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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
27 November 2017 - 17 January 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report date:
2018

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide
EC Number:
253-021-4
EC Name:
2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide
Cas Number:
36411-52-6
Molecular formula:
C9H8N4O2
IUPAC Name:
2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide
Test material form:
solid: particulate/powder
Details on test material:
Batch:102Z5
Purity: 99.9%
white powder

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
- Concentrations: 50mg/L (100% saturated solution v/v)
Samples were taken from the control and the 100% v/v saturated solution test group from the bulk test preparation at 0 hours and from the pooled replicates at 48 hours for quantitative analysis. All samples were stored frozen prior to analysis. Duplicate samples were taken at 0 and 48 hours and stored frozen for further analysis if necessary.

Test solutions

Vehicle:
yes
Remarks:
Reconstituted water (Elendt M7 medium)
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
The water solubility of the test item was found to be less than 0.1 g/L. Preliminary solubility work conducted indicated that it was not possible to obtain a testable solution of the test item using traditional methods of preparation e.g. ultrasonication and high shear mixing. Based on this information the test item was categorized as being a ‘difficult substance’ as defined by the OECD Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures (OECD 2000).
The results obtained from the preliminary media preparation trial conducted indicated that a dissolved test item concentration of approximately 3.4 mg/L could be obtained using a saturated solution method of preparation.
The test concentration to be used in the definitive test was determined by a preliminary range-finding test.
In the range-finding test Daphnia magna were exposed to a series of nominal test concentrations of 0.10, 1.0, 10 and 100% v/v saturated solution.
A nominal amount of test item (550 mg) was dispersed in 11 liters of test water with the aid of propeller stirring at approximately 1500 rpm for 24 hours. After 24 hours the stirring was stopped and any undissolved test item was removed by filtration through a 0.2 μm Sartorius Sartopore filter (first approximate 2 liters discarded in order to pre-condition the filter) to give a 100% v/v saturated solution. A series of dilutions was made from this saturated solution to give further test concentrations of 0.10, 1.0 and 10% v/v saturated solution.

Test organisms

Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Justification for species other than prescribed by test guideline: guideline
- Source: in house cultures
- Feeding during test: algal suspension (Desmodesmus subspicatus) and Tetramin® flake food suspension
- Frequency: daily

ACCLIMATION
Adult daphnids were maintained in 150 mL glass beakers containing 100 mL Elendt M7 medium in a temperature controlled room maintaining the water temperature at 18 to 22 °C. The lighting cycle was controlled to give a 16 hours light and 8 hours darkness cycle with 20 minute dawn and dusk transition periods.

Study design

Test type:
static
Water media type:
other: Reconstituted water (Elendt M7 medium)
Limit test:
no
Total exposure duration:
48 h

Test conditions

Hardness:
not specified
Test temperature:
20 to 23 °C throughout the test
pH:
7.8 - 8.0
Dissolved oxygen:
8.9 - 9.2
Salinity:
not specified
Conductivity:
not specified
Nominal and measured concentrations:
measured: 18mg/L at 0 hours, 22mg/L at 48 hours
nominal: 20mg/L
Details on test conditions:
TEST SYSTEM
150 mL glass jars containing approximately 100 mL of test preparation were used. At the start of the test five daphnids were placed in each test and control vessel at random, in the test preparations. Four replicate test and control vessels were prepared. The test vessels were then covered to reduce evaporation and maintained in a temperature controlled room maintaining the water temperature at 18 to 22 °C with a maximum deviation of ±1 °C with a photoperiod of 16 hours light (between 200 and 1200 Lux) and 8 hours darkness with 20 minute dawn and dusk transition periods. The daphnids were not individually identified, received no food during exposure and the test vessels were not aerated.
The control group was maintained under identical conditions but not exposed to the test item.
The test preparations were not renewed during the exposure period.

RANGE-FINDING STUDY
- Test concentrations: 0.10, 1.0, 10 and 100% v/v saturated solution
- Results used to determine the conditions for the definitive study: yes
Reference substance (positive control):
yes

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
> 20 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 20 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
24 h
Dose descriptor:
NOEC
Effect conc.:
> 20 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
> 20 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Behavioural abnormalities:
The geometric mean measured test concentration was determined to be 20 mg/L. There was no immobilization in 20 daphnids exposed to a test concentration of 20 mg/L for a period of 48 hours.
The NOEC after 24 and 48 hours exposure was 20 mg/L. No sub-lethal effects of exposure were observed throughout the test.
The test was considered to be valid given that none of the control daphnids showed immobilization or other signs of disease or stress and that the oxygen concentration at the end of the test was equal to or greater than 3 mg/L in the control and test vessels.
Results with reference substance (positive control):
- Results with reference substance valid? yes
- EC50: 0.79 mg/L at 24 hours, and 0.75 mg/L at 48 hours
Reported statistics and error estimates:
not specified

Applicant's summary and conclusion

Validity criteria fulfilled:
not specified
Conclusions:
The acute toxicity of the test item to the freshwater invertebrate Daphnia magna has been investigated and based on the geometric mean measured test concentration gave a 48 hour EC50 value of greater than 20 mg/L. The NOEC was 20 mg/L.
This study showed that there were no toxic effects at saturation.

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