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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:
From August 22, 2017 to August 29, 2017
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
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
Batch No.: WD0066442; Purity: 100 % (UVCB); Appearance: amber, homogeneous liquid
Analytical monitoring:
yes
Details on sampling:
23 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, aged between 0 and 22 hours, were sieved from the medium and immediately placed into a 250 mL-beaker containing dilution water. After a settling-in period of 30 minutes, 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.
Vehicle:
no
Details on test solutions:
In a non-GLP pre-test, the pH of a test solution with the loading rate 10 g/L was determined as pH 3.4. Therefore, the study was performed with pH adjustment. For this 2 M HCl was used. The water-accommodated fraction was prepared for the test. This was done by weighing the nominal loads, adding the corresponding amount of dilution water and shaking vigorously for 24 hours. The resulting solutions were filtrated through 0.45 μm PTFE filters.

Nominal concentration in g/L, Real load in g/L
0.46 0.462
1.0 1.004
2.2 2.206
4.6 4.615
10 10.007
Test organisms (species):
Daphnia magna
Details on test organisms:
Specification: Species Daphnia magna; Variety: STRAUS; Strain: Berlin; Sex: female; Age: between 0 and 24 hours; Origin: Umweltbundesamt Berlin; In-house breeding since 27. September 2007.
Animal Husbandry: Daphnia magna is bred in the LAUS GmbH 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, following SOP 115 002 01 („Zucht und Hälterung von Daphnia magna STRAUS“), Version: 12 from 02. Feb. 2015.
Test type:
static
Water media type:
other: dilution water
Limit test:
no
Total exposure duration:
48 h
Hardness:
Resulting hardness in mmol/L: 2.502 mg/L
Resulting hardness in mg CaCO3/L: 250 mg/L
Test temperature:
20.5 – 22.7 °C
pH:
In the treatments 1.0 / 2.2 / 4.6 / 10 g/L the pH was adjusted with 2 M HCl. The pH range after adjustment: 6.6 - 7.8
Dissolved oxygen:
not specified
Salinity:
not specified
Conductivity:
not specified
Nominal and measured concentrations:
Nominal contentrations: 0.46 / 1.0 / 2.2 / 4.6 / 10 g/L
Geometric mean of measured concentrations: 20, 38, 62, 120, 266 mg/L
Details on test conditions:
Test vessels: glass beakers, nominal volume 50 mL, tall shape
Replicates (Treatments): 4 vessels, each containing 20 ± 5 mL test solution and 5 Daphnia
Replicates (Blank control): 4 vessels, each containing 20± 5 mL dilution water and 5 Daphnia
Reference substance (positive control):
yes
Remarks:
Potassium dichromate K2Cr2O7
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
266 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
62 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
10 g/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
2.2 g/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
mobility
Details on results:
The two highest concentrated treatments showed significant toxicity (10 and 40 % immobilisation). In the control and the lower concentrated treatments none of
the daphnids were immobilized.
Results with reference substance (positive control):
Potassium dichromate K2Cr2O7 (CAS No. 7778-50-9) was used as positive control. The 24h-EC50 value was determined as 1.6 mg/L.

VALIDITY:

- Immobilisation in the controls may not exceed 10 %,

- Immobilisation in the controls was 0 %,

- The concentration of dissolved oxygen at the end of the test must be at least 3 mg/L. The lowest concentration of dissolved oxygen at the end of the test was at least 8.1 mg/L.

Validity criteria fulfilled:
yes
Conclusions:
Under the study conditions, the following results were determined for the test substance (mean measured concentrations): 48 h NOEC: 62 mg/L and 48 h EC50: >266 mg/L (limit of solubility). This corresponds to the following nominal concentrations: 48 h NOEC: 2.2 g/L and 48 h EC50 >10 g/L (limit of solubility).
Executive summary:

A study was conducted to determine toxicity of the test substance towards Daphnia magna according to OECD Guideline 202 and EU Method C.2, in compliance with GLP. The study was performed using 5 concentrations ranging from 0.46 to 10 g/L (nominal loading rates), prepared as Water Accommodated Fractions (WAF). Twenty Daphnia were exposed to each concentration for 48 h in a static system. After 24 and 48 h, the immobilised Daphnia were counted. At the beginning and at the end of the test, test substance concentrations were monitored by Dissolved Organic Carbon (DOC) determination. The negative and positive controls met the validity criteria. The two highest test substance concentrations showed significant toxicity (10 and 40% immobilisation, respectively). The correlation between nominal and measured concentration was weak because of the limited solubility of the test substance. Therefore, the geometric mean of the measured concentrations was used for the determination of the results. Under the study conditions, the following results were determined for the test substance (mean measured concentrations): 48 h NOEC: 62 mg/L and 48 h EC50: >266 mg/L (limit of solubility). This corresponds to the following nominal concentrations: 48 h NOEC: 2.2 g/L and 48 h EC50 >10 g/L (limit of solubility) (Muckle, 2017).

Description of key information

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
266 mg/L

Additional information

A study was conducted to determine toxicity of the test substance towards Daphnia magna according to OECD Guideline 202 and EU Method C.2, in compliance with GLP. The study was performed using 5 concentrations ranging from 0.46 to 10 g/L (nominal loading rates), prepared as Water Accommodated Fractions (WAF). Twenty Daphnia were exposed to each concentration for 48 h in a static system. After 24 and 48 h, the immobilised Daphnia were counted. At the beginning and at the end of the test, test substance concentrations were monitored by Dissolved Organic Carbon (DOC) determination. The negative and positive controls met the validity criteria. The two highest test substance concentrations showed significant toxicity (10 and 40% immobilisation, respectively). The correlation between nominal and measured concentration was weak because of the limited solubility of the test substance. Therefore, the geometric mean of the measured concentrations was used for the determination of the results. Under the study conditions, the following results were determined for the test substance (mean measured concentrations): 48 h NOEC: 62 mg/L and 48 h EC50: >266 mg/L (limit of solubility). This corresponds to the following nominal concentrations: 48 h NOEC: 2.2 g/L and 48 h EC50 >10 g/L (limit of solubility) (Muckle, 2017).