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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:
29 Jun - 10 Sep 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:
2004
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
Swiss Federal Office of Public Health, Consumer protection directorate, Notification authority for chemicals, Bern, Switzerland
Analytical monitoring:
yes
Details on sampling:
- Concentrations: The control and loading rates of 50 and 100 mg/L were analysed analytically. The lower loading rates of 6.25, 12.5 and 25 mg/L were not analysed since they were not relevant for the interpretation of the biological results.
- Sampling method: Duplicate samples were taken from each loading rate and the control at the start and end of the test. For sampling from the aged test media, the contents of the respective replicates were combined prior to sampling.
- Sample storage conditions before analysis: All samples were stored frozen (at -20 ± 5 °C) immediately after sampling.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Water Accommodated Fractions (WAFs) were prepared individually. The test item was mixed into test water by intensive stirring for 96 h in a closed vessel in the dark to dissolve the different components of the test item as far as possible within a reasonable time period. After stirring, the emulsions were filtered through a 0.45 μm membrane filter (Whatman, NC45). As a pre-caution, the filter was pre-conditioned with 200 mL filtrate to avoid losses of dissolved test item due to adsorption on the filter material. The undiluted filtrates were tested as WAFs.
- Eluate: no
- Differential loading: yes
- Controls: yes, test medium control
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: water flea
- Source: in-house culture (originally obtained from the Daphnia Collection of the University of Basel/Switzerland in 2015)
- Feeding during test: no
- Age: < 24 h

BREEDING
- Breeding conditions (same as test or not): same as test
- Type and amount of food: Fed with an algal suspension of the green algae Desmodesmus subspicatus supplied by the Collection of Algal Cultures (SAG, Institute for Plant Physiology, University of Göttingen, Germany) and cultivated at the laboratory under standardized conditions or a mixture of this algal suspension and a commercial fish diet (Tetra Min® Hauptfutter, supplied by TETRA-Werke, Melle, Germany).
- Feeding frequency: three times a week
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
250 mg CaCO3/L
Test temperature:
20 - 21 °C
pH:
7.7 - 7.9
Dissolved oxygen:
8.0 - 8.6 mg O2/L (0 h)
8.4 - 8.7 mg O2/L (48 h)
Nominal and measured concentrations:
nominal loading rates: control, 6.25, 12.5, 25, 50, 100 mg/L
measured (0 h): < LOQ, not measured, not measured, not measured, 0.512 mg/L, 0.936 mg/L
measured (48 h): < LOQ, not measured, not measured, not measured, 0.0672 mg/L (estimated, < LOQ), 0.151 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: beakers
- Type: covered with glass plates
- Material, size, headspace, fill volume: glass, 100 mL, headspace: 50 mL, fill volume: 50 mL
- Aeration: no
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted test water according to guideline

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 h light, 8 h darkness with 30 min transition period
- Light intensity: 15 - 17 µmol m-2 s-1

EFFECT PARAMETERS MEASURED
- Mobility after 24 and 48 h

RANGE-FINDING STUDY
- Test concentrations: control, 1.0, 10, 100 mg/L loading rate
- Results used to determine the conditions for the definitive study: 50% immobilisation at WAF loading rate of 100 mg/L
Reference substance (positive control):
yes
Remarks:
potassium dichromate (tested twice a year)
Key result
Duration:
48 h
Dose descriptor:
EL50
Effect conc.:
89 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EL0
Effect conc.:
50 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EL100
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Mortality of control: 0%
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: Test solutions were clear and colorless.
Results with reference substance (positive control):
- Results with reference substance valid? yes
- Relevant effect levels: EC50 (24 h): 1.2 mg/L (tested in March 2017)
- Other: The effect level is within the range given by the guideline (0.60 - 2.1 mg/L)
Reported statistics and error estimates:
The EL50 (48 h) could not be calculated by Probit Analysis or Moving Average Interpolation due to the steep concentration-effect relationship. Instead, the EL50 (48 h) was calculated by linear interpolation of the immobility between the two consecutive test concentrations with 0 and 60 % immobility on a semi-logarithmic scale (the 95% confidence limits could not be determined).

Table 1: Mobility of Daphnia magna after 24 and 48 h

Loading rate [mg/L]

No of Daphnids

Immobilized Daphnids after 24 h

Immobilized Daphnids after 48 h

No.

%

No.

%

Control

20

0

0

0

0

6.25

20

0

0

0

0

12.5

20

0

0

0

0

25

20

0

0

0

0

50

20

0

0

0

0

100

20

8

40

12

60

Table 2: Measured concentrations of WAF loading rates

Sampling Day/Sample Age [d/h]

WAF loading rate [mg/L]

Measured concentration [mg/L]

Sample preparation factor

Determined concentration of test item [mg/L]

% of initially measured concentration

0/0 (fresh)

Control

n.d.

0.1

< LOQ

-

50

5.12

0.1

0.512

-

100

9.36

0.1

0.936

-

2/48 (aged)

Control

< LOQ

0.1

n.a.

-

50

0.672

0.1

0.0672*

13

100

1.51

0.1

0.151

16

n.d. = no test item detected

n.a. = not applicable

* Estimated value, the determined concentration was below the LOQ.

LOQ: 0.115 mg/L

Table 3: Validity criteria

Criterion from the guideline

Outcome

Validity criterion fulfilled

In the control, including the control containing the solubilising agent, not more that 10% of the daphnids should have been immobilized.

0%

yes

The dissolved oxygen concentration at the end of the test should be ≥ 3 mg/L in control and test vessels.

8.4 - 8.7 mg O2/L

yes

 

Validity criteria fulfilled:
yes
Remarks:
For further details please refer to “Any other information on results incl. tables”.
Conclusions:
The test substance caused immobilisation of Daphnia magna according to OECD 202 (GLP). An EL50 (48 h) of 89 mg/L was calculated based on the nominal loading rates.

Description of key information

EL50 (48 h): 89 mg/L (nominal, OECD 202)

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
89 mg/L

Additional information

One experimental study is available investigating the short-term toxicity of the test item to aquatic invertebrates. The acute toxicity of the test item to Daphnia magna was determined in a 48-hour static test according to OECD 202 (2004) under GLP conditions. Since the test item is a complex mixture (UVCB) consists of several constituents with differently low solubility, Water Accommodated Fractions (WAFs) with the loading rates of 6.25, 12.5, 25, 50 and 100 mg/L were tested to assess the toxicity of the test item to daphnids. Additionally, a control group (test water without test item) was tested in parallel. The actual test concentrations in the test medium of the two highest loading rates were verified by GC/FID measurement at the start and end of the test. At the start of the test, the measured concentrations of the analyzed components of the test item in the test media with loading rates of 50 and 100 mg/L were 0.51 and 0.94 mg/L, respectively. The measured concentrations at the end of the test were in the range of 13 and 16 % of the initially measured values. The 48-hour EL50 was calculated (based on loading rates) to be 89 mg/L. Since WAFs were tested, all reported biological results were based on the loading rates of the test item. The preparation of the WAFs and procedure of evaluation of data of WAFs is based on recommendations of the OECD Guidance Document No. 23 on Aquatic Toxicity Testing of Difficult Substances and Mixtures, 2000.