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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:
other: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
From February 22 to June 03, 1994
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
The test was conducted by means of Read Across approach. The reliability of the source study report is 1. Further information was attached at section 13
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
Qualifier:
according to
Guideline:
other: EEC Directive 84/449, L 251, Part C 2
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations:
NOMINAL
1.0/1.8/3.2/5.8/10/18/32/58 and 100 mg test article /l
MEASURED AT START
1.5/0.3/0.9/3.4/8.2/4.4/4.7/11.4/28.2 mg test article /l
MEASURED AT END
1.0/2.2/2.7/5.4/11.8/6.5/6.2/13.0/28.2 mg test article /l
- Sampling method: All test medium samples for the analytical determinations were taken from the approximate center of the test vessels (without mixing the medium); the concentrations of the test substance at the beginning and at the end of the test was analysed by spectrophotometry (459nm).
- Sample storage conditions before analysis: kept at -18°C to -25°C until analyses
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: 0.5 g test substance were mixed with 200 ml test medium and fill up to 500 ml with test medium. The stock solution was homogenized for 20 minutes in the ultrasonics bath.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Strain: Daphnia magna
- Source: bred in the testing facility of the Product Ecology TF, Textile Dyes Division under standardised conditions
- Method of breeding: Cultures of Daphnia magna are maintained in glass vessels containing aprox. 3.0 l of reconstituted water at 18 - 22°C. The water was renewed partially three times weekly. The Daphnia were feed with a suspension of green algae (Scenedesmus subspicatus) supplemented by a suspension of TETRAMIN-extract in such quantites that the food was consumed within 24h
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
136 mg/l CaCO3
Test temperature:
21 ± 1 °C measured at the beginning and at the end of the test
pH:
7.8 - 8.2
Dissolved oxygen:
98 - 99 %
Nominal and measured concentrations:
NOMINAL
1.0/1.8/3.2/5.8/10/18/32/58 and 100 mg test article /l
MEASURED AT START
1.5/0.3/0.9/3.4/8.2/4.4/4.7/11.4/28.2 mg test article /l
MEASURED AT END
1.0/2.2/2.7/5.4/11.8/6.5/6.2/13.0/28.2 mg test article /l
Details on test conditions:
TEST SYSTEM
- Test vessel: 250ml beakers
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: bidistilled water with these components:
NaHCO3 65 mg/l
MgSO4 x 7 H20 123.3 mg/l
KCI 5.8 mg/l
CaCI2 x 2 H20 294 mg/l
Na2SiO3 x 9 H20 10 mg/l
NaNO3 274 µg/l
KH2PO4 143 µg/l
K2HPO4 184 µg/l
- Alkalinity: 0.8 mmol/l
- Ca/mg ratio: 4:1
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Photoperiod: 16 hours light/8 hours dark

TEST CONCENTRATIONS
- Spacing factor for test concentrations: ca. 1.8
- Test concentrations: 1.0/1.8/3.2/5.8/10/18/32/58 and 100 mg test article /l (nominal)
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Duration:
24 h
Dose descriptor:
EC0
Effect conc.:
>= 1.3 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: actual concentration measured by analytical analysis
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
ca. 5 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: The EC50 value are calculated with the " Probit model " method; CL 95%: 3.78 - 6.51
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
ca. 4 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: EC50 value graphically determined.
Duration:
24 h
Dose descriptor:
EC100
Effect conc.:
> 28.2 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: actual concentration measured by analytical analysis
Duration:
48 h
Dose descriptor:
EC0
Effect conc.:
>= 1.3 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: actual concentration measured by analytical analysis
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
ca. 2.3 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: The EC50 value are calculated with the " Probit model " method; CL 95%: 1.83 - 2.71
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
ca. 1.6 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: EC50 value graphically determined.
Duration:
48 h
Dose descriptor:
EC100
Effect conc.:
ca. 12.2 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: actual concentration measured by analytical analysis
Details on results:
- Mortality of control: in the control no immobilization of the Daphnia was observed.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: in the test concentrations from nominal 18 mg/l up to 100 mg/l a sedimentation in the test beakers was observed after 48 hours.
Results with reference substance (positive control):
- Results with reference substance valid: according to the results of the inter laboratory tests and a Technical Corrigendum to ISO 6341 give an EC50-24 h of the potassium dichromate (K2Cr2O7) within the range 0.6 mg/l to 2.1 mg/l. - Reference: OECD guideline 202.
- EC50: 1.01 mg/l
The quality of the Daphnia was checked at least every 3 months by determining the EC50 values (24 h) for potassium dichromate.
Validity criteria fulfilled:
yes
Conclusions:
EC50 (48h) = 2.3 mg/l
Executive summary:

Method

The test has been conducted in agreement with OECD guideline 202 and EEC Directive 84/449, L 251, Part C 2.

The test was performed in compliance with the Good Laboratory Practice Regulations.

The substance was tested for its acute toxicity to Daphnia magna in a 48 hours static test. 24 hours before the start of the exposure reproductive Daphnia were separated from the young Daphnia by sieving all individuals through a 710 µm sieve. For each concentration, of test substance, 20 Daphnia divided in two groups of 10 animals were used.

The Daphnia were exposed to the test article in 250 ml beakers containing 100 - 200 ml test medium with 10 animals per beaker. During exposure the animals were kept at 21 ± 1 °C with 16 hours illumination. The oxygen concentration, the pH and the temperature were controlled at the beginning and at the end of the test.

Based on a pretest, the test concentrations were chosen as 1.0/1.8/3.2/5.8/10/18/32/58 and 100 mg test article/l (nominal).

All test medium samples for the analytical determinations were taken from the approximate center of the test vessels (without mixing the medium) and kept at -18 °C to -25 °C until analysis.

Test evaluations were done according to the guidelines by visual assessment of mobility of the Daphnia after 24 and 48 hours.

Results

The EC50 was determined in two ways:

- graphically: EC50 4 mg/l (24h); EC50 1.6 mg/l (48h)

- statistically (probit): EC50 5 mg/l (24h); EC50 2.3 mg/l (48h)

Description of key information

EC50 = 2.3 mg/l.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
2.3 mg/L

Additional information

No studies conducted on the substance in itself are available, nevertheless studies conducted with an analogue molecule (Similar Substance 01) were considered to complete the assessment. Further information are reported in the Read Across justification attached to section 13.

In order to determine the short-term toxicity to aquatic invertebrates, the substance under registration was tested on Daphnia sp. according to OECD Guideline 202. The concentrations tested were: 1.5/0.3/0.9/3.4/8.2/4.4/4.7/11.4/28.2 mg test article /l based on analytical results. The nominal concentrations were 1.0/1.8/3.2/5.8/10/18/32/58 and 100 mg test article /l.

The EC50 was determined in two ways: graphically, interpolating the point plotted on a graph; and statistically, calculating with the "probit model" method. The EC50 at 48 hours were 1.6 and 2.3 mg/l respectively. The EC50 value obtained statistically has been used as reference due to the more reliability of the method.