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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
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
This study was in accordance with the EC Guideline and GLP. The test substance was equivalent to submission substance identity but the degree of purity was not available. However, the substance formed an oily layer at the surface of the test solution which trapped some organisms. Therefore, the real tested concentration could have been lower than the nominal ones and physical effect may have interfered the interpretation of the results.
Reference:
Composition 0
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
GLP compliance:
yes
Remarks:
The certificate copy was not included in the study report
Test material information:
Composition 1
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The first day of the test, the vessel containing the test substance was heated at 30°C in a water-bath until the visual disappearance of “crysals”. The substance and the test medium were introduced, under magnetic stirring, in the test vessel in the following respective proportions: 0 (control), 1.0, 1.8, 3.3, 5.8 and 11 mg for 1000 g. One liter of test solution was prepared for each concentration. Each test solution, expected the control, was submitted to an ultrasound treatment (Bransonic 52; 50-55 kHz, 200 W) for one hour. After the ultrasound treatment, the test solution temperature has been stabilized at 20°C.
- Controls: One blank control was tested
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): no vehicle was used
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): not applicable
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no data available
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia
- Strain: Daphnia magna strauss 1820 IRCHA strain
- Source: INERIS, breeding in the test laboratory (i.e. Rhône-Poulenc Industrialisation)
- Age at study initiation (mean and range, SD): no data available
- Weight at study initiation (mean and range, SD): no data available
- Length at study initiation (length definition, mean, range and SD): 315-560 µm
- Valve height at study initiation, for shell deposition study (mean and range, SD): no data available
- Peripheral shell growth removed prior to test initiation: no data available
- Method of breeding: no data available
- Feeding during test: no data available
ACCLIMATION
No data available
QUARANTINE (wild caught)
No data available
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
No data available
Hardness:
No data available
Test temperature:
19.3 to 19.9°C
pH:
7.6 to 7.7 at 48 hours
The pH of the test solution was measured at 48 h in each test vessel of the definitive test (see table below)
Dissolved oxygen:
95 to 97% of saturation at 48 hours
The dissolved oxygen of the test solution was measured at 48 h in each test vessel of the definitive test (see table below)
Salinity:
No data available
Nominal and measured concentrations:
Nominal concentration: 0, 1.0, 1.8, 3.3, 5.8 and 11 mg/kg
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: Glassy beaker of 2 L
- Aeration: no data available
- Type of flow-through (e.g. peristaltic or proportional diluter): Not applicable. The test type was static.
- Renewal rate of test solution (frequency/flow rate): not applicable
- No. of organisms per vessel: 20
- No. of vessels per concentration (replicates): One. No replicate was used.
- No. of vessels per control (replicates): One. No replicate was used.
- No. of vessels per vehicle control (replicates): No vehicle control was performed.
- Biomass loading rate: 20 daphnids per liter of test solution
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The test medium was prepared with bidistilled water. Its composition was the following: CaCl2, 2H2O (0.294 g); MgSO4, 7H2O (0.12325 g); NaHCO3 (0.06475 g); KCl (0.00575 g); in Bidistilled water.
- Conductivity: 0.98 µS.cm-1
- pH: 8.0 at 20°C
- O2: 100% of saturation
- Culture medium different from test medium: no data available
- Intervals of water quality measurement: no data available
OTHER TEST CONDITIONS
- Adjustment of pH: no data available
- Photoperiod: No. The test was carried out in darkness.
- Light intensity: Not applicable.
EFFECT PARAMETERS MEASURED (with observation intervals if applicable):
Immobilization of Daphnia at 24 and 48 hours.
TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.8
- Justification for using less concentration than requested by guideline: not applicable
- Range finding study: No range finding study was performed.
Reference substance (positive control):
yes
Remarks:
Potassium dichromate (K2Cr2O7)
Duration:
24 h
Dose descriptor:
EC50
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: The EC50-24h would not be determined by the probit method because the model is invalid. The confidence limits at 95% were determined by the binomial method. They were 1 and 11 mg/kg
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
1.9 other: mg/kg
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: The EC50-48h was determined by the probit method. The confidence limits at 95% were 0.57 and 6.4 mg/kg
Details on results:
- Behavioural abnormalities: no data available
- Observations on body length and weight: no data available
- Other biological observations: no data available
- Mortality of control: No mortality was observed in the control
- Other adverse effects control: no data available
- Abnormal responses: no data available
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: In all the test concentrations, substance clusters were formed at the surface in which daphnids were trapped. At 11 mg/kg an oily layer was formed at the surface.
- Effect concentrations exceeding solubility of substance in test medium: no data.
Results with reference substance (positive control):
- Results with reference substance valid? Yes, the 24h EC50 value obtained with the reference substance is within the range of the accepted results (i.e. 0.6 – 1.7 ppm)
- Mortality: no data available
- LC50: 1.1 ppm (w/w) at 24 hours of exposure
- Other: 95% confidence limit: 0.97 to 1.3 ppm
Reported statistics and error estimates:
The confidence limits at 95% of EC50-24h were 1 and 11 mg/kg (binomial method)
The confidence limits at 95% of EC50-48h were 0.57 and 6.4 mg/kg (probit method)

Mobility of Daphnia observed in the test:

Initial concentration

(in mg of substance)

Immobilization

Number/20

%

24 hours

48 hours

24 hours

48 hours

Control

0

0

0

0

1.0

1

1

5

5

1.8

14

16

70

80

3.3

16

18

80

90

5.8

13

16

65

80

11

18

20

90

100

OECD Validity criteria:

-       Immobilization in the controls must not exceed 10% at the end of the test.

YES, immobilization in the control was zero.

-      Concentration of dissolved oxygen in the test vessels should remain above 3 mg l-1 throughout the course of the test.

YES, the dissolved oxygen concentrations were between 95 % and 97 % of the saturation value.

Additional EU quality criteria:

-       Test Daphnia in the control groups must not have been trapped at the surface of the water.

YES, test daphnia were not have been trapped at the surface of the water in the control groups. Daphnia were trapped at the surface of the water in all the test concentrations due to the formation of the substance clusters at the surface.

-       The concentration of the test substance shall be maintained to within 80% of the initial concentration throughout the duration of the test.

No data available

-       The initial concentration shall be taken as the concentration measured in solution (or, if technically not possible, measured in the water column) at the start of the test.

-       No data available

-       In any of these cases, further measurements must be made during the test to confirm the actual exposure concentrations or that the quality criteria have been met.

No data available

-       The pH should not vary by more than 1 unit.

No data available

Validity criteria fulfilled:
yes
Remarks:
Based on the OECD validity criteria
Conclusions:
On the basis of these results, it can be concluded that Rhodiastab X2 is classified as toxic to aquatic invertebrates in accordance with the classification system of the European Union.
Executive summary:

Rhodiastab X2 was tested for acute toxicity to Daphnia magna according to the EU method C2 (Acute toxicity for Daphnia), described in Annex V of the Directive 67/548/EEC, and in compliance with the Good Laboratory Practice.

Twenty daphnids, obtained from the laboratory breeding, were exposed to increased concentrations of the test substance, during 48 hours, in the dark at 20°C.

As the test substance is slightly soluble, it was heated at 30°C in a water-bath before being dissolved into the test medium and stirred to obtain the following nominal concentrations: 1 - 1.8 - 3.3 - 5.8 and 11 mg/L. The test solutions have been submitted to an ultra-sound treatment for one hour before being used for the daphnids test.

No significant immobilization was observed up to 1 mg/L and 100% immobilization was obtained with 11 mg/L. The EC50 was calculated to be the nominal concentration 1.9 mg/L.

Based on the results of this study, Rhodiastab X2 is considered as toxic to Daphnia magna in accordance with the classification system of the EU.

The results of this study should be used with caution because the substance formed an oily layer at the surface of the test solution which trapped some organisms. Hence, the real tested concentration could have been lower than the nominal ones and physical effect may have interfered the interpretation of the results.

Description of key information

Two studies are available to cover this endpoint.

One study has been performed with Rhodiastab X2 on Daphnia magna in an acute immobilization test following the EU method C2 (Acute toxicity for Daphnia), described in Annex V of the Directive 67/548/EEC, and in compliance with the Good Laboratory Practice.

Twenty daphnids were exposed to increased concentrations of the test substance during 48 hours, in the dark at 20°C. As the test substance is slightly soluble, it was heated at 30°C in a water-bath before being dissolved into the test medium and stirred to obtain the following nominal concentrations: 1 - 1.8 - 3.3 - 5.8 and 11 mg/L. The test solutions have been submitted to an ultra-sound treatment for one hour before being used for the daphnids test.

No significant immobilization was observed up to 1 mg/L and 100% immobilization was obtained with 11 mg/L. The EC50 was calculated to be the nominal concentration 1.9 mg/L.

Based on the results of this study, Rhodiastab X2 is considered as toxic to Daphnia magna in accordance with the classification system of the EU.

The results of this study should be used with caution because the substance formed an oily layer at the surface of the test solution which trapped some organisms. Hence, the real tested concentration could have been lower than the nominal ones and physical effect may have interfered the interpretation of the results.

Another study in accordance with the EC Guideline and GLP is available but only the commercial name is reported in the test report (i.e. no chemical name nor CAS RN). Moreover, the degree of purity is not available and the study reported an EC50 at 24h instead of 48h as requested by current guideline. For these reasons, this study was only supplied for information.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
1.9 mg/L

Additional information