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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:
11 May 2020 to 13 May 2020
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Study undertaken to GLP certification, based on OECD guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
Principles of method if other than guideline:
Guideline study
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch number of test material: RM1007030 RL750/18
- Expiration date of the lot/batch: 24/10/2020
- Purity test date: No data

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Closed vessel at room temperature (17.3 – 23.0 °C).
- Stability under storage conditions: No data
- Stability under test conditions:
- Solubility and stability of the test substance in the solvent/dispersant/vehicle/test medium: Solubility H2O: < 0.1 g/L; EtOH: > 1 g/L; acetone: > 1 g/L; CH3CN: > 1 g/L; DMSO: unknown; Stability: H2O: unknown; EtOH: 96h; acetone: 96h; CH3CN: 96h; DMSO: unknown
- Reactivity of the test substance with the solvent/vehicle /test medium (if applicable): No dat

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing:
- Preliminary purification step (if any): No data
- Preparation of a nanomaterial dispersion (incl. dilution): No data
- Final dilution of a dissolved solid, stock liquid or gel: No data
- Final preparation of a solid: No data

OTHER SPECIFICS
- measurement of pH, osmolality, and precipitate in the culture medium to which the test chemical is added: No data
- other information: No data
Analytical monitoring:
yes
Details on sampling:
- Concentrations:
Nominal concentrations were 4.6, 10, 22, 46, 100 mg/L
Geometric mean measured concentrations were 3.16, 7.73, 18.71, 40.66, 90.04 mg/L

- Sampling method: concentration and stability of the test item was verified by chemical analysis at 0, 24 hours (old media), 24 hours (old media) and 48 hours .Before each measurement of the samples were diluted using the calibration solvent acetonitrile/water 50/50 (% v/v) to stay in the calibrated range.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
Following OECD (2019)Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures, stock solutions containing 100 mg/L test item in dilution water were prepared. For this, the loading rate of 106.4 µL/L (based on a density of 0.94 g/mL, stated in the SDS) was mixed with dilution water. These solu-tions were treated with an ultrasonic bath for 30 minutes in order to achieve complete dissolution of the test item. The lower treatments (46 / 22 / 10 / 4.6 mg/L) were prepared by dilution of this stock solution with dilution water.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM

Daphnia magna is bred in the test facility throughout the year. The animals are kept for the use in toxicity tests. They multiply by parthenogenesis, thus being genetically identical. The keeping is performed similar to the method described in the OECD guideline, following SOP 115 002 01 („Zucht und Hälterung von Daphnia magna STRAUS“), version 13 from 11. Nov. 2019.

- Common name: Water flea
- Strain/clone: Berlin
- Age at study initiation (mean and range, SD): between 0 and 24 hours
- Vessels: preserving glasses, nominal volume 2 L
- Medium: M4-Medium (recipe of ELENDT)
- Food type: green algae (Desmodesmus subspicatus)
- Medium renewal: twice a week
- Photo period: 16/8 hours, using neon tubes
- Temperature: 20 (+/- 2 °C)

22.5 hours before the start of the test, the adult animals were separated from the young. 0.5 hours before test start, the adults were caught with the help of a glass tube, and the newborn daphnia (age < 24h) were sieved from the medium and immediately placed into a beaker containing dilution water. After the settling-in period, animals which showed no apparent damage were used for the test.

Using a glass tube, the daphnia were caught and lifted from the beaker. They were put on a small sieve, and the medium surrounding the animals was sucked off using absorbent paper. Immediately after that, the animals were put into the respective test solution.

Test type:
semi-static
Water media type:
freshwater
Remarks:
M4 medium (Elendt)
Limit test:
no
Total exposure duration:
48 h
Remarks on exposure duration:
None
Post exposure observation period:
None
Hardness:
No data (M4 Medium Elendt)
Test temperature:
19.4 – 21.2 °C
pH:
7.6 - 7.7
Dissolved oxygen:
8.6 - 9.1 mg/L
Salinity:
Not applicable
Conductivity:
No data (M4 Medium Elendt)
Nominal and measured concentrations:
Nominal concentrations were 4.6, 10, 22, 46, 100 mg/L
Geometric mean measured concentrations were 3.16, 7.73, 18.71, 40.66, 90.04 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Beakers, glass, nominal volume 50 mL containing 20 ± 5 mL test solution
- Renewal rate of test solution (frequency/flow rate): After 24 hours
- No. of organisms per vessel: Five
- No. of vessels per concentration (replicates): Four
- No. of vessels per control (replicates): Four

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: M4 medium (Elendt)

OTHER TEST CONDITIONS
- Photoperiod: 16/8 hours, using neon tubes

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : The test vessels were left to stand for 24 hours. Then immobilised daphnia were counted and a medium renewal was performed. The daphnia were put into new test vessels with freshly prepared test solution. After 48 hours, the immobilised daphnia were counted again. Daphnia are considered immobilised if they perform no movements or are only able to move their antennae when the beaker is gently agitated.

RANGE-FINDING STUDY
The concentrations to be tested are based on the result of a non-GLP pre-test.
Reference substance (positive control):
yes
Remarks:
Potassium dichromate (CAS No. 7778-50-9)
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
11.77 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
11.77 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
LOEC
Effect conc.:
18.71 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
7.73 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
The 3 highest concentrations showed 100% immobilization. The concentration-response curve was ex-tremely steep, showing a 0 to 100 % rise in immobilisation between two successive treatments. No im-mobilisation occurred in the control.
Results with reference substance (positive control):
Potassium dichromate K2Cr2O7 (CAS No. 7778-50-9) was used as positive control in a current reference study (202005R201). The 24h-EC50 value was determined as 2.01 mg/L. The value was within the request-ed range for the 24h-EC50 between 0.6 - 2.1 mg/L of potassium dichromate K2Cr2O7 as specified in the OECD guideline.
Reported statistics and error estimates:
Analysis of the immobilization data was carried out using the Weibull analysis using linear maximum-likelihood regression at 24 and 48 hours. All statistical analysis was carried out using the ToxRat Professional computer software package.

Parameter

Value

95%-confidence interval

24h EC50

11.77 mg/L

n. d.

48h EC50

11.77 mg/L

n. d.

48h NOEC

7.73 mg/L

--

48h LOEC

18.71 mg/L

--

Validity criteria fulfilled:
yes
Conclusions:
The reliable (K1) OECD 202 Guideline study found that acute toxicity was observed in Daphnia magna resulting in a 48-hr EC50 of 11.77 mg/l. based on measured geometric mean.
Executive summary:

The reliable (K1) OECD 202 Guideline study was performed to GLP standards and met validity criteria. The study was performed using five test concentrations ranging from 4.6 to 100 mg/L nominal concentration. For each test concentration and the blank control, 20 Daphnia were exposed to the test item for 48 hours in a semi static test system. After 24 and 48 hours, the immobilised Daphnia were counted.The three highest concentrations showed 100% immobilisation. None of the animals was immobilised in the blank control. At the test start, end and at medium renewal after 24 hours, the content of the test item in the test solutions was determined using HPLC. The measured concentrations were between 61 % and 99 % of the nominal concentration. Therefore, the determination of the results was based on the geometric mean of the measured concentrations (see § 23 OECD 202).


 


Acute toxicity (immobilisation) was observed in Daphnia magna resulting in a 48-hr EC50 of 11.77 mg/l. Other endpoint results are as follows:


 


48h-NOEC = 7.73 mg/L
48h-LOEC = 18.71 mg/L
24h-EC50= 11.77 mg/L
48h-EC50= 11.77 mg/L

Description of key information

The 48-h EC50 was 11.77 mg/L based on mobility for D. magna (Muckle, 2020)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
11.77 mg/L

Additional information