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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:
2019-10-14 - 2019-10-18 (experimental phase)
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
under GLP
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
OECD Guideline for Testing of Chemicals No. 202, adopted 13. Apr. 2004:
”Daphnia sp., Acute Immobilisation Test“
Deviations:
yes
Remarks:
but not affecting the validity or integrity of the study
Qualifier:
according to guideline
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Version / remarks:
Commission Regulation (EC) No. 440/2008, Method C.2. “Daphnia sp. Acute Immobilisation Test”, adopted 30. May 2008
Deviations:
yes
Remarks:
but not affecting the validity or integrity of the study
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
The test item was stored in the test facility in a closed vessel in a fridge at 2.5 – 8.3 °C, away from light and humidity.
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 0, 4.6, 10, 22 mg/L, 46 mg/L and 100 mg/L (nominal)
- Miscellaneous: On each sampling day, validity of calibration was controlled by measuring QC samples (1 mg/L). Before the first measurement at the start of the test, a new calibration was performed.
Vehicle:
no
Remarks:
test medium was used
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A saturated solution was prepared for the test. This was done by weighing the real load of 100.4 mg/L, adding the corresponding amount of dilution water and shaking vigorously for 23.75 hours. The resulting solution was filtrated through 0.45 µm PTFE filters and the filtrate was used as test medium of the highest test concentration of nominal 100 mg/L. The lower treatments (4.6 / 10 / 22 / 46 mg/L nominal) were prepared by dilution of this filtrate with dilution water.
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): none
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: water flea
- Strain/clone: Daphnia magna STRAUS Berlin
- Source: Daphnia magna is bred in the laboratory throughout the year. The animals are kept for the use in toxicity tests. They multiply by parthenogenesis, thus being genetically identical. The husbandry is performed similar to the method described in the OECD guideline.
- Feeding during test: no
- Food type: green algae (Desmodesmus subspicatus)

METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES:
24 hours before the start of the test, the adult animals were separated from the young. 1 hour before test start, the adults were caught with the help of a glass tube, and the neo-nates (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.
Switching from M4-medium (husbandry) to Dilution water (test) has been shown not to cause any detrimental effects for test daphnia, therefore no acclimation period of 48 h was performed. This is a deviation from OECD Guideline No. 202 and EU-Method C.2, which can be considered uncritical.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
none
Test temperature:
19.4 – 20.3 °C
pH:
7.8
Dissolved oxygen:
8.1 - 9.0 mg/L O2
Nominal and measured concentrations:
- Nominal: 4.6 / 10 / 22 / 46 / 100 mg/L
- Measured, t = 0h: 1.20 / 2.51 / 5.19 / 13.17 / 26.69 mg/L
- Measured, t = 48h: 0.71 / 1.64 / 3.20 / 7.55 / 18.99 mg/L.

The concentrations determined at the start of the test ranged from 24 % to 29 % of the nominal concentration. At the end of the test the determined concentrations ranged from 15 % to 19 % of the nominal concentration. Therefore, the determination of the results was based on the geometric mean of the measured concentrations.
Details on test conditions:
TEST SYSTEM
- Test vessel: beakers
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: glass beakers, nominal volume 50 mL, tall shape, 20 ± 5 mL fill volume
- Aeration: The dilution water was aerated after preparation.
- Renewal rate of test solution (frequency/flow rate): no
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 5
- No. of vessels per vehicle control (replicates): n/a

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16/8 hours
- Light intensity: not stated, neon tubes

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : immobility after 24 and 48 hours, pH and O2 after 0 and 48 hours.

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 K2Cr2O7 (CAS No. 7778-50-9) was used as positive control in a current reference study.
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
4.98 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
3.01 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
2.03 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
LOEC
Effect conc.:
4.08 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Behavioural abnormalities: none
- Mortality of control: none
- Other adverse effects control: none
- Abnormal responses: none
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: none
Results with reference substance (positive control):
- Results with reference substance valid? yes
- Relevant effect levels: 24h EC50
- Limit test: no
- Dose-response test: yes
- ECx: The 24h-EC50 value was determined as 1.98 mg/L. The value was within the requested 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:
The estimation of the biological results was accomplished using the software ToxRat® Professional, version 3.3.0.
Validity criteria fulfilled:
yes
Conclusions:
- 48h-NOEC = 2.03 mg/L (geom. mean)
- 48h-LOEC = 4.08 mg/L (geom. mean)
- 24h-EC50 = 4.98 mg/L (geom. mean)
- 48h-EC50 = 3.01 mg/L (geom. mean)
Executive summary:

The study was conducted under GLP according to OECD Guideline 202 and EU Method C.2 on the registration substance itself. One valid experiment was performed using 5 concentrations ranging from 4.6 to 100 mg/L (nominal).

Due to the poor water solubility of 2-hydroxy-1-[4-(4-(2-hydroxy-2-methylpropionyl)phenoxy)phenyl]-2-methylpropan-1-one, a saturated solution was prepared as test medium of the highest test concentration by direct weighting, prolonged stirring and subsequent filtration according to OECD Guidance document No. 23. The lower treatments were prepared by dilution of this filtrate with dilution water.

For each test concentration and the blank control, 20 daphnia were exposed to the test item for 48 hours in a static test system. After 24 and 48 hours, the immobilised daphnia were counted.

Four concentrations showed toxicity between 5 and 100 % immobilisation. None of the animals was immobilised in the blank control.

Potassium dichromate K2Cr2O7(CAS No. 7778-50-9) was used as positive control in a current reference study to assure that the test conditions are reliable.

At the beginning and at the end of the test, the content of the test item in the test solutions was determined using HPLC-UV-determination. The concentrations determined at the start of the test ranged from 24 % to 29 % of the nominal concentration. At the end of the test the determined concentrations ranged from 15 % to 19 % of the nominal concentration. Therefore, the determination of the results was based on the geometric mean of the measured concentrations.

The following results were determined for the test item 2-hydroxy-1-[4-(4-(2-hydroxy-2-methylpropionyl)phenoxy)phenyl]-2-methylpropan-1-one (species: Daphnia magna).

 

- 48h-NOEC = 2.03 mg/L

- 48h-LOEC = 4.08 mg/L

- 24h-EC50= 4.98 mg/L

- 48h-EC50= 3.01 mg/L

 

Description of key information

Freshwater invertebrates Daphnia magna (OECD 202; GLP):

- 48h-NOEC = 2.03 mg/L (geom. mean)

- 48h-LOEC = 4.08 mg/L (geom. mean)

- 24h-EC50 = 4.98 mg/L (geom. mean)

- 48h-EC50 = 3.01 mg/L (geom. mean)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
3.01 mg/L

Additional information

A reliability score of 1 was assigned for the GLP guideline study, in accordance with the criteria for assigning data quality in line with the principles described by Klimisch (1997).