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Short-term toxicity to fish

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Reference
Endpoint:
short-term toxicity to fish
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
Version / remarks:
1992
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
Samples of the test solutions at the beginning and the end of the renewal period, i.e. when it is freshly prepared and immediately prior to renewal or at the end of exposure are referred to as one set. The two sets of test solutions, one at the beginning of the exposure (0 hours) and before renewal at 24 hours and the other after renewal at 72 hours and at the end of the exposure (96 hours) were analysed.

Samples not stored prior to analysis.

Vehicle:
no
Details on test solutions:
The substance was poorly-soluble. A water-soluble fraction (WSF) was used to expose the test species to the test substance.

PREPARATION OF TEST SOLUTIONS

1) Preparation of stock solution
Test substance = 200 mg
Addition of dechlorinated wtaer
Final volume = 2000mL
Vessel = 2L media bottle
Loading rate = 100 mg/L
Frequency = 24h before the start of exposure and 24 hours before renewal of test solutions

2) Mixing method
The solution above was stirred with a magnetic stirrer for 24h (room temperature, approx. 24°C)

3) Collection of WSF
The stirred solution was filterated (Aspirator, WP-15, Yamato Scientific Co., Ltd) with filter (Membrane filter HA 0.45 um, Merck Millipore)
The filtrate was used as a stock solution

4) Preparation of test solution
To prepare the test solutions, stock solution was collected and diluted accordingly for the test concentrations

Stock solution + Dechlorinated water = final volume 5L
5L glass vessel. Mixing method, stirred with glass rod

Test solution of control = dechlorinated water
Test solution was aerated before use in order that dissolved oxygen concentration would reach 7.5 mg/L

Test organisms (species):
Oryzias latipes
Details on test organisms:
TEST ORGANISM
- Common name: Medaka
- Strain: Oryzias latipes
- Source: Kitamura-yourijou
- Age at study initiation: Less than 6 months after hatching
- Length at study initiation (mean and range): 2.34cm (2.13 - 2.67cm), n=9
- Weight at study initiation (mean and range): 0.107g (0.08 - 0.140g), n=9

ACCLIMATION
- Acclimation period: February 12 - March 4 2019
- Acclimation conditions:
Water: Dechlorinated water
Procedure: Flow-through (Biomass loading: 1g fish/L/day or less)
Temperature: 24°C +/- 1°C
Dissolved oxygen concentration (DO): 80% or more of saturation
pH: 6.0 - 8.5
Light: Fluorescent light, 16-hours light (1000 lux or less) / 8-hours dark
- Type and amount of food during acclimation: TetraMin, TetraWerke; approx. 2% of the body weight/day
- Feeding frequency during acclimation: Daily until 24 hours before exposure
- Health during acclimation (any mortality observed): Less than 5% mortality

FEEDING DURING TEST : no
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Remarks on exposure duration:
Standard for guideline study
Post exposure observation period:
Not applicable
Hardness:
52 mg CaCO3/L
Test temperature:
24°C +/- 1°C
pH:
Not adjusted
Dissolved oxygen:
60% or more of saturation (not aerated)
Conductivity:
13 mS/m
Nominal and measured concentrations:
1.0, 1.8, 3.2, 5.6, 10 mg/L (nominal); 0.494, 0.891, 1.59, 2.83, 4.93 (mean measured)
Details on test conditions:
TEST SYSTEM
- Test vessel: 5.0L glass vessel (cover: clear polyvinyl chloride (PVC) plate)
- Aeration: not aerated
- Renewal rate of test solution (frequency): Batchwise renewal of the test solution after every 24-hours exposure
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- No. of vessels per vehicle control (replicates): 1
- Biomass loading rate: 1g fish/L or less

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Dechlorinated water was processed by treating Yokohama city tap water with an activated charcoal filter and sodium thiosulphate
- Total organic carbon: 0.3 mg/L
- Particulate matter: Not detected
- Metals: Not detected
- Pesticides: Not detected
- Alkalinity: 35 mg CaCO3/L
- Intervals of water quality measurement: approx. every 6 months

OTHER TEST CONDITIONS
- Adjustment of pH: not adjusted
- Photoperiod: 16h light, 8h dark
- Light intensity: 1000 lux or less

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Death, abnormal behaviour. Observed at 3, 24, 48, 72 and 96h after the start of exposure

TEST CONCENTRATIONS
- Spacing factor for test concentrations: As guideline (1.78)
- Range finding study
- Test concentrations: 1, 10, 100 mg/L nominal
- Results used to determine the conditions for the definitive study: yes
Reference substance (positive control):
yes
Remarks:
CuSO4(II).5H2O
Key result
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
2.39 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
mortality
Remarks on result:
other: 95% confidence limits
Remarks:
1.83 - 3.26
Duration:
96 h
Dose descriptor:
LC0
Effect conc.:
1.59 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
mortality
Duration:
96 h
Dose descriptor:
LC100
Effect conc.:
4.93 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
mortality
Details on results:
- Behavioural abnormalities:
- Mortality of control: 10%
- Other adverse effects control:
- Abnormal responses: see table ?? below
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no suspended, floating substance or precipitation


Temperature ranged from 23.5 to 23.9°C
DO ranged from 6.6 to 8.5 mg/L
pH ranged from 6.8 to 7.2
Results with reference substance (positive control):
- Results with reference substance valid? Yes, within historical range for laboratory
- Mortality: yes
- 96h LC50: 0.49 mg/L
Reported statistics and error estimates:
Probit method, moving average mothed and binomial method
Validity criteria fulfilled:
yes
Remarks:
Mortality in control not more than 10%; DO concentration above 60% of saturated solution
Conclusions:
The results of the test show that the test substance is acutely toxic to fish. (96h LC50: 2.39 mg/L)

Description of key information

OECD guideline, GLP compliant study. Japanese medaka were exposed to the test substance for 96 hours during the test. % of mortality and abnormal behaviours were recorded.

96h LC50 value of 2.39 mg/L was calculated.

Key value for chemical safety assessment

LC50 for freshwater fish:
2.39 mg/L

Additional information