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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 04-Dec-2018 to 06-Dec-2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
2004
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Version / remarks:
2008
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
Sample preparation
Fivefold Enrichment (treatments 10 mg/L and 4.6 mg/L)
4 g NaCl were added to 50 mL of the test item solution in matrix; then, the clear solution was extracted two times with the solvent ethyl acetate (8 and 4 mL), the organic phase was collected into a 10 mL flask, after drying with Na2SO4. The flask was filled up to 10 mL with ethyl acetate after addition of 500 µL ISTD (internal standard) stock solution (1000 mg/L in ethyl acetate) and the solution was measured via GC/FID.
Tenfold Enrichment (treatment 2.2 mg/L, 1 mg/L and 0.46 mg/L)
6 g NaCl were added to 100 mL of the test item solution in matrix (or blank matrix Daphnia test medium); then, the clear solution was extracted two times with the solvent ethyl acetate (10 and 4 mL), the organic phase was collected into a 10 mL flask, after drying with Na2SO4. The flask was filled up to 10 mL with ethyl acetate after addition of 500 µL ISTD (internal standard) stock solution (1000 mg/L in ethyl acetate) and the solution was measured via GC/FID.

Miscellaneous
On each sampling day, validity of calibration was controlled by measuring QC samples.
At the measurement of 0 h, the deviation of the QC sample was higher than ± 3 % and lower than ± 15 %. Therefore, the recovery rate calculated from the QC samples was taken into account as sensitivity correction factor using the following equations:
QC Recovery in % = (measured concentration/nominal concentration)*100%

At the measurement of 48 h, the deviation of the QC sample was higher than ± 15 % and therefore a new calibration was performed without level 3 mg/L, because the recovery rate lay outside 100 ± 20 %.
The recovery rate calculated from the QC samples was taken into account at the measurement of 48 h using the equations above. The deviation of the mean of these samples was higher than ± 3 % and lower than ± 15 %.
Furthermore, the recovery rate of the medium was taken into account at each measurement.
Test organisms (species):
Daphnia magna
Details on test organisms:
Specification
Species Daphnia magna
Authority STRAUS
Strain Berlin
Sex female
Age between 0 and 24 hours
Origin Umweltbundesamt Berlin
In-house breeding since 27. September 2007
Selection of the test system was made following the proposal of the guidelines.

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“), in the current edition.
Vessels preserving glasses, nominal volume 2 L
Medium M4-Medium (recipe of ELENDT)
Food green algae (Desmodesmus subspicatus)
Medium renewal twice a week
Photo period 16/8 hours, using neon tubes
Temperature 20 ± 2 °C
Test type:
static
Water media type:
freshwater
Total exposure duration:
48 h
Hardness:
Resulting hardness in mmol/L: 2.502
Resulting hardness in mg CaCO3/L: 250
Test temperature:
20 ± 2 °C
pH:
7.8 - 8.6
Dissolved oxygen:
O2-Concentration in mg/L: 7.6-8.7
Nominal and measured concentrations:
The measured concentrations lay between 103 % and 121 % of the nominal concentra-tions at the beginning of the test and between 60 % and 77 % of the nominal concentra-tions at the end of the test. Therefore, the determination of the results was based on the geometric mean of the measured concentrations.
- Nominal concentrations: 0, 0.46, 1, 2.2, 4.6 and 10 mg/l.
- Measured (t =0 days): < LOQ (0.5 mg/l), 0.47, 1.03, 2.48, 5.18 and 12.08 mg/L
(t = 48 h) : < LOQ (0.5 mg/l), < LOQ (0.5 mg/l), 0.6, 1.35, 3.41 and 7.69 mg/L
Details on test conditions:
Test system
Test vessel: Closed glass flasks nominal volume 65 mL
Treatments: 4 vessels, each completely filled with test solution and 5 daphnia
Temperature: 19.6 – 21.3°C
- Observation times: 24 and 48 hours
- pH and O2-Concentration measurements: at the start and the end of
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:
48 h
Dose descriptor:
NOEC
Effect conc.:
1.83 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
2.2 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
LOEC
Effect conc.:
4.2 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
LOEC
Effect conc.:
4.6 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
4.12 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95%-CI not determinable due to mathematical reasons or inappropriate data
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
3.05 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95%-confidence interval: 2.51 mg/L – 3.64 mg/L
Details on results:
One valid experiment was performed.
The study was performed using 5 concentrations ranging from 0.46 to 10 mg/L. For each test concentration and the blank control, 20 Daphnia were exposed to the test item for 48 hours in a closed static test system. After 24 and 48 hours, the immobilised Daphnia were counted.
Three 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 solu-tions was determined using GC/FID-determination. The concentrations determined at the start of the test lay in a range of 103 to 121 % of the nominal concentration. At the end of the test the determined concentrations lay in a range of 60 to 77 % of the nominal con-centration. Therefore, the determination of the biological results was based on the geo-metric means of the measured concentrations.
No test item could be measured after 48 h and no immobilisation occurred at the lowest tested concentration. Therefore, this concentration was not used for the evaluation of the biological results.
No observations were made which might cause doubts concerning the validity of the study outcome. All validity criteria were met.
The result of the test is considered valid.
Results with reference substance (positive control):
Potassium dichromate K2Cr2O7 (CAS No. 7778-50-9) was used as positive control in a current reference study (201714R201). The 24h-EC50 value was determined as 1.9 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.

No observations were made which might cause doubts concerning the validity of the study outcome.

All validity criteria were met.

The result of the test is considered valid.

Validity criteria fulfilled:
yes
Conclusions:
48h-EC50 daphnina magna = 3.05 mg/L (nominal)
Executive summary:

One valid experiment was performed.

The study was performed using 5 concentrations ranging from 0.46 to 10 mg/L (nominal). For each test concentration and the blank control, 20 Daphnia were exposed to the test item for 48 hours in a closed static test system. After 24 and 48 hours, the immobilised Daphnia were counted.

The three highest concentrations showed toxicity between 5 and 100% immobilisation after 48 h of exposure. None of the animals was immobilised in the blank control.

Potassium dichromate K2Cr2O7(CAS No. 7778-50-9) was used as positive controlin 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 usingGC/FID-determination.

The measured concentrations lay between 103 % and 121 % of the nominal concentrations at the beginning of the test and between 60 % and 77 % of the nominal concentrations at the end of the test. Therefore, the determination of the results was based on the geometric mean of the measured concentrations.

No test item could be measured after 48 h and no immobilisation occurred at the lowest tested concentration. Therefore, this concentration was not used for the evaluation of the biological results.

The following results were determined for the test item Naphthalene-1,5-diol (species:Daphnia magna).

 

48h-NOEC = 1.83 mg/L, geom. mean (nominal 2.2 mg/L)
48h-LOEC = 4.20 mg/L, geom. mean (nominal 4.6 mg/L)
24h-EC50= 4.12 mg/L
48h-EC50= 3.05 mg/L


Description of key information

One valid experiment was performed.

The following results were determined for the test item Naphthalene-1,5-diol (species:Daphnia magna).

 

48h-NOEC = 1.83 mg/L, geom. mean (nominal 2.2 mg/L)
48h-LOEC = 4.20 mg/L, geom. mean (nominal 4.6 mg/L)
24h-EC50= 4.12 mg/L
48h-EC50= 3.05 mg/L

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
3.05 mg/L

Additional information