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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:
4th - 27th February, 2013
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
Qualifier:
according to
Guideline:
other: ISO International Standard 6341: "Water quality - Determination of the inhibition of the mobility of Daphnia magna Straus - Acute toxicity test (1996)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations sampled for analysis
Range-finding test: 10 mg/L
Final test: 0 (blank-control), 32, 56 and 100 mg/L
- Sampling
Frequency: at t=0 h and t=48 h
Volume: 2 ml

- Sample storage conditions before analysis: Samples were stored in a freezer until analysis (≤ -15°C). On the day of analysis, the samples were defrosted at room temperature. If necessary, the samples were diluted with ISO-medium to obtain concentrations within the calibration range.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The preparation of test solutions started with the highest test concentration. No special treatment other than a short magnetic stirring period was applied to fully dissolve the test substance in test medium. The lower test concentrations were prepared by subsequent dilutions in test medium.
- Controls: blank control (test medium without test substance or other additives)
- Evidence of undissolved material: The final test solutions were all clear and colourless.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Water flea
- Source: In-house laboratory culture with a known history (at least third generation, obtained by acyclical parthenogenesis under specified breeding conditions)
- Age at study initiation: <24 h
- Method of breeding: 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. Each batch was started with newborn daphnids, i.e. less than 3 days old. M7 medium (according to: Elendt, B.-P., 1990 Selenium deficiency in Crustacea. An ultrastructural approach to antennal damage in Daphnia magna Straus. Protoplasma 154, 25-33) was used. Maximum age of the cultures was 4 weeks.
- Type of food and feeding frequency during breeding: suspension of fresh water algae, feed daily.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
180 mg/L expressed as CaCO3
Test temperature:
- Final test:
At start temperature varied between 19.9 and 20.3°C
The temperature continuously measured during the test varied between 18.9 and 19.6°C
pH:
- Final test
At start: 7.9
At the end: 8.1
Dissolved oxygen:
- Final test (mg/L)
At start: 9.9
At the end: 9.2 - 9.3
Nominal and measured concentrations:
- Nominal
Range-finding test: 0 (blank-control), 0.1, 1, 10 and 100 mg/L
Final test: 0 (blank-control), 10, 18, 32, 56 and 100 mg/L

- Measured: See the "Remarks on results including figures and tables" field for details.
Details on test conditions:
TEST SYSTEM
- Test vessel: All-glass, with a capacity of 100 ml and filled with 80 ml of test solution
- Aeration: No
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates)
Range-finding test: 4 replicates for the 100 mg/L and 2 replicates for 0.1, 1.0 and 10 mg/L
Final test: 4 replicates
- No. of vessels per control (replicates):
Range-finding test: 4 replicates
Final test: 4 replicates

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: tap water purified by Reverse Osmosis
- Breeding medium: M7
- Test medium: Adjusted ISO medium
- Intervals of water quality measurement
Range-finding test: Dissolved oxygen concentrations and pH were only measured in the control and the highest test concentration

Final test:
pH and dissolved oxygen - At the beginning and at the end of the test, for all concentrations and the control.
Temperature of medium - Continuously in a temperature control vessel, beginning at the start of the test.

OTHER TEST CONDITIONS
- Photoperiod: 16 h light : 8 h dark

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

TEST CONCENTRATIONS
- Spacing factor for test concentrations: approx. X1.8
- Range finding study
- Test concentrations: 0 (blank-control), 0.1, 1, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study: yes
Reference substance (positive control):
yes
Remarks:
potassium dichromate (K2Cr2O7)
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
48 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks:
(including mortality)
Remarks on result:
other: 95% CL: 27 to 75 mg/L
Details on results:
- Range-finding test: No immobility was observed at concentrations of 0.10, 1.0 and 10 mg/L. The immobility at the highest concentration was 90% after 48 hours. Therefore, the expected EC50 was between 10 and 100 mg/L.

- Final test: The responses recorded were in agreement with what was expected based on the results of the range-finding test. Accelerator (PT 25E or PT 25E/2) did not induce significant acute immobilisation of Daphnia magna at 32 mg/L after 48 hours of exposure (NOEC)
- Acceptability of the test:
1. In the control, no daphnids became immobilised.
2. The oxygen concentration at the end of the test was ≥ 3 mg/L in control and test vessels.
Results with reference substance (positive control):
Potassium dichromate (K2Cr2O7): The 48h-EC50 was 0.53 mg/L with a 95% confidence interval between 0.49 and 0.62 mg/L.

- Range-finding test

Measured concentrations:

Concentrations of the test substance in test medium in the range-finding test

Time of sampling
[hours]

Date of

sampling

Date of

analysis1

Concentration

Relative to nominal
[%]

Relative to initial
[%]

Nominal
[mg/L]

Analysed
[mg/L]

Analysed

corrected2
[mg/L]

 

 

 

 

 

 

 

 

0

04 -Feb-2013

11 -Feb-2013

10

11.4

10.0

100

 

 

 

 

 

 

 

 

 

48

06 -Feb-2013

11 -Feb-2013

10

11.4

10.1

101

100

 

 

 

 

 

 

 

 

1          Samples were stored in the freezer (≤ -15°C) until the day of analysis.

2          Corrected for the 113% mean recovery of all procedural recovery samples analysed in this series.

Biological results:

Incidence of immobility in the range-finding test

Concentration

Accelerator

(PT 25E or PT 25E/2)

(mg/L)

Vessel number

 

Number

Daphnia

exposed

Response at 24 h

Response at 48 h

 

number

Total

%

 

number

Total

%

Control

A

B

C

D

5

5

5

5

0

0

0

0

0

0

0

0

0

0

       0.1

A

B

5

5

0

0

0

0

0

0

       1.0

A

B

5

5

0

0

0

0

0

0

     10

A

B

5

5

0

0

0

0

0

0

   100

A

B

C

D

5

5

5

5

3

2

1

1

35

5

4

5

4

90

- Final test

Measured concentrations:

Concentrations of the test substance in test medium - final test

Time of sampling
[hours]

Date of

sampling

Date of

analysis1

Concentration

Relative to nominal
[%]

Relative to initial
[%]

Nominal
[mg/L]

Analysed
[mg/L]

Analysed

corrected2
[mg/L]

 

 

 

 

 

 

 

 

0

25 -Feb-2013

04 -Mar-2013

0

n.d.

n.d.

n.a.

 

 

 

 

32

37.4

33.6

105

 

 

 

 

56

64.8

58.3

104

 

 

 

 

100

116

104

104

 

 

 

 

 

 

 

 

 

48

27 -Feb-2013

04 -Mar-2013

0

n.d.

n.d.

n.a.

 

 

 

 

32

37.4

33.6

105

100

 

 

 

56

64.7

58.2

104

100

 

 

 

100

116

104

104

100

 

 

 

 

 

 

 

 

1          Samples were stored in the freezer (≤ -15°C) until the day of analysis.

2          Corrected for the 111% mean recovery of the 100 mg/l procedural recovery samples analysed in this series.

n.d.    Not detected.

n.a.     Not applicable.

Biological results:

Acute immobilisation of daphnids after 24 and 48 hours in the final test

Concentration

Accelerator

(PT 25E or PT 25E/2)

(mg/L)

Vessel

number

 

Number

Daphnia

exposed

Response at 24 h

Response at 48 h

 

number

Total

%

 

number

Total

%

Control

 A

 B

C

D

5

5

5

5

0

0

0

0

0

0

0 (2)

0

0

0

10

 A

 B

C

D

5

5

5

5

0

0

0

0

0

0

0

0

0

0

18

 A

 B

C

D

5

5

5

5

0

0

0

0

0

0

0

0

0

0

32

 A

 B

C

D

5

5

5

5

0

0

1

0 (1)

5

0

0

1

0

5

56

 A

 B

C

D

5

5

5

5

1

1

1

4

35

4

5

4

5

90

100

 A

 B

C

D

5

5

5

5

1

1

1

3

30

5

3

5

4

85

( ) between brackets: number of daphnia observed trapped at the surface of the test solutions. These organisms were reimmersed into the respective solutions before recording of mobility.

Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of the present study Accelerator (PT 25E or PT 25E/2) did not induce significant acute immobilisation of Daphnia magna at 32 mg/L after 48 hours of exposure (NOEC). The 48h-EC50 was 48 mg/L based on analytically confirmed nominal exposure concentrations (95% confidence interval between 27 and 75 mg/L).
Executive summary:

In a 48-h acute toxicity study conducted according to OECD guideline 202, water fleas (Daphia magna) were exposed to Accelerator (PT 25E or PT 25E/2) under static conditions at the following nominal concentrations: 0 (blank-control), 10, 18, 32, 56 and 100 mg/L. Accelerator (PT 25E or PT 25E/2) did not induce significant acute immobilisation of Daphnia magna at 32 mg/L after 48 hours of exposure. The 48h-EC50 was 48 mg/L based on analytically confirmed nominal exposure concentrations (95% confidence interval between 27 and 75 mg/L). The study is considered to be reliable without restrictions.

Description of key information

In a 48-h acute toxicity study conducted according to OECD guideline 202, water fleas (Daphia magna) were

exposed to Accelerator (PT 25E or PT 25E/2). The 48h-EC50 was 48 mg/L based on analytically confirmed

nominal exposure concentrations. The study is considered to be reliable without restrictions.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
48 mg/L

Additional information

In a 48-h acute toxicity study conducted according to OECD guideline 202, water fleas (Daphia magna) were exposed to Accelerator (PT 25E or PT 25E/2) under static conditions at the following nominal concentrations: 0 (blank-control), 10, 18, 32, 56 and 100 mg/L. Accelerator (PT 25E or PT 25E/2) did not induce significant acute immobilisation of Daphnia magna at 32 mg/L after 48 hours of exposure. The 48h-EC50 was 48 mg/L based on analytically confirmed nominal exposure concentrations (95% confidence interval between 27 and 75 mg/L). The study is considered to be reliable without restrictions.