution for read-across purposes. In a further study conducted with ethyl linoleate (CAS No. 544-35-4), a measured EC50 of 0.074 mg/L is reported. However, it is reported that a floating layer was formed and that daphnids were trapped at the surface. In order to exclude physical effects, a limit test with 100 mg/L was performed, using a net to keep the daphnids away from the surface. Again, immobilisation occurred, but it is not clear if it was due to physical or systemic effects. Since an EC50 value cannot be derived from a limit test, and the results are ambiguous, this study cannot be used for assessment. However based on the available reliable data, it can be concluded that the toxic potential of short chain alcohol esters to both marine and freshwater aquatic invertebrates is low, and the EC50 is greater than the water solubility limit.

The available studies cover the variability of the category with different alcohol and fatty acid chain lengths (MW 256.42 – 396.7 g/mol). The data gaps within the category can thus be filled by interpolation. Only the smallest constituent of the UVCB isopentyl decanoate and octanoate (CAS No. 1365095-43-7) (MW 214.34 g/mol) and the larger constituents of Fatty acids, lanolin, isopropyl esters (CAS 63393-93-1) (MW 466.82 g/mol) are outside the size range of the tested substances (MW 214.34 mg/L). However, data is available for octyl octanoate, which only differs from isopentyl octanoate with the slightly longer alcohol. Since the two substances have very similar structures and physicochemical properties (water solubility < 0.05 mg/L, log Kow 6.2 - 6.8), read across is considered acceptable for aquatic toxicity. Read-across in the case of Fatty acids, lanolin, isopropyl esters, as is explained above, is also considered fully reliable due to the similar physiochemical properties and trends (increasing water insolubility with increasing chain length, increasing adsorption potential etc.).

 

Long term toxicity to aquatic invertebrates for the SCAE C2-C8 category members

There are four long -term studies available within the category. The studies conducted with the substances isopropyl myristate (CAS No. 110-27-0) and Fatty acids, C16-18 and C18 unsaturated, isobutyl esters (CAS No. 84988-79-4) showed that the test substance had no effect on the reproduction or mortality of the test organisms. The substances represent both ends of the category in terms of molecular weight (270.46 and 338.57 g/mol), and provide data for both saturated and unsaturated fatty acids. Since all category members have low solubility (< 0.05 - <0.15 mg/L) and are expected to follow the same metabolic pathways, there is no reason to expect toxic effects for other category members. Although the two additional studies are considered reliable, they do not allow a precise determination of a NOEC. In one study conducted with Fatty acids, C8-16, 2-ethylhexyl esters (CAS No. 135800-37-2), 10% mortality of parent animals and a significantly reduced reproduction were observed at 100 mg/L. The test was only conducted at concentrations 1 and 100 mg/L, and a meaningful NOEC could therefore not be derived. In a further study with 2-ethylhexyl oleate (CAS No. 26399-02-0), no effect on reproduction was observed at 100 mg/L but 90% mortality of parent animals, although this was assumed by the author to be a result of sample contamination. Since only concentrations 1 and 100 mg/L were tested, and the report indicated problems in the test performance, this study was considered only to be reliable for the overall assessment in assuming that the NOEC is > 1 mg/L. Nevertheless, the overall hazard assessment of the category is based on the two reliable studies for isopropyl myristate (CAS No. 110-27-0) and Fatty acids, C16-18 and C18 unsaturated, isobutyl esters (CAS No. 84988-79-4), which clearly show that the substances had no long-term effects on the aquatic invertebrates.

Toxicity to algae for the SCAE C2-C8 category members

The assessment of toxicity to algae is based on ten valid, reliable studies available for the category. In most studies, no effects occurred up to the limit of water solubility. In a study conducted with Fatty acids, C16-18, 2-ethylhexyl (CAS No. 91031-48-0) an EL50 of 300 mg/L was reported for the freshwater alga S. subspicatus. However, the test concentrations were far above the water solubility of the test substance, and undissolved material was not removed from the test solutions. Physical effects caused by undissolved test material can thus not be excluded.In a study conducted with Fatty acids, C16-18 and C18 unsaturated, 2-ethylhexyl esters (CAS No. 85049-37-2), an EL50 of 281.37 mg/L was reported for the marine alga Skeletonema costatum.In this case, the test solutions were prepared as water accommodated fractions (WAF), but the presence of undissolved test material, causing physical effects, can still not be excluded.It is likely that no toxic effects on algae occurred in the available studies, as shown by most of the studies. However, the possibility of a very low toxicity in the case of Skelatonema costatum (EL50 281.37 mg/L) cannot be excluded.In a further study with ethyl linoleate (CAS No. 544-35-4), algal growth was inhibited at a concentration of 100 mg/L. However, the test solutions at 100 mg/L were reported to be hazy, which may have reduced the light in the vessels and thereby effecting the growth of algae.

The available studies cover the variability of the category with different alcohol and fatty acid chain lengths (MW 256.42 – 396.7 g/mol). The data gaps within the category can thus be filled by interpolation. Only the smallest constituent of the UVCB isopentyl decanoate and octanoate (CAS No. 1365095-43-7) (MW 214.34 g/mol) and the larger constituents of Fatty acids, lanolin, isopropyl esters (CAS 63393-93-1) (MW 466.82 g/mol) are outside the size range of the tested substances (MW 214.34 mg/L). However, data is available for octyl octanoate, which only differs from isopentyl octanoate with the slightly longer alcohol. Since the two substances have very similar structures and physicochemical properties (water solubility < 0.05 mg/L, log Kow 6.2 - 6.8), read across is considered acceptable for aquatic toxicity. Read-across in the case of Fatty acids, lanolin, isopropyl esters, as is explained above, is also considered fully reliable due to the similar physiochemical properties and trends (increasing water insolubility with increasing chain length, increasing adsorption potential etc.).
 

Toxicity to microorganisms for the SCAE C2-C8 category members

The assessment of toxicity to microorganisms is based on seven valid, reliable studies available for the category. No effect on microbial growth occurred in any of the studies, and EC50 values were > 100 mg/L.
The available studies cover the variability of the category with different alcohol and fatty acid chain lengths (MW 256.42 – 396.7 g/mol). The data gaps within the category can thus be filled by interpolation. Only the smallest constituent of the UVCB isopentyl decanoate and octanoate (CAS No. 1365095-43-7) (MW 214.34 g/mol) and the larger constituents of Fatty acids, lanolin, isopropyl esters (CAS 63393-93-1) (MW 466.82 g/mol) are outside the size range of the tested substances (MW 214.34 mg/L). However, data is available for octyl octanoate, which only differs from isopentyl octanoate with the slightly longer alcohol. Since the two substances have very similar structures and physicochemical properties (water solubility < 0.05 mg/L, log Kow 6.2 - 6.8), read across is considered acceptable for aquatic toxicity. Read-across in the case of Fatty acids, lanolin, isopropyl esters, as is explained above, is also considered fully reliable due to the similar physiochemical properties and trends (increasing water insolubility with increasing chain length, increasing adsorption potential etc.).

General conclusion
Finally, the data available on aquatic toxicity for the SCAE C2-C8 category show a clear, consistent pattern of no toxic effects up to the limit of water solubility. In some individual cases, effects were observed, but these are assumed to be physical effects based on the applied methods rather than intrinsic toxicity. However, even the determined EL50 values indicate a very low level of toxicity, if at all (EL50 > 100 mg/L nominal). It can thus be concluded that members of the SCAE C2-C8 category are not harmful to aquatic organisms as indicated by measured EC50 values clearly above the water solubility limit of the category members.
SCAE C2-C8 is a robust category with a large amount of reliable, consistent data, throughout the category. In each case of read-across, the best suited (highest degree of structural similarity, nearest physico-chemical properties) read-across substances were entered into IUCLID. Nevertheless, as can be seen in the data matrix of the category justification in Section 13, all reliable data in the category support the hazard assessment of each category member, by showing a consistent pattern of results.
 

References:

Berg, J.M., Tymoczko, J.L. and Stryer, L., 2002, Biochemistry, 5th edition, W.H. Freeman and Company

Bilbao, E., Cajaraville, M.P., Cancio, I. (2009), Cloning and expression pattern of peroxisomal β-oxidation genes palmitoyl-CoA oxidase, multifunctional protein and 3-ketoacyl-CoA thiolase in mussel Mytilus galloprovincialis and thicklip grey mullet Chelon labrosus, Gene, 443(1-2): 132-42

Frøyland, Lie, Berge (2000), Mitochondrial and peroxisomal β-oxidation capacities in various tissues from Atlantic salmon Salmo salar, Aquaculture Nutrition, 6 (2): 85-89

Gubicza, L., Kabiri-Badr, A., Keoves, E., Belafi-Bako, K. (2000): Large-scale enzymatic production of natural flavour esters in organic solvent with continuous water removal. Journal of Biotechnology 84(2): 193-196

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