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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reason / purpose:
read-across source
Duration:
48 h
Dose descriptor:
EL50
Effect conc.:
> 86 mg/L
Nominal / measured:
nominal
Conc. based on:
other: Water Accommodated Fraction (WAF)
Basis for effect:
mobility
Remarks on result:
other:
Remarks:
Source: CAS 93803-87-3, Croda, 1998, D. magna, 48 h
Details on results:
- Mortality of control: no
- Effect concentrations exceeding solubility of substance in test medium: The test solutions at 86 mg/L (nominal) exceeded the maximum water solubility of the test substance.
Results with reference substance (positive control):
- Results with reference substance valid? yes
- EC50/LC50: 48 h EC50 was 0.5 mg/L (95% Confidence Limit: 0.4 - 0.6 mg/L)
Conclusions:
No effects up to the limit of water solubility (< 0.05 mg/L; OECD 202, D. magna); read-across
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
yes
Remarks:
Only two replicates were used instead of four as recommended.
Qualifier:
according to
Guideline:
ISO 6341 (Water quality - Determination of the Inhibition of the Mobility of Daphnia magna Straus (Cladocera, Crustacea))
Deviations:
yes
Remarks:
The pH of the dilution water was slightly higher (8.0 +/- 0.2).
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test solutions were prepared separately and mixed with test medium for a defined period. Subsequently, the test solutions were allowed to stabilize in a separating funnel. The water phase in the middle of the separating funnel was used for testing and was identified as the Water Accommodated Fraction (WAF).
- Eluate: no
- Differential loading: yes
- Controls: yes, water control
- Evidence of undissolved material: All final test solutions were clear and colourless.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: water flea
- Age at study initiation: < 24 h
- Method of breeding: Daphnia were held at a temperature of 18 – 22 °C. A new batch was started with newborn animals, i.e. less than 3 d old, by placing about 250 of them into 30 L of medium in an all-glass culture vessel. The maximum age of culture was 4 weeks. After 7 d of cultivation half of the medium was renewed. Daphnids were fed daily with a suspension of fresh water algae.
- Feeding during test: no
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Test temperature:
21.3 °C
pH:
7.8 - 7.9
Dissolved oxygen:
8.1 - 8.6 mg O2/L
Nominal and measured concentrations:
Nominal: 0, 86 mg/L (corresponding to 100 µL/L)
Details on test conditions:
TEST SYSTEM
- Test vessel: all-glass vessels
- Material, size, fill volume, headspace: all-glass, 100 mL, Fill volume: 80 mL, Headspace: 20 mL
- Aeration: no
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Medium was prepared according to ISO guideline in milli-RO water
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Photoperiod: 16 h light / 8 h dark

EFFECT PARAMETERS MEASURED: Immobility was recorded after 24 and 48 h.

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: control, WAFs at 10 and 100 mg/L (range finding study 1); control, WAFs at 0.86 and 8.6 mg/L (range finding study 2)
- Results used to determine the conditions for the definitive study: At WAFs prepared at 10 and 100 mg/L daphnids trapped at the surface of test solutions. At WAFs prepared at 0.86 and 8.6 mg/L the stabilisation period was increased to 24 h to overcome daphnids becoming trapped at the surface. No effects were observed in the second range-finding study.
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
48 h
Dose descriptor:
EL50
Effect conc.:
> 86 mg/L
Nominal / measured:
nominal
Conc. based on:
other: Water Accommodated Fraction (WAF)
Basis for effect:
mobility
Details on results:
- Mortality of control: no
- Effect concentrations exceeding solubility of substance in test medium: The test solutions at 86 mg/L (nominal) exceeded the maximum water solubility of the test substance.
Results with reference substance (positive control):
- Results with reference substance valid? yes
- EC50/LC50: 48 h EC50 was 0.5 mg/L (95% Confidence Limit: 0.4 - 0.6 mg/L)

Description of key information

No effects up to the limit of water solubility (1.39 µg/L, 20 °C; OECD 202, D. magna); read-across

Key value for chemical safety assessment

Additional information

There is no study available assessing the short-term toxicity of the target substance Isohexadecyl 12-[(1-oxooctadecyl)oxy]octadecanoate (CAS 97338-28-8) to aquatic invertebrates. Therefore, read-across to the structurally related source substance 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) was conducted in accordance with Regulation (EC) No. 1907/2006 Annex XI, 1.5. The source substance is characterized by similar but smaller fatty acid esters and is therefore considered a suitable representative for the assessment of the short-term toxicity of the target substance to aquatic invertebrates. A detailed justification of the analogue approach is provided in IUCLID section 13.

One GLP Guideline study is available investigating the short-term toxicity of 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) to aquatic invertebrates is available (Croda, 1998). The study was performed according to OECD 202 with Daphnia magna. A Water Accommodated Fraction of nominal 86 mg/L was prepared and tested under static conditions (limit test). A chemical analysis of the test substance concentrations in the test vessels was not possible since no applicable method could be established due to the very low water solubility to detect test concentrations.

After 48 h, no immobilisation was observed and therefore an EL50 of > 86 mg/L (nominal) was derived. Hence, it can be concluded that no toxicological effects on aquatic invertebrates are expected up to the limit of water solubility for2-octyldodecyl isooctadecanoate.

Based on the structural and chemical similarity of the target and source substance, the target substance is expected to exhibit a similar ecotoxicological profile. Therefore, it can be concluded that the target substance Isohexadecyl 12-[(1-oxooctadecyl)oxy]octadecanoate (CAS 97338-28-8) does not cause short-term effects to aquatic invertebrates up to the limit of water solubility. Moreover, experimental studies are a technical challenge due to substance characteristics.