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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
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: Test guideline under Japan Chemical Substances Control Law
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
Lot No.:140220
Analytical monitoring:
yes
Details on sampling:
Rangefinder:
No samples were taken for analysis. A preliminary solubility trial was conducted prior to the range finder, which included prolonged stirring (48 hours), followed by filtration (Millex 0.45 um) of a 100 mg/L stock (in triplicate). This provided a mean solubility of 6.8 mg/L, which was used as the limit concentration in the definitive test.

Definitive:
- Concentration: 6.8 mg/L
- Frequency: Samples for analysis were taken from the limit test concentration, control and solvent control at the start of the study (t = 0h Fresh), (t = 48h Expired), (t = 48h Fresh) and (t = 96h Expired). This provided two sets of fresh and expired samples.
- Sampling method: 0.75 mL of medium used. No detail of where this was removed but assumed from the centre of the tanks.
- Sample storage conditions before analysis: Not detailed, but assumed to be analysed on the day of sampling.
Vehicle:
yes
Details on test solutions:
Preparations of test medium started with the preparation of a solvent stock solution in N,N-Dimethylformamide with the test material. An aliquot of this was then added into a media bottle containing test medium and stirred for 15 minutes (magnetically) which provided the limit concentration of 6.8 mg/L. This was then transferred to a 5L glass aquaria and mixed with a glass rod. An equivalent amount of solvent was added for the solvent control (vehicle) group. All prepared test solutions were clear and colourless.
Test organisms (species):
Oryzias latipes
Details on test organisms:
TEST ORGANISM
- Common name: Medaka
- Source: Kitamura-yourijou (388 Gunchiku 12-bancho, Yatsushiro, Kumamoto, Japan).
- Length at study initiation: 2.39 cm (Range 2.13-2.72 cm, n=10)
- Weight at study initiation: 0.131g (Range 0.101-0.177g, n=10)
(Weight/length values measured for the control fish at the end of the testing period (96 hours)).
- Feeding during test: no feeding for 24 hours prior to test and during test period.

ACCLIMATION
- Acclimation period: at least 14 days
- Feeding frequency: daily with Tetramin and/or Tetrawerke
- Health during acclimation (any mortality observed): < 5% mortality during 7 days prior to start of test
Test type:
semi-static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
96 h
Post exposure observation period:
Fish assumed to be euthanised after the test (96 hours). No detail provided.
Hardness:
57 mgCaCO3/L (Most recently available diluent water analysis).
Test temperature:
23.8 to 24.3°C
pH:
7.2 to 7.6
Dissolved oxygen:
7.8 to 8.5 mg/L
Nominal and measured concentrations:
The nominal concentration was 6.8 mg/L.
The measured concentrations were 93% at 0 hours (Fresh), 90% at 48 hours (expired), 96% at 48 hours (Fresh) and 97% at 96 hours (Expired), providing a time weighted mean value of 94% of nominal (6.39 mg/L measured)
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: 5L (Glass)
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- Biomass loading rate: 1.0g fish/ litre or less


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Dechlorinated water processed by treating tap water with an activated charcoal filter, and sodium thiosulphate
- Test medium: Dechlorinated water with the following composition:
Ca2+ 16 mg/L
Mg2+ 4.3 mg/L
Na+ 7.0 mg/L
K+ 1.0 mg/L
Cl- < 0.1 mg/L
HCO3(-) 57 mg/L
- Intervals of water quality measurement: daily

OTHER TEST CONDITIONS
- Photoperiod: 16 hours light, 8 hours dark, daily (1000 Lux or less)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Mortality and effect observations at 3, 24, 48, 72 & 96 hrs following the start of exposure

TEST CONCENTRATIONS
- Spacing factor for test concentrations: limit test 6.8 mg/L (limit of solubility in test medium)
- Justification for using less concentrations than requested by guideline: no toxicity at limit concentration
- Range finding study:
Test concentrations: 0.068, 0.68 and 6.8 mg/L
- Results used to determine the conditions for the definitive study: no toxicity observed
Reference substance (positive control):
yes
Remarks:
Aqueous Copper Sulphate
Key result
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
> 6.39 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Remarks on result:
other: Greater than limit of solubility
Key result
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
6.39 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Details on results:
No mortality or sublethal effects were noted at any point in either control, solvent control or test vessels in the main study
Results with reference substance (positive control):
- Results with reference substance valid? yes
- LC50: 0.62 mg/L (confidence limit: 0.42 - 0.89 mg/L). Within historical range.
Validity criteria fulfilled:
yes
Conclusions:
In a 96 hr acute toxicity study, Medaka (Oryzias Latipes) were exposed to the test substance at nominal concentrations of 0 (control), 0 (solvent control) and 6.39 mg/L under semi-static conditions (measured concentrations). Due to the low solubility of the test substance in the test medium, concentration levels that might be toxic for fish could not be reached. The 96hr LC50 was therefore above the solubility limit of the test substance in test medium (> 6.39 mg/L).

The NOEC value, based on mortality/sublethal effects, was 6.39 mg/L.

The limit test concentration was determined to be the limit of solubility in the test media, based on the results of a preliminary solubility trial.
 
This toxicity study is classified as acceptable and satisfies the guideline requirement for an acute fish toxicity study.

Description of key information

In a 96hr acute toxicity study, Medaka (Oryzias Latipes) were exposed to the test substance at measured concentrations of 0 (control), 0 (solvent control) or 6.93 mg/L under semi-static conditions. The NOEC value, based on mortality/ sublethal effects, was 6.93 mg/L.

Key value for chemical safety assessment

Additional information

Due to the low solubility of the test substance in test medium, concentration levels that might be toxic for fish could not be reached.The 96hr LC50 was above the solubility limit of the test substance in test medium (> 6.93 mg/L).

The NOEC value, based on mortality/ sublethal effects, was 6.93 mg/L.