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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2018-07-20 to 2018-09-25
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)
Version / remarks:
13th April 2004
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Version / remarks:
31 May 2008
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)
Version / remarks:
April 1996
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and batch No. of test material: OUCHI SHINKO CHEMICAL INDUSTRIAL CO., LTD.; 608011
- Expiration date of the lot/batch: 2018-08-31

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Keep to the storeroom with suitable ventilation. Avoid fire, direct sunlight and moisture. Store at room temperature.
Analytical monitoring:
yes
Details on sampling:
For determination of the test item concentrations, samples were taken from each test concentration at the start and at the end of the test and from the control at the start and at the end of the test.
Replicates and volume of samples are detailed below:
Control: 1×2 mL
0.625 mg/L: 4×2 mL
1.25 mg/L: 4×2 mL
2.5 mg/L: 4×2 mL
5.0 mg/L: 4×2 mL
10.0 mg/L: 4×2 mL
Vehicle:
no
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: water flea
- Strain/clone: Straus
- Age at study initiation: Less than 24 hours old
- Method of breeding: Daphnia were bred in the Laboratory of TOXI-COOP ZRT. under similar temperature and light conditions as in the test, and in reconstituted water of a similar quality regarding to pH, components of the main ions and total hardness as the test water used in the test. Daphnids were fed with centrifuged green alga suspension.
- Source: Laboratory of Hydrobiology (Central Agricultural Office, Directorate of Plant-, and Soil Protection) 2100 Gödöllő, Kotlán S. u. 3. Hungary

ACCLIMATION
- Acclimation period: Test animals were bred under similar conditions as that used during the exposure period, therefore additional acclimatisation before the test was not necessary.
- Acclimation conditions: same as test
- Type of food: green alga suspension
- Health during acclimation (any mortality observed): No
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
249 mg/L (as CaCO3)
Test temperature:
18°C and 22°C
pH:
6-9
Dissolved oxygen:
≥ 3 mg/L
Nominal and measured concentrations:
nominal: 0.625, 1.25, 2.5, 5.0 and 10.0 mg/L
measured: 0.24, 0.55, 1.25, 2.71 and 5.46 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Beaker
- Material, fill volume: glass, 40 mL
- Aeration:
- 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: ISO medium
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: 16 hours light and 8 hours dark

EFFECT PARAMETERS MEASURED: The immobility or mortality of the Daphnia was determined by visual observation after 24 and 48 hours of exposure. Those animals not able to swim within 15 seconds after gentle agitation of the test beaker were considered to be immobile.

VEHICLE CONTROL PERFORMED: yes

RANGE-FINDING STUDY
- Test concentrations: 100, 10, 1 and 0.1 mg/L
- Results used to determine the conditions for the definitive study: All daphnids were immobilised at 10 and 100 mg/L.
Reference substance (positive control):
no
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
1.34 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC10
Effect conc.:
0.95 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
0.55 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Behavioural abnormalities: No
- Immobilisation of control: Immobility was not observed in the untreated control group and no Daphnia were trapped at the water surface or showed any signs of disease or stress.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: No
- Effect concentrations exceeding solubility of substance in test medium: No
Reported statistics and error estimates:
The 48-h ECx values and their 95 % confidence limits were calculated by Probit analysis using SPSS software. The ECx values were calculated from the measured (geometric mean) concentrations.

Temperature

The test temperature was in the range of 20.7 – 21.4 °C measured in the test vessels during the test. The additionally measured ambient temperature within the climate chamber was between 20.4 – 21.7 °C.

Oxygen concentration

The dissolved oxygen concentration was in the range of 6.91 – 7.36 mg/L during the test.

pH

The pH of the test solutions was not adjusted and did not vary by more than 1.5 units. The pH was in the range of 7.55 – 7.95 during the test.

Validity criteria fulfilled:
yes
Conclusions:
In this 48-hour acute toxicity test on Daphnia magna, the obtained results showed that the test item Zinc di(benzimidazol-2-yl) disulphide had significant toxic effects on the mobility of Daphnia. The 48-h EC50 value was determined to be 1.34 mg/L. The 48-h NOEC was determined to be 0.55 mg/L. The results are based on measured test item concentrations.
Executive summary:

The 48–hr-acute toxicity of Zinc di(benzimidazol-2-yl) disulphide to Daphnia magna was studied under static conditions according to OECD guideline 202 (TOXICOOP, 2018). Test species were exposed to control, and test chemical at nominal concentrations of 0.625, 1.25, 2.5, 5.0 and 10.0 mg/L. The measured concentrations deviated more than 20 % from the nominal at the start and at the end of the experiment. Therefore, the geometric mean of the concentrations measured at the start and end of the test were calculated to determine exposure concentrations. Corresponding calculated geometric mean measured concentrations were: 0.24, 0.55, 1.25, 2.71 and 5.46 mg/L. Twenty animals, divided into four groups of five animals (glass beaker; approx. 40 mL test medium) each were exposed to the test concentrations or run as control for 48 hours in a static test. The immobility or mortality of the Daphnia was determined by visual observation after 24 and 48 hours of exposure.

The measured concentrations of the test item were in the range of 57 – 58 % of the nominal at the start and 26 – 52 % of the nominal at the end of the test. Biological results and endpoints are based on the measured geometric mean test item concentrations. The 48-h EC50 value was determined to be 1.34 mg/L. The 48-h NOEC was determined to be 0.55 mg/L and the 48-h LOEC was determined to be 1.25 mg/L (directly from the raw data). All validity criteria were met. The results are based on measured test item concentrations.

Description of key information

In this 48-hour acute toxicity test on Daphnia magna, the obtained results showed that the test item Zinc di(benzimidazol-2-yl) disulphide had significant toxic effects on the mobility of Daphnia. The 48-h EC50 value was determined to be 1.34 mg/L. The 48-h NOEC was determined to be 0.55 mg/L. The results are based on measured test item concentrations.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
1.34 mg/L

Additional information

The 48–hr-acute toxicity of Zinc di(benzimidazol-2-yl) disulphide to Daphnia magna was studied under static conditions according to OECD guideline 202 (TOXICOOP, 2018). Test species were exposed to control, and test chemical at nominal concentrations of 0.625, 1.25, 2.5, 5.0 and 10.0 mg/L. The measured concentrations deviated more than 20 % from the nominal at the start and at the end of the experiment. Therefore, the geometric mean of the concentrations measured at the start and end of the test were calculated to determine exposure concentrations. Corresponding calculated geometric mean measured concentrations were: 0.24, 0.55, 1.25, 2.71 and 5.46 mg/L. Twenty animals, divided into four groups of five animals (glass beaker; approx. 40 mL test medium) each were exposed to the test concentrations or run as control for 48 hours in a static test. The immobility or mortality of the Daphnia was determined by visual observation after 24 and 48 hours of exposure.

The measured concentrations of the test item were in the range of 57 – 58 % of the nominal at the start and 26 – 52 % of the nominal at the end of the test. Biological results and endpoints are based on the measured geometric mean test item concentrations. The 48-h EC50 value was determined to be 1.34 mg/L. The 48-h NOEC was determined to be 0.55 mg/L and the 48-h LOEC was determined to be 1.25 mg/L (directly from the raw data). All validity criteria were met. The results are based on measured test item concentrations.

A QSAR calculation using ECOSAR v1.11 determined a similar EC50 for short-term toxicity for Daphnia of 1.981 mg/L.