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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
Study period:
20 January 2020 - 08 February 2020
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method C.1 (Acute Toxicity for Fish)
Version / remarks:
Regulation (EC) 440/2008
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
Version / remarks:
2019
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch number of test material: Chemring Nobel, Lot DDP17K0188-0002, Charge no. 180004
- Expiration date of the lot/batch: 05 February 2028
- Purity test date: Inspection date 22 February 2018

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature in the dark


Analytical monitoring:
yes
Details on sampling:
- Concentrations: All dose levels: Range finding test nominal concentrations 1.0, 10 and 100 mg/L
Main test nominal concentration: 100 mg/L
- Sample storage conditions before analysis: Not applicable - the test samples were analysed on the day of sampling
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
A nominal amount of test item (2000 mg) was dissolved in test water with the aid of ultrasonication for approximately 5 minutes and the volume adjusted to 1 liter to give a 2000 mg/L stock solution. This stock solution was dispersed in a total volume of 20 liters of test water to give the required test concentration of 100 mg/L.
The stock solution was inverted several times to ensure adequate mixing and homogeneity. The test preparation was stirred for approximately 1 minute with a flat bladed stirrer to ensure adequate mixing and homogeneity.
The concentration and stability of the test item in the test preparations were verified by chemical analysis at 0, 24, 72 and 96 hours.
Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Details on test organisms:
TEST ORGANISM
- Common name: Rainbow Trout
- Age at study initiation: Juvenile
- Length at study initiation: 5.1 cm (standard deviation 0.24)
- Weight at study initiation: 1.15 g (standard deviation 0.19)

ACCLIMATION
- Acclimation period: 7 days
- Acclimation conditions: Same as main test
- Type and amount of food during acclimation: Commercial trout pellets , discontinued approximately 24 hours before the definitive test
- Health during acclimation: No deaths seen in the 7 days before the start of the test
Test type:
semi-static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
96 h
Hardness:
140 mg/L as CaCO3
Test temperature:
13°C (measured value at all timepoints 0, 24, 48, 72 and 96 hours; 24, 48 and 72 hours timepoints refer to both expired and fresh media).
pH:
6.7 - 8.5
Dissolved oxygen:
9.6 - 11.9 mg O2/L
Nominal and measured concentrations:
Main (limit) test, Nominal concentration = 100 mg/L. Measured concentrations = 99.2 - 107 mg/L
Details on test conditions:
TEST SYSTEM
- Type: Covered to reduce evaporation
- Material, size, headspace, fill volume: Glass, 25 litre caparity, 20 litres fill volume
- Renewal rate of test solution: Daily
- No. of organisms per vessel: 7
- No. of vessels per concentration: 1
- No. of vessels per control: 1
- Biomass loading rate: 0.40 g body weight/liter

OTHER TEST CONDITIONS
- Adjustment of pH: None
- Photoperiod: 16 hours light / 8 hours dark
- Light intensity: The study plan defined the acceptable range as 540 - 1000 lux. In the range finding test at 24, 72 and 96 hours the measured light intensity was found to have exceeded this range (1003 - 1008 lux). On the basis that no adverse effects to exposure were observed in any of the control or test concentrations and the values were only slightly outside of the acceptable range, this deviation was considered to have had no adverse effect on the outcome or integrity of the test.

EFFECT PARAMETERS MEASURED: Any mortalities and sub-lethal effects of exposure were recorded at 1, 3, 6, 24, 29, 48, 53, 72, 77 and 96 hours after the start of exposure. The criteria of death were taken to be the absence of both respiratory movement and response to physical stimulation.

Based on the results of a preliminary range-finding test (test concentrations: 1, 10 and 100 mg/L) a limit test at a single concentration of 100 mg/L was used for the definitive test.
Reference substance (positive control):
no
Key result
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Key result
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Details on results:
There were no mortalities in seven fish exposed to a test concentration of 100 mg/L for a period of 96 hours.
There were no sub lethal effects of exposure observed in the test.

The control preparations were observed to be clear colorless solutions throughout the test, whilst the 100 mg/L test preparations were observed to be yellow colored clear solutions.

The test was considered to be valid given that none of the control fish died or showed signs of stress during the test and that the oxygen concentration at the end of the test was equal to or greater than 60% of ASV in the control and test vessels.

Validity criteria fulfilled:
yes
Conclusions:
The acute toxicity of the test item to the freshwater fish rainbow trout (Oncorhynchus mykiss) has been investigated and based on the nominal test concentration gave a 96 Hour LC50 of greater than 100 mg/L. The No Observed Effect Concentration (NOEC) was 100 mg/L.

Description of key information

LC50, 96 hours, Rainbow Trout (Oncorhynchus mykiss (previous name: Salmo gairdneri)) > 100 mg/L.

Based on ECOSAR v.1 (EPISUITE, 2009), the test substance, NTO, was predicted to have LC50 of 1760.072 mg/L after 96 hours exposure.

Key value for chemical safety assessment

Additional information