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Short-term toxicity to aquatic invertebrates

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Administrative data

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
12 Jan 2018 - 22 Jan 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report Date:
2018

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
2004
Deviations:
no
Qualifier:
according to
Guideline:
other: Guidance document on aquatic toxicity testing of difficult substances and mixtures, OECD series on testing and assessment number 23
Version / remarks:
2000
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
Appearance: Off-white powder
Test item storage: At room temperature

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
- Concentrations: Control and all test concentrations.
- Sampling method: 2.0 mL from the approximate centre of the test vessels, at t=0 h and t=48 h.
- Sample storage conditions before analysis: Samples were stored in a freezer (≤-15°C) until analysis at the analytical laboratory of the Test Facility.
- At the end of the exposure period, the replicates were pooled at each concentration before sampling.

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Preparation of test solutions started with a loading rate of 100 mg/L applying a three-day period of magnetic stirring to ensure maximum dissolution of the test item in medium. Thereafter, the aqueous Saturated Solution (SS) was collected by filtration through a 0.45 µm membrane filter (RC55, Whatman) and used as the highest test concentration. Lower test concentrations were prepared by subsequent dilutions of the SS in test medium. All test solutions were clear and colorless at the end of the preparation procedure.
- Controls: Test medium without test item or other additives.

Test organisms

Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Strain/clone: Straus 1820
- Source: In-house laboratory culture with a known history
- Age of parental stock: >2 weeks
- Age at test initiation: <24 h
- Feeding during test: no feeding
- Validity of batch: 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.

BREEDING
- Start of each batch: With newborn daphnids, i.e. less than 3 days old, by placing about 250 of them into 5 litres of M7 medium in an all-glass culture vessel.
- Maximum age of the cultures: 4 weeks
- Renewal of the cultures: After 7 days of cultivation half of the medium twice a week.
- Temperature of medium: 18-22°C
- Feeding: Daily, a suspension of fresh water algae.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h

Test conditions

Hardness:
180 mg/L (as CaCO3)
Test temperature:
20 - 21 °C
pH:
At t=0 h: 7.8 - 7.9 (n=4)
At t=48 h: 8.3 - 8.4 (n=2)
Dissolved oxygen:
At t=0 h: 9.1 - 9.3 mg/L (n=4)
At t=48 h: 8.7 - 8.8 mg/L (n=4)
Nominal and measured concentrations:
Nominal: 1.0, 10, 100% of saturated solution prepared at 100 mg/L
Measured: 100% of SS: 1.95 mg/L (stable throughout the test duration). Effect parameters were based on initially measured concentrations
Details on test conditions:
TEST SYSTEM
- Test vessel: 60 mL, all-glass, containing 50 mL of test solution
- Aeration: no aeration
- No. of organisms per vessel: 5 daphnids
- No. of vessels per concentration (replicates): 4 for undiluted SS, 2 for 1.0 and 10% of SS.
- No. of vessels per control (replicates): 4
- Introduction of daphnids: 20 minutes after preparation of the test solutions.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Adjusted ISO medium, prepared with tap water purified by Reverse Osmosis.
- Culture medium different from test medium: Yes
- Intervals of water quality measurement: pH and dissolved oxygen: at the start of the test for all test concentrations and the control; at the end of the test for only the undiluted SS and control. Temperature of medium: continuously in a temperature control vessel, beginning at the start of the test.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 h photoperiod daily

EFFECT PARAMETERS MEASURED
- Immobility (including mortality): at 24 h and at 48 h
Reference substance (positive control):
yes
Remarks:
Potassium dichromate (performed Jan 2018)

Results and discussion

Effect concentrations
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 2 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
mobility
Remarks on result:
other: Measured concentration is considered the maximum soluble concentration of test item in test medium at a loading rate of 100 mg/L
Details on results:
- No immobility was observed in the control or any of the test concentrations throughout the test.
- Water quality parameters remained within the limits as laid down in the Study Plan.
Results with reference substance (positive control):
- Results with reference substance valid? Yes
- The 24h-EC50 was 0.87 mg/L (95% confidence interval 0.80 - 0.95 mg/L)
- The 48h-EC50 was 0.54 mg/L (95% confidence interval 0.49 - 0.61 mg/L)
- Actual responses in this reference test are within the ranges of the expected responses at the different concentrations, i.e. the 48h-EC50 was between 0.3 and 1.0 mg/L. Hence, the sensitivity of this batch of D. magna was in agreement with the historical data collected at the Test Facility.

Any other information on results incl. tables

Table 1: Number of Introduced Daphnids and Incidence of Immobility

Time (h)

Replicate

Test item; %SS prep. at 100 mg/L

Control

1.0

10

100

0

A

5

5

5

5

B

5

5

5

5

C

5

 

 

5

D

5

 

 

5

Total introduced

20

10

10

20

24

A

0

0

0

0

B

0

0

0

0

C

0 (1)

 

 

0

D

0

 

 

0

Total immobilised

0

0

0

0

Effect %

0

0

0

0

 

 

 

 

48

A

0

0

0

0

B

0

0

0

0

C

0

 

 

0

D

0

 

 

0

Total immobilised

0

0

0

0

Effect %

0

0

0

0

( ) - Number of daphnids observed trapped at the surface of the test solutions. These organisms were reimmersed into the respective solutions before recording of mobility.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
See 'Overall remarks' for details on validity criteria
Conclusions:
The 48h-EC50 for Daphnia magna was beyond the range tested, i.e. exceeded a measured concentration of 2.0 mg/L being considered the maximum soluble concentration of the test item in test medium at a loading rate of 100 mg/L.
Executive summary:

In a 48 h acute toxicity test conducted according to OECD guideline 202, Daphnia magna were exposed to an untreated control 1.0, 10 and 100% of saturated solutions of the test item prepared at a loading rate of 100 mg/L (5 daphnids per vessel, 4 replicates for control and 100% of SS, 2 replicates for 1.0 and 10% of SS). Measured concentration in 100% of SS was 1.95 mg/L at start and end of the test. No immobility was observed in the control or any of the test concentrations throughout the test. The 48h-EC50 was >2.0 mg/L, being considered the maximum soluble concentration of the test item in test medium at a loading rate of 100 mg/L. The study met all validity criteria and is considered to be reliable without restrictions.