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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
March 16 to April 20, 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
2004
GLP compliance:
yes
Test material information:
Composition 1
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Batch 677700
- Expiration date of the lot/batch: 13 June 2018
- Purity: 99.8%
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 10, 18, 32, 56, 100 mg/L
- Sampling method: Samples for possible analysis were taken from all test concentrations and the control at t=0h and t=48h. 0.6 mL were collected from the approximate centre of the test vessels.
- Sample storage conditions before analysis: Samples were stored in a freezer (≤-15°C) until analysis at the analytical laboratory of the Test Facility
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The highest concentration of the test solution (100 mg/L) was prepared via vigorous shaking to completely dissolve test item in medium. Lower test concentrations were prepared by subsequent dilutions of the highest concentration in test medium. All test solutions were clear and colorless at the end of the preparation procedure.
- Controls: Test medium without test item or other additives
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: water flea
- Strain/clone: Straus, 1820
- Source: In-house laboratory culture with a known history
- Age of parental stock: More than two weeks old (at least third generation, obtained by a cyclical parthenogenesis under specified breeding conditions.)
- Feeding during test: No
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
Immobility (ncluding mortality) observed at 24 hrs and at 48 hrs
Hardness:
180 mg/L expressed as CaCO3
Test temperature:
19 to 20°C
pH:
7.9 to 8.2
Dissolved oxygen:
8.7 to 9.1 mg/L
Nominal and measured concentrations:
Nominal concentrations: 10, 18, 32, 56 and 100 mg/L
Measured concentrations: 11, 18, 32, 53, 90 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 60 mL, all-glass
- Material, size, headspace, fill volume: 50 mL of test solution
- Aeration: None
- No. of organisms per vessel: 5 daphnids per vessel
- No. of vessels per concentration (replicates): 4 vessels per concentration
- No. of vessels per control (replicates): 4 vessels per concentration

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: tap water purified by Reverse Osmosis (RO-water, GEON Waterbehandeling, Berkel-Enschot, The Netherlands):

EFFECT PARAMETERS MEASURED:
- At 24 hours and at 48 hours

RANGE-FINDING STUDY
- Test concentrations: 0.10, 1.0 and 10 mg/L
- Results used to determine the conditions for the definitive study: At the limit concentration, 55 and 75% immobility was observed after 24 and 48 hrs of exposure, respectively. Therefore, the expected 24h and 48h-EC50 was between 10 and 100 mg/L
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
57 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 96% CL: 51-65 mg/L
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
83 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% CL: 74-93 mg/L
Details on results:
In the control, no daphnids became immobilised or showed other signs of disease or stress, for example discoloration or unusual behaviour such as trapping at the surface of the medium.
Results with reference substance (positive control):
- Results with reference substance valid? Yes
- Relevant effect levels:
The 24h-EC50 was 0.80 mg/L with a 95% confidence interval between 0.71 and 0.90 mg/L.
The 48h-EC50 was 0.33 mg/L with a 95% confidence interval between 0.29 and 0.38 mg/L.
Reported statistics and error estimates:
Results of the Trimmed Spearman-Karber procedure for calculation of 24hr EC50:
EC50: 83.069 mg/L
Lower 95%-CL: 74.229
Upper 95%-CL: 92.962
Ln LC50: 4.4197
SE(Ln LC50): 0.0563


Results of the Weibull Analysis at 48hr:
EC50 value: 56.607 mg/L
Lower 95%-CL: 50.537
Upper 95%-CL: 65.276
Log EC50: 1.75287
SE Log EC50: 0.02683

Samples taken from all concentrations and the control were analysed. The measured concentrations at the start of the test were at the level of nominal (i.e. 90 – 107% relative to nominal). Measured concentrations remained stable during the exposure (85-90% of initially measured concentrations). Therefore, the effect parameters were expressed in terms of measured concentrations.

 

 The test conditions remained within the limits prescribed in the test plan:

- pH: 6 9, not varying by more than 1.5 units

- oxygen:≥3 mg/L at the end of the test

- temperature: between 19 and 20°C

Validity criteria fulfilled:
yes
Conclusions:
The 48hr-EC50 for daphnia magna exposed to TAOBN was 57 mg/L based on average exposure concentrations (95% confidence interval between 51 and 65 mg/L).

Description of key information

The short-term toxicity of TAOBN to aquatic invertebrates was assessed in a 48-hr immobilisation test of daphnia magna which followed OECD TG 202 (2004). The 48hr EC50 for daphnia magna exposed to TAOBN was 57 mg/L based on average exposure concentrations (95% confidence interval between 51 and 65 mg/L).

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
57 mg/L

Additional information