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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:
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)
Version / remarks:
Adopted April 13, 2004.
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
Samples for possible analysis were taken from all test concentrations and the control according to the schedule below.
- Frequency: at t=0 h and t=48 h
- Sampling method: 3.6 mL from the approximate centre of the test vessels
- Sample storage conditions before analysis: Samples were stored in a freezer (≤-15°C) until analysis at the analytical laboratory of the Test Facility.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
The batch of CH02906 tested was a white to brownish powder with a purity of 99.9% and completely soluble in test medium at the concentrations tested. No correction was made for the purity/composition of the test item.
Preparation of test solutions started with a concentration of 100 mg/L for the combined limit/range-finding test and 10 mg/L for the final test applying a stirring period of approximately 10 minutes to accelerate dissolution of the test item in medium. Lower test concentrations were prepared by subsequent dilutions of the 100 or the 10 mg/L concentration in test medium. All test solutions were clear and colorless at the end of the preparation procedure.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Source: In-house laboratory culture with a known history.
- Age of parental stock (mean and range, SD): Daphnids originated from a healthy stock, 2nd to 5th brood, showing no signs of stress such as mortality >20%, presence of males, ephippia or discoloured animals and there was no delay in the production of the first brood.
- Feeding during test: no
- Temperature of medium: 18-22°C
- Feeding: Daily, a suspension of fresh water algae.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Test temperature:
8-22°C, constant within 2°C
pH:
7.7-8
Dissolved oxygen:
8.9-9 mg/L
Nominal and measured concentrations:
1.0, 1.8, 3.2, 5.6 and 10 mg/L.
Samples taken from the two highest test concentrations were analysed and showed that the measured concentrations were in agreement with nominal at the start of the test (92%) and remained stable during the test period (95-96% of nominal at the end of the test period). Therefore, the EC50 values were based on the nominal test concentrations. No color changes of test solutions were observed during the test period.
Details on test conditions:
TEST SYSTEM
- Test vessel: 60 mL, all-glass
- Aeration: no
- No. of organisms per vessel: 5 per vessel containing 50 mL if test solution
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- No. of vessels per vehicle control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
M7, as prescribed by Dr. Elendt-Schneider (Elendt, B.-P., 1990: Selenium deficiency in Crustacea. An ultrastructural approach to antennal damage in Daphnia magna Straus. Protoplasma 154, 25-33).

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 hours

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Immobility (including mortality) at 24 hours and at 48 hours.


RANGE-FINDING STUDY
The study started with a combined limit/range-finding test. Twenty daphnids per concentration (four replicates, five daphnids per replicate) were exposed to a control and a concentration of 100 mg/L. Test procedure and conditions were similar to those applied in the final test with the following exceptions:
* Ten daphnids per concentration (two replicates, five daphnids per replicate) were exposed to 0.10, 1.0 and 10 mg/L;
* Dissolved oxygen concentrations and pH were only measured in the control and the highest test concentration.
Reference substance (positive control):
yes
Remarks:
K2Cr2O7 (June 2017)
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
10 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
8.4 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
At 10 mg/L, 45% immobility was observed after 24 hours of exposure and 80% immobility after 48 hours. No immobility was observed at or below 5.6 mg/L during the test period. Since no immobility or other effects were observed in the control this test was considered valid.
Results with reference substance (positive control):
The 24h-EC50 was 0.95 mg/L with a 95% confidence interval between 0.85 and 1.1 mg/L.
The 48h-EC50 was 0.59 mg/L with a 95% confidence interval between 0.52 and 0.66 mg/L.
Reported statistics and error estimates:
effect parameters based on analytically confirmed nominal concentrations:
24h EC50 (95% confidence interval) : 10 (9.0 - 12) mg/L
48h EC50 (95% confidence interval) : 8.4 (7.6 - 9.3) mg/L
Validity criteria fulfilled:
yes
Conclusions:
The 48h-EC50 for Daphnia magna exposed to CH02906 was 8.4 mg/L based on analytically confirmed nominal exposure concentrations (95% confidence interval between 7.6 and 9.3 mg/L).
Executive summary:

The objectiveof the study was to evaluate CH02906 for its ability to induce acute toxic effects on the mobility of Daphnia magna during an exposure period of 48 hours and, if possible, to determine the EC50at 24 and 48 hours of exposure.

The study procedures described in this report were based on the OECD guideline No. 202 (2004).

The batch of CH02906 tested was a white to brownish powder with a purity of 99.9% and completely soluble in test medium at the concentrations tested.

A final test was performed based on the results of a preceding combined limit/range-finding test. Twenty daphnids per group (four replicates, five daphnids per replicate) were exposed to a control and to nominal CH02906 concentrations of 1.0, 1.8, 3.2, 5.6 and 10 mg/L. The total exposure period was 48 hours and samples for analytical confirmation of exposure concentrations were taken at the start and at the end of the test.
 

Samples taken from the two highest test concentrations were analysed and showed that the measured concentrations were in agreement with nominal at the start of the test (92%) and remained stable during the test period (95-96% of nominal at the end of the test period). Therefore, the EC50values were based on the nominal test concentrations.

The study met the acceptability criteria prescribed by the study plan and was considered valid.

In conclusion, the 48h-EC50for Daphnia magna exposed to CH02906 was 8.4 mg/L (95% confidence interval between 7.6 and 9.3 mg/L) based on analytically confirmed nominal exposure concentrations.

Description of key information

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
8.4 mg/L

Additional information