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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:
25.07.2017 to 27.07.2017
Reliability:
1 (reliable without restriction)
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
For determination of the test item concentrations samples were taken from each test item concentration and from the control at the start and at the end of the test. Four parallel samples were measured from the each test concentration and three replicates from the control sample (5 mL per repliate).
Vehicle:
no
Details on test solutions:
The test solutions used in the test was prepared by mechanical dispersion without using any solubilising agents. For preparation of test solutions a stock solution of 100 mg/L (nominal concentration) was first prepared by dissolving an amount of 0.05 g test item in 500 mL ISO medium. The test solutions of subsequent concentrations were prepared by appropriate dilution of this stock solution.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna (Straus)
- Source: Laboratory of Hydrobiology (Central Agricultural Office, Directorate of Plant-, and Soil Protection) 2100 Gödöllő, Kotlán S. u. 3. Hungary
- Age of parental stock (mean and range, SD): Less than 24 hours old
- Feeding during test: no

ACCLIMATION
- Acclimation period: no
- Acclimation conditions: same as test
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
approximate 249 mg/L
Test temperature:
20.1 – 20.5°C (test vessels), 20.1 – 21.0°C (climate chamber)
pH:
7.61 – 8.05
Dissolved oxygen:
7.92 – 8.28 mg/L
Salinity:
not specified
Conductivity:
not specified
Nominal and measured concentrations:
nominal concentrations: 6.25, 12.5, 25, 50 and 100 mg/L
geometric mean concentrations: 4.2, 7.9, 16.4, 34.0 and 67.8 mg/L.
Details on test conditions:
TEST SYSTEM
- Test vessel: glass beaker
- Medium volume per beaker: at least 40 mL
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

OTHER TEST CONDITIONS
- Photoperiod: 16 h light and 8 h darkness
- Light intensity: 649 lux

RANGE-FINDING STUDY
- Test concentrations: 1, 10 and 100 mg/L (plus control)
- Results used to determine the conditions for the definitive study: no immobilisation at 10 mg/L and below, 100% immobilisation at 100 mg/L
Reference substance (positive control):
yes
Remarks:
Potassium dichromate, experimantal phase: 07 – 08 March 2017
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
37.2 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
16.4 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
48 h
Dose descriptor:
LOEC
Effect conc.:
34 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Details on results:
- Behavioural abnormalities:
- Mortality of control: no immobilisation was observed in the control

No immobilisation observed in twenty daphnids exposed to control group and the in the treatment groups up ti iand including 25 mg/L (nominal). In the treatment group with the highest test item concentration (100 mg/L) all animals were found immobilized during 24 and 48 hours. In the second highest test item concentration (50 mg/L) ca. 40% of the animal were found immobilized during 24 and 48 hours.

Results with reference substance (positive control):
24h EC50: 1.41 mg/L (95 % confidence limits: 1.19 – 1.68 mg/L)
Reported statistics and error estimates:
For determination of the ECx values Probit analysis was performed using SPSS software. Other endpoints were determined directly from the raw data.
Validity criteria fulfilled:
yes
Conclusions:
In this 48-hour static acute toxicity test with Daphnia magna the effects of Bis(methyltio)methane on the mobility was determined. The 48-h EC50 value was determined to be 37.2 mg/L. The 48-h NOEC was determined to be 16.4 mg/L.
Executive summary:

The purpose of this study was to evaluate the influence of the test item Bis(methyltio)methane on the mobility, respectively survival of Daphnia magna in a static test system. Young Daphnia were exposed in an immobilisation test to aqueous test media containing the test item at 6.25, 12.5, 25, 50 and 100 mg/L ((corresponding to 4.2, 7.9, 16.4, 34.0 and 67.8 mg/L (calculated geometric mean measured concentrations)). Twenty Daphnia, divided into four groups of five animals each were exposed to the test item concentrations or run as control for 48 hours. The 48-h EC50 value was determined to be 37.2 mg/L. The 48-h NOEC was determined to be 16.4 mg/L.

Description of key information

The 48-h EC50 value of the test item on Daphnia magna was determined to be 37.2 mg/L.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
37.2 mg/L

Additional information

In the acute immobilisation test (reference 6.1.3-1) with Daphnia magna (STRAUS), the effects of the test item were determined according to OECD Guideline for testing of chemicals, Guideline No. 202, adopted 13th April 2004. The study was conducted in a static system over a period of 48 hours with nominal concentrations of 6.25, 12.5, 25, 50 and 100 mg/L (corresponding to geometric measured concentrations of 4.2, 7.9, 16.4, 34.0 and 67.8 mg/L). The validity criteria of the test guideline were fulfilled. The EC50 value (48 hours) was determined to be 37.2 mg/L (mean measured).