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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

NOEC (14 d): ≥ 14.2 mg/L for activated sludge microorganisms (OECD 301B)

Key value for chemical safety assessment

Additional information

Since no studies investigating the toxicity to microorganisms of Fatty acids, C16-18, 2-octyldodecyl esters (CAS 96690-38-9) are available for this endpoint, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read across to the structurally related category member 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) was conducted. The read-across substance is characterized by the same alcohol component (2-octyldodecan-1-ol) and a very similar fatty acid (C16-18 compared to C18iso (target)). This read-across is justified in detail in the overall summary (IUCLID Section 6.1) and within the category justification in IUCLID Section 13. In this case of read-across, the best suited (highest degree of structural similarity, nearest physico-chemical properties) read-across substances were used for the assessment. Nevertheless, as it can be seen in the data matrix of the category justification in section 13 and the overall summary, all reliable data in the category support the hazard assessment of each category member by showing a consistent pattern of results.

Since no studies on the toxicity to aquatic microorganisms are available for the read-across substance 2-octyldodecyl isooctadecanoate a ready biodegradability study is used to derive a NOEC for the toxicity to aquatic microorganisms. If a compound degrades well in a ready biodegradability test, or does not inhibit the degradation of a positive control at a certain concentration, this concentration can be used as a NOEC value. This approach is in accordance with the Guidance on information requirements and chemical safety assessment (Chapter R.7b: Endpoint specific guidance, ECHA 2008). 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). For 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) a biodegradation test conducted according to OECD guideline 301B is available (Desmares-Koopmans, 1998). The test includes a toxicity control, which contains 14.2 mg/L of the test substance and 39.85 mg/L of the reference material. The toxicity control attained 78.1% degradation after 14 days of incubation. Hence, the substance is not toxic to aquatic microorganisms and a NOEC of ≥ 14.2 mg/L was derived.Based on the available result from one structurally related read-across substance (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) which is characterized by a similar ecotoxicological profile and comparable structure, it can be concluded that Fatty acids, C16-18, 2-octyldodecyl esters will not exhibit effects to activated sludge microorganisms.