2-octyldodecyl myristate

Toxicity to microorganisms

Description of key information

NOEC of ≥ 14.2 mg/L (OECD 301B)

Additional information

Since no studies investigating the toxicity of 2-octyldodecyl myristate (CAS 22766-83-2) to activated sludge microorganisms are available, in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5 a read-across to the structurally related source substance 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) was conducted. The source substance is representative to evaluate the short-term toxicity of the target substance to fish. The target substance is characterised as an ester of C18 iso branched fatty acid esterified with 2-octyldodecan-1-ol. The source substance is structurally very similar to the target substance. 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) is characterised by a longer fatty acid chain length (C18 iso branched) and by the same alcohol component (2-octyldodecan-1-ol).This read-across is justified in detail in the overall summary (IUCLID Section 6.1) and within the analogue 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 substance was used for the assessment.
Since no studies on the toxicity to aquatic microorganisms are available a ready biodegradability study from the source substance 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, 2012). 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 the source substance 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 results from a structurally related read-across substance (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) which is characterised by a comparable structure, it can be concluded that 2-octyldodecyl myristate will not exhibit effects on activated sludge microorganisms and does not inhibit the microbiological process of degradation in sewage treatment plants.