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Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

There is only limited data available for the aquatic toxicity of the target substanceFatty acids, C16-18, stearyl esters (CAS 85536-04-5). Therefore, the aquatic toxicity of the target substance was assessed by means of a read-across approach, through which additional data from two structurally and chemically closely related source substances was compiled in order to fulfill the standard information requirements laid down in Annex VIII of REACh Regulation (EC) No 1907/2006. Read-across was performed in accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5.

According to Article 13 of Regulation (EC) No 1907/2006 "General Requirements for Generation of Information on Intrinsic Properties of substances", information on intrinsic properties of substances may be generated by means other than tests e.g. from information from structurally related substances (grouping or read-across), provided that conditions set out in Annex XI are met. In Annex XI, "General rules for adaptation of this standard testing regime set out in Annexes VII to X”, it is stated that “substances whose physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity may be considered as a group, or ‘category’ of substances. This avoids the need to test every substance for every endpoint and avoids unnecessary animal testing”.

The target substanceFatty acids, C16-18, stearyl esters (CAS 85536-04-5) is a UVCB substance consisting of nine main constituents, most of which are long-chain aliphatic esters composed of saturated linear fatty acids with chain lengths ranging from C14 to C20 and alcohol components with chain lengths mostly ranging from C16 to C18 as well as minor quantities of C20 alcohols (< 5%). In the present dossier, the target substance will be assessed on the basis of aquatic toxicity data compiled from the source substances Fatty acids, C16-18, 2-hexyldecyl esters (CAS 101227-09-2) and 2-octyldodecyl isooctanoate (CAS 93803-87-3). Both source substances are UVCB substances.The source substanceFatty acids, C16-18, 2-hexyldecyl esters (CAS 101227-09-2) is characterized by linear C14 – C18 fatty acids and branched C16 – C18 alcohols.The source substance2-octyldodecyl isooctanoate (CAS 93803-87-3) consists of branched C18 fatty acids and linear C20 alcohols.The source substances were selected on the basis of structural similarities and similarities in properties and/or activities to the target substance, with due regard to requirements for adequacy and reliability of data. Therefore, the source substances are considered suitable representatives for the assessment of the aquatic toxicity of the target substance. Based on the high degree of similarity between the structural and physico-chemical properties of the target and selected source substances, it is assumed that the target substance will exhibit a similar ecotoxicological profile as the source substances. Where applicable, environmental and human health effects of the target substance are predicted by interpolation or extrapolation from source substance data in accordance with Annex XI, Item 1.5, of Regulation (EC) No 1907/2006. A detailed read-across justification is provided in IUCLID section 13.

 

By means of the read-across approach, guideline studies from the source substances are available for the short-term toxicity of the target substance to fish, aquatic invertebrates and algae as well as for the long-term toxicity to algae. Due to the extremely low water solubility of the target substance (< 0.507 mg/L, OECD 105), long-term testing on aquatic invertebrates was considered necessary to fully assess the potential aquatic hazard of the target substance. In addition, one experimental study is available for the toxicity to microorganisms.

All the available aquatic toxicity studies were performed in compliance with GLP and most of the studies prepared the test solutions as Water Accommodated Fractions (WAFs) due to the poor solubility of the tested substances.

 

For the short-term toxicity to fish two studies are available. The available study with the source substance Fatty acids, C16-18, 2-hexyldecyl esters (CAS 101227-09-2) was conducted according to ISO 7346-1 and the study with source substance 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) was conducted according to OECD 203. After 96 h, no mortality was recorded in both studies and an LC50 (96 h) of > 10000 mg/L (nominal) and an LL50 (96 h) of > 100 mg/L (nominal) were derived, respectively. Thus, no short-term toxic effects to fish were recorded up to the limit of water solubility of the tested substances.

For the short-term toxicity to aquatic invertebrates two studies are available. The available study with the source substance Fatty acids, C16-18, 2-hexyldecyl esters (CAS 101227-09-2) was conducted according to EU method C.2 and the study with the source substance 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) was conducted according to OECD guideline 202. After 48 h, no effects on mobility were recorded in either study and it was concluded that no short-term toxicity to aquatic invertebrates occurs up to the limit of water solubility of the tested substances.

For the long-term toxicity to aquatic invertebrates one study with the source substance 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) is available, which consists of a laboratory statement explaining that a long-term study is technically not feasible due to the specific properties of the test item. The poor water solubility and high log Kow (> 7.0) preclude the preparation of adequate test solutions and the chemical analysis of actual test item concentrations, the latter of which is a required acceptability criterion for a guideline test. Thus, a 21-day reproduction test according to OECD 211 cannot be performed. In addition, based on the particular substance characteristics it is considered highly unlikely that bioavailable concentrations of the test item will ever occur in the water phase, i.e. that high enough concentrations to induce any acute or chronic effects in aquatic organisms are ever attained.

The toxicity to aquatic algae was assessed in one study with the source substance 2-octyldodecyl isooctadecanoate (CAS 93803-87-3), which was conducted according to OECD guideline 201 and resulted in an EL50 (72 h) of > 100 mg/L and a NOELR (72 h) of ≥ 100 mg/L. Thus, it was concluded that no toxicity to aquatic algae occurs up to the limit of water solubility of the tested substance.

The toxicity to microorganisms was assessed on the basis of the positive control of a biodegradation studywith the source substance2-octyldodecyl isooctadecanoate(CAS 93803-87-3) conducted according to OECD guideline 301 B. A substance can be assumed to be not inhibitory to aquatic microorganisms, if in the toxicity control of a ready biodegradation test, more than 25% degradation based on CO2 evolution occurred within 14 days (OECD guideline 301). After 14 d incubation, the toxicity control attained 78.1% degradation and it was thus concluded, that the substance is not toxic to aquatic microorganisms.

In summary, the compiled data for short-term toxicity to all three trophic levels (fish, aquatic invertebrates and algae) and long-term toxicity to one trophic level (aquatic algae) neither indicate any short-term nor long-term toxicity to aquatic organisms up to the limit of water solubility. Moreover, it is anticipated that a long-term toxicity test to aquatic invertebrates is technically not feasible due to the particular substance characteristics shared by both the source and target substances (poor solublity and high hydrophobicity). In addition, it is considered highly unlikely that bioavailable concentrations of the test item will ever occur in the water phase, i.e. that concentrations high enough to induce any acute or chronic effects in aquatic organisms are every attained due to the particular substance characteristics. Furthermore, no inhibitory effects towards aquatic microorganisms of activated sludge were recorded. Based on the high degree of structural and chemical similarity between the target and the selected source substances, the target substance is expected to exhibit a similar ecotoxicological profile as the source substances.

Furthermore, the target substance is expected to be eliminated from sewage treatment plants to a high extent due to its ready biodegradability (68.1 – 71.7% in 28 d, OECD 301 B/ 90% in 28 d, OECD ISO 10708) and its high adsorption potential (log Koc > 5.0, KOCWIN v.2.00). Thus, release to the aquatic environment and subsequent exposure of sediment is therefore highly unlikely. Against this background, the overall potential for chronic exposure and for bioaccumulation in aquatic organisms is judged to be very low.

Therefore, it is concluded that the target substanceFatty acids, C16-18, stearyl esters (CAS 85536-04-5)presumably does not cause short-term or long-term toxicity to aquatic organisms up to the limit of water solubility (< 0.507 mg/L, OECD 105) and is not expected to affect the degradation process in sewage treatment plants.