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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:
2016-01-15 to 2016-02-19
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:
no
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
Qualifier:
according to
Guideline:
other: Guidance document on aquatic toxicity testing of difficult substances and mixtures, OECD series on testing and assessment number 23, December 14, 2000.
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: M14KB4863
- Expiration date of the lot/batch: 2017-11-10 (retest date)
- Purity test date: 2015-05-12

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: At room temperature
- Stability under test conditions: The test samples were stored in the freezer (≤ -15°C). Storage stability of samples under these conditions was demonstrated in project 509941.
Analytical monitoring:
yes
Details on sampling:
- Sampling method: samples for possible analysis were taken form all test concentrations and the control at t=0 and t=48h. 2.0 mL of volume was taken from the approximate centre of the test vessels. At the end of the exposure period, the replicates were pooled at each concentration before sampling
- Sample storage conditions before analysis: the samples were stored in a freezer. Additionally, reserve samples of 2.0 mL were taken for possible analysis
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Due to expected low water solubility of the test substance a saturated solution (SS) was prepared. The preparation of test solutions started with a loading rate of 100 mg/L applying two days of stirring at room temperature in the dark to ensure maximal dissolution of the test item in the tes medium. The resulting aqueous mixture was filtered through a 0.45 µm membrane filter (RC55, Whatman) to remove any non-dissolved material. The filter was pre-conditioned with a small volume of test solution that was discarded to avoid loss of the test item due to adsorption on the filter. The resulting SS was used as the highest test concentration. The lower concentrations were prepared by subsequent dilutions in test medium.
- Evidence of undissolved material (e.g. precipitate, surface film, etc): final test solutions were clear and colourless
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Water-flea
- Source: in-house laboratory culture with a known history
- Age at study initiation (mean and range, SD): <24h (from parental daphnids of more than 2 weeks old)
- Method of breeding: 250 newborn daphnids (i.e. less than 3 days old) are placed into 5 litres of medium in an all-glass culture vessel. Medium is M7. After 7 days of cultivation half of the medium is renewed twice a week.
- Feeding during test: no

ACCLIMATION
- Acclimation period: max. 4 weeks
- Acclimation conditions (same as test or not): yes
- Type and amount of food: fresh water algae.
- Feeding frequency: daily
- Health during acclimation (any mortality observed): no
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Hardness:
180 mg/L as CaCO3
Test temperature:
19-20°C
pH:
At t= 0h: 7.7
At t= 48h: 8.1
Dissolved oxygen:
At t= 0h: 9.2-9.8 mg/L
At t= 48h: 9.1 mg/L
Salinity:
not relevant
Nominal and measured concentrations:
Final test =
Nominal concentrations: 1.0, 10 and 100% of a SS
Nominal concentration tested: 100 mg/L
Measured concentrations at t=0h: < 4 µg/L
Measured concentrations at t=48h: < 4 µg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: beaker
- Material, size, headspace, fill volume: 100 mL, glass beaker filled with 80mL
- Aeration: not during the test
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

OTHER TEST CONDITIONS
- Photoperiod: 16h light daily

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Immobility was defined as those organisms which are not able to swim within 15 seconds after gentle agitation of the test container and was monitored after 24 and 48 hours of continuous treatment with the test substance.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: x10
- Range finding study: combined/range finding study was performed
- Test concentrations: 1.0, 10 and 100% of a SS prepared at a loading rate of 100 mg/L
- Results used to determine the conditions for the definitive study: yes
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 100% v/v saturated solution, equivalent to a loading rate of 100 mg/L
Details on results:
- mortality of control: none
- Other adverse effects control: no
- Abnormal responses: none
Results with reference substance (positive control):
- Results with reference substance valid? yes (should lie between 0.3 and 1.0 mg/L)
- Mortality:
- EC50/LC50: 48-h EC50 = 0.38 mg/L with a 95% confidence interval between 0.33 and 0.43 mg/L. The sensitivity of the daphnia was within the range determined with the historical data collected at WIL Research Europe.
Reported statistics and error estimates:
No EC50 could be calculated because the test item proved to be non-toxic (EC50 > maximum soluble concentration tested)
Validity criteria fulfilled:
yes
Conclusions:
The acute toxicity of T003063 to Daphnia magna was determined in a 48-hour static test according to the OECD guideline 202.
No immobility was observed during the test period of 48 hours in the control and up to and including the highest saturated test concentration of 100 mg/L. At this nominal loading rate of 100 mg/L, no quantifiable amounts of test item were present in the test medium from the start of testing (i.e. actual test concentration was below the lowest calibration solution of 4 µg/L). The 48 hour EC50 for T003063 could not be quantified due to the absence of toxicity up to the highest concentration tested, and was clearly higher than 100 mg/L (nominal loading rate).

Description of key information

The study of Bouwman (2016), investigating the acute toxicity of T003063 in Daphnia magna according to OECD guideline 202, was considered as the key study for endpoint coverage.

No immobility was observed during the test period of 48 hours in the control and up to and including the highest saturated test concentration of 100 mg/L. At this nominal loading rate of 100 mg/L, no quantifiable amounts of test item were present in the test medium from the start of testing (i.e. actual test concentration was below the lowest calibration solution of 4 µg/L). The 48 hour EC50 for T003063 could not be quantified due to the absence of toxicity up to the highest concentration tested, and was clearly higher than 100 mg/L (nominal loading rate).

Key value for chemical safety assessment

Additional information