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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:
other: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
From October 10 to 21, 2016
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
Reliability of the source study is 1
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
2004
Deviations:
yes
Remarks:
Study performed without the analytical determination of the test substance concentrations. According to request of sponsor the test substance concentration control was performed by TOC method.
Qualifier:
according to guideline
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Version / remarks:
2008
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
Preparation of Sample Solutions: samples of test solutions were prepared and delivered by Ecotoxicity group. The samples were analysed in the day of delivery. The samples from preliminary test and samples from definitive test were analysed not diluted.
Vehicle:
yes
Details on test solutions:
The stock solution of the test substance was prepared in the dilution water. 50 mg of the test substance was weighed into 500 mL of the dilution water for the preliminary and for the definitive test. The concentrations of solutions used in the preliminary and definitive test were obtained by dilution of the stock solution with dilution water.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna Straus
- Source: obtained by aperiodic parthenogenesis from own laboratory breeding
- Food type: mixture of algae

The sensitivity of the test species is periodically monitored by testing with the reference substance, potassium dichromate.
The grow-up gravid females are separated into dilution water. Young daphnia born in 24 hours are segregated to the handling container from which they entered the experiment. At handling a care should be taken of not to penetrate the air under animal’s shell.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
2.52 mmol/l
Test temperature:
20 ± 2 °C, with a variation of ± 1 °C at each individual test
pH:
7.6
Dissolved oxygen:
higher than 3 mg/l
Conductivity:
2.26 µS/cm
Nominal and measured concentrations:
Preliminary test: 100, 50, 10, 5 and 1 mg/l (nominal concentration)
Definitive test: 50, 25, 13, 7, 4, 2 and 1mg/l (nominal concentration)
Details on test conditions:
TEST SYSTEM
- Aeration: no
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Dilution water was prepared just before the test by admixing 2.5 mL of stored solutions A, B, C and D into 1000 mL of deionized water. (A:117.6 g CaCl2•2H20 in 1L deionized water; B: 49.3 g MgSO4•7H2O in 1L deionized water; C: 25.9 g NaHCO3 in 1L deionized water; D:2.3 g KCl in 1L deionized water)
- sum Ca + Mg ions: 2.52mmol/l
- Conductivity: 1.33 µS/cm in the Preliminary test and 2.26 µS/cm in the Definitive test

OTHER TEST CONDITIONS
- Photoperiod: 16-hours light and 8-hours dark
- Volume of test substance solution: 50 mL (least 2 mL per individual)
- No feeding

RANGE-FINDING STUDY
- Test concentrations: from 1, 5, 10, 50, 100 mg/l
- Results used to determine the conditions for the definitive study: at 1 mg/l 0 % immobilisation; at 5 mg/l 30 % immobilisation; at 10 mg/l 50 % immobilisation; at 50 mg/l 70 % immobilisation; at 100 mg/l 100 % immobilisation.
Reference substance (positive control):
yes
Duration:
48 h
Dose descriptor:
EC0
Effect conc.:
ca. 2 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
ca. 6.8 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% confidence limit
Remarks:
5.4 – 8.5 mg/l
Duration:
48 h
Dose descriptor:
EC100
Effect conc.:
ca. 50 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
24 h
Dose descriptor:
EC0
Effect conc.:
ca. 2 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
ca. 10.4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% confidence limit
Remarks:
8.2 – 13.4 mg/l
Duration:
24 h
Dose descriptor:
EC100
Effect conc.:
ca. 50 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Results with reference substance (positive control):
Reference test
The sensitivity of the test species and correctness of test performance is periodically verified in six-month period by testing with the reference substance, potassium dichromate. The results of the verification test with K2Cr2O7,carried out in period from 13.04. to 15.04.2016 are the following: 24 hour – EC50= 1.17 mg·L-1(95% confidence limit: 1.03 – 1.37 mg·L-1) 48 hour – EC50= 0.62 mg·L-1(95% confidence limit: 0.52 – 0.72 mg·L-1)

Validity of the test

1. The test quality criteria

The following quality criteria are given in the guideline:

- Immobilisation in the controls must not exceed 10 % at the end of the test.

- The dissolved oxygen concentrations (throughout the test) should remain above 3 mg·L-1.

The test quality criteria were fulfilled.

 

2. Method validity monitoring

a) Interlaboratory test data

From the result of the last interlaboratory test arranged by CS labspol. s r.o.(accredited provider of proficiency testing) in 2016 we have obtained data for potassium dichromate 48h – EC50generated at 13 laboratories. The following reference range of values could be calculated from those data:

               48 hour–EC50= 0.46 – 1.08 mg·L-1

b) Method validity evaluation

The immobilisation of test organism by the reference substance (48hour – EC50) obtained from our last reference test meets the calculated range from the interlaboratory test. 

Validity criteria fulfilled:
yes
Conclusions:
EC50 (48h) = 6.8 mg/l
Executive summary:

Method

The substance was tested in acute immobilisation test on Daphnia magna, according to method C.2 – Daphnia sp. Acute Immobilisation Test, Council Regulation (EC) No. 440/2008.

The preliminary test was performed in a range of the test substance nominal concentrations 1 – 100 mg·L-1. Based on toxicity of the test substance found in the preliminary test, the definitive test was performed inappropriate concentration range. The definitive test was performed static, in a range of the test substance nominal concentrations 1 – 50 mg·L-1.

The study was performed without analytical determination of the test substance concentrations. Only the concentrations of Total organic carbon (TOC) in the lowest and in the highest tested concentration were analysed in the preliminary and definitive test. Samples for determination of the TOC concentrations were taken at the beginning and at the end of the test. The nominal concentrations were used for all evaluation and results.

Results

EC50 (48h) = 6.8 mg/l

Description of key information

EC50 (48h) = 6.8 mg/l

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
6.8 mg/L

Additional information