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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Data from the related substance imazalil base is used to cover this endpoint. The justification for read across is attached in IUCLID Section 13.
Reason / purpose for cross-reference:
read-across source
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
4.66 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
imazalil sulfate (recalculated from imazalil concentration)
Basis for effect:
mortality
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
27 March to 5 April 1990
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: BEB191
- Expiration date of the lot/batch: not indicated
- Purity test date: not indicated

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: not indicated
- Stability under test conditions: not indicated







Analytical monitoring:
yes
Details on sampling:
- Concentrations: 1.8, 3.2, 5.6, 10, 18, 32 mg/l
- Sampling method: samples of +- 20 ml were taken
- Sample storage conditions before analysis: samples were stored at -20°C in a deep freezer until analysis of the test substance concentration
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:
Two stock solutions were prepared:
* a saturated solution of imazalil in dilution water for the preliminary test
* 100 mg of imazalil per litre of dilution water for the confirmatory test
As the solubility of imazalil was 180 mg/l, the saturated solution was prepared by adding +- 500 mg imazalil to 1 litre of dilution water. The mixture was placed in an ultrasonic water bath for 30 minutes. Next, the mixture was stirred for 30 minutes. This procedure was repeated and finally the mixture was filtered through a filter-papaer (S & S).
The 100 mg imazalil per litre stock solution was prepared by dissolving 100 mg in 1 litre of dilution water.

- Controls: yes
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: water flea
- Strain/clone: not indicated
- Source: Obtained in 1986 from the State University of Ghent, Laboratory for Biological Research in Aquatic Pollution, Ghent, Belgium. Daphnias for the test were taken from a stock culture held in the Janssen laboratory.

METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES:
On the day preceding test initiation, daphnids which already had 2 healthy broods were sieved through a stainless steel sieve of 20 mesh in order to separate the offspring from the parents. The offspring produced by the adults within the day preceding the test is guaranteed younger than 24h.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
240 mg/l CaCO3
Test temperature:
21.2 °C
pH:
7.83
Dissolved oxygen:
29.6 mg/l O2
Salinity:
not relevant
Conductivity:
not relevant
Nominal and measured concentrations:
Nominal concentration: 1.8, 3.2, 5.6, 10, 18, 32 mg/l
Measured concentration (t=0h): 1.7, 3.2, 5.5, 9.2, 16.5, 28.3 mg/l (test substance solution)
Measured concentration (t=48h): 1.825, 3.175, 5.625, 10.35, 17.65, 30.4 mg/l (mean measured concentration)
Details on test conditions:
TEST SYSTEM
- Test vessel: glass tubes
- Material, size, headspace, fill volume: all-glass test tubes of +- 90 ml, calibrated at 50 ml
- 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:
* NaHCO3 64.75 mg/l
* KCl 5.75 mg/l
* CaCl2.2H2O 294.00 mg/l
* MgSO4.7H2O 123.25 mg/l
* K2-EDTA.2H2O 1.086 mg/l
* FeCl3.6H2O 1.500 mg/l
* MnSO4.H2O 0.031 mg/l
* Na2MoO4.2H2O 0.013 mg/l
* ZnSO4.7H2O 0.004 mg/l
* SeO2 0.001 mg/l
* Vitamine B12 0.001 mg/l

OTHER TEST CONDITIONS
- Photoperiod: in the dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
The number of immobile daphnids in each group was determined daily. Daphnids not being able to swim within 15 sec. after gentle agitation of the test tube were considered as immobile.

RANGE-FINDING STUDY
- Test concentrations: 0.1, 1, 10, 100% of the saturated solution
- Results used to determine the conditions for the definitive study: yes
Reference substance (positive control):
no
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
6.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% confidence limits: 6.3 - 6.3 mg/l
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
3.5 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% confidence limits: 2.6 - 4.7 mg/l
Details on results:
- Behavioural abnormalities: no
- Mortality of control: no
- Other adverse effects control: none indicated
- Abnormal responses: none indicated
Reported statistics and error estimates:
Probit analysis, following the method of Finney, was applied to determine the EC50 - 24h / 48h (median effective concentration after 24 and 48 h) and its 95% confidence limits. The homogeneity of the data was tested with chi-square statistics.
Validity criteria fulfilled:
yes
Conclusions:
The acute toxicity of Imazalil to Daphnia magna was determined in a 48 hour static test according to OECD guideline 202.The EC50 - 48h value (median effective concentration after 48h) with respect to immobilization was 3.5 mg imazalil per litre. The results of the test can be considered reliable without restriction.

Description of key information

The study of Weytjens (1990), investigating the acute toxicity of Imizalil in Daphnia magna according to OECD guideline 202, was considered as the key study for endpoint coverage. An EC50 of 3.5 mg imazalil /L was found after an exposure of 48 hours in a static test in freshwater which corresponds to 4.66 mg imazalil sulphate/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
4.66 mg/L

Additional information