2-octyldodecyl 12-[(1-oxooctadecyl)oxy]octadecanoate

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reason / purpose for cross-reference:

read-across source

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

< 7 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Description of key information

NOEC (21 d) < 7.0 µg/L (nominal, OECD 211, D. magna); read-across

Additional information

No study is available, in which the long-term toxicity of the target substance 2-octyldodecyl 12-[(1-oxooctadecyl)oxy]octadecanoate (CAS 90052-75-8) to aquatic invertebrates was assessed. Therefore, read-across to the structurally related source substance isocetyl stearoyl stearate (CAS 97338-28-8) was conducted in accordance with Regulation (EC) No 1907/2006, Annex XI, 1.5. The source substance is characterized by similar fatty acid chain lengths as well as alcohol components and is therefore considered a suitable representative for the assessment of the chronic toxicity of the target substance to aquatic invertebrates. A detailed analogue approach justification is provided in IUCLID section 13.

In the available study with the source substance, a chronic limit test was performed due to the poor water solubility of the test item. The model organism Daphnia magna was exposed to a limit concentration of 7.0 µg/L test item for 21 d and the test medium was renewed every 2 to 3 d. The test item was applied as water saturated solution prepared in M4 mineral medium. A newly saturated solution was used at each renewal of the treatment solutions. Saturated solutions were obtained by collecting 500 mL volumes from a flow-through (1 mL/min) burette column filled with sand quartz, which had previously been coated with test item. The same coated quartz sand portion was used for the entire test period to produce successive 500 mL water saturated aliquots of saturated test item solutions. Test item concentrations were analytically verified by HPLC-MS at every renewal in old and fresh test medium. At the end of the test, the total number of living offspring produced per live parent animal was assessed.

The calculated mean measured concentration was 7.0 µg/L with a standard deviation of 1.0 µg/L. The measured test item concentrations in old and new medium ranged between 5.5 and 8.8 µg/L, corresponding to 78.5 to 126.5% of the mean measured value. Though the measured test item concentrations were slightly outside the recommended range of 80 to 120% of nominal, the test item was considered to be stable throughout the duration of the test. Outliers were only observed on Day 12 and 14 in new media and at test end in old medium.

After 21 d, no mortality was observed in the limit concentration treatments but the reproductive performance (mean offspring per parent animal) was significantly reduced by 58.5%, resulting in a NOEC (21 d) for reproduction of < 7.0 µg/L (nominal).

Based on the structural and chemical similarity of the target and source substances, the target substance is expected to exhibit a similar ecotoxicological profile as the source substance. Therefore, the NOEC (21 d) of < 7.0 µg/L obtained for the source substance is used as effect value for the long-term toxicity of the target substance 2-octyldodecyl 12-[(1-oxooctadecyl)oxy]octadecanoate (CAS 90052-75-8) to aquatic invertebrates.