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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:
04-May-2010 to 11-May-2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose:
other: analytical methods
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
GLP compliance:
yes (incl. certificate)
Remarks:
swissmedic: Date of inspection: 05 to 09-Nov-2007 and 26 to 30-Nov-2007; Date of decision: 2008-04-30, Date of signature: 12-Nov-2008
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
not applicable
Analytical monitoring:
yes
Details on sampling:
For the determination of the actual test item concentration, duplicate samples were taken from the test medium of the single test concentration before test start and at the end of the test after 48 hours. Duplicate samples were also taken from the control. For the 48-hour stability samples, the contents of the respective replicates were combined prior to sampling.

All samples were stored deep-frozen (at about -20 °C) immediately after sampling. Based on a pre-experiment (non-GLP), the test item proved to be sufficiently stable in the test water under these storage conditions.

The concentration of the test item Sodiumtrimetaphosphate was analytically measured in the duplicate test medium samples of the single test concentration taken at the start and the end of the test.

From the control, only one of the duplicate samples was analyzed per sampling time.

The analytical procedure and results are described in the the attached "APPENDIX I – ANALYTICAL INVESTIGATIONS" .
Vehicle:
no
Details on test solutions:
The test medium was prepared by dissolving 30.09 mg of test item completely in 300 mL of test water under intense stirring for 15 minutes at room temperature. The test medium was prepared just before introduction of the daphnids (i.e., start of the test).
Test organisms (species):
Daphnia magna
Details on test organisms:
The study was performed with young daphnids of the species Daphnia magna Straus. A clone of this species (defined by the supplier as clone 5) was originally supplied by the University of Sheffield / UK in 1992. Since that time, the clone has been bred at Harlan Laboratories in reconstituted water of the quality identical to the water quality used in the tests (in respect to pH, main ions, and total hardness) and under temperature and light conditions identical to those of the tests.

During breeding, daphnids are generally fed three times a week with an algal suspension of the green algae Desmodesmus subspicatus CHODAT, Strain No. 86.81 SAG, supplied by the Collection of Algal Cultures (SAG, Institute for Plant Physiology, University of Göttingen, 37073 Göttingen / Germany) and cultivated at Harlan Laboratories under standardized conditions or a mixture of this algal suspension and a commercial fish diet (Tetra Min® Hauptfutter, supplied by TETRA-Werke, 49304 Melle / Germany).

At the start of the test, the organisms used in the test were 6 to 24 hours old and were not first brood progeny.

For evaluation of the quality of the daphnia clone and the experimental conditions, potassium dichromate is tested as a positive control twice a year. The result of the latest positive control test in March 2010 (48-hour EC50: 0.43 mg/L, study C86933) proved the sensitivity of the test organisms and the validity of the test design (internal historical range of 48-hour EC50 from 2000 to 2010: 0.43 to 1.1 mg/L).

The test method and the test species are recommended by the international test guidelines.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Post exposure observation period:
not applicable
Hardness:
2.5 mmol/L
Test temperature:
The water temperature during the test was maintained at 20 °C
pH:
The pH values of the test medium and control were between 7.8 and 8.0
Dissolved oxygen:
at least 6.9 mg/L
Salinity:
according to ISO 6341
Nominal and measured concentrations:
A limit test was performed in accordance with the test guidelines to demonstrate that the test item Sodiumtrimethaphosphate has no toxic effect on Daphnia magna at a nominal concentration of 100 mg/L.

The analytically determined concentration of the test item in the test medium at the start and at the end of the test was 85 and 96% of the nominal value, respectively. Thus, the correct dosing of the test item Sodiumtrimetaphosphate at test start was confirmed. Furthermore, it has been demonstrated that the test item was sufficiently stable during the test period of 48 hours under the conditions of the test, and the reported biological results are based on the nominal concentrations of the test item.

Dosage
The test medium was prepared by dissolving 30.09 mg of test item completely in 300 mL of test water under intense stirring for 15 minutes at room temperature. The test medium was prepared just before introduction of the daphnids (i.e., start of the test).
Details on test conditions:
For details about the test water please see section - any other information on materials and methods incl. tables.

The test water was aerated prior to the start of the study until oxygen saturation was reached. During the test period, the test water was not aerated.

The test was performed in 100 mL glass beakers filled with 50 mL of test medium. The test vessels were covered with glass plates to reduce the loss of water by evaporation and to avoid the entry of dust into the solutions.

The test vessels were labeled with the study number and all necessary additional information to ensure unique identification.

The test was performed in a temperature-controlled room with continuous monitoring of the room temperature. The water temperature was maintained at 20 °C.

A 16-hour light to 8-hour dark cycle with a 30-minute transition period was used. Light intensity during the light period was approximately between 520 and 680 Lux.

The daphnids were not fed during the test.

Reference substance (positive control):
yes
Remarks:
potassium dichromate, tested twice a year
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 100
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: immobility
Remarks on result:
other: 95% CL not reported
Details on results:
A limit test was performed in accordance with the test guidelines to demonstrate that the test item Sodiumtrimethaphosphate has no toxic effect on Daphnia magna at a nominal concentration of 100 mg/L.

The analytically determined concentration of the test item in the test medium at the start and at the end of the test was 85 and 96% of the nominal value, respectively. Thus, the correct dosing of the test item Sodiumtrimetaphosphate at test start was confirmed. Furthermore, it has been demonstrated that the test item was sufficiently stable during the test period of 48 hours under the conditions of the test, and the reported biological results are based on the nominal concentrations of the test item.

In the control and at the test concentration of 100 mg/L, no immobilized test organisms were observed during the test period of 48 hours.

Therefore, the 48 hour NOEC and 48-hour EC0 of Sodiumtrimetaphosphate to Daphnia magna were determined to be at least 100 mg/L. The 48-hour NOEC and 48-hour EC0 might even be higher, but concentrations above 100 mg/L were not tested, in accordance with the test guidelines. The 48-hour EC50 and the 48-hour EC100 were clearly higher than 100 mg/L. These values could not be quantified due to the absence of a toxic effect of Sodiumtrimetaphosphate at the test concentration of 100 mg/L.

No remarkable observations were made concerning the appearance of the test medium. The test medium was a clear solution throughout the whole test duration.

At the beginning and at the end of the test period, the dissolved oxygen concentration in the test medium and control was at least 6.9 mg/L. The pH values of the test medium and control were between 7.8 and 8.0. The water temperature during the test was maintained at 20 °C (Table 2).

The test is considered to be valid, as in the control no daphnids showed immobilization or other signs of disease or stress (e.g., discoloration or unusual behavior such as trapping at the surface water) was fulfilled. Furthermore, the dissolved oxygen concentration at the end of the test was ≥3 mg/L in the control and test vessels.

Results with reference substance (positive control):
For evaluation of the quality of the daphnia clone and the experimental conditions, potassium dichromate is tested as a positive control twice a year. The result of the latest positive control test in March 2010 (48-hour EC50: 0.43 mg/L, study C86933) proved the sensitivity of the test organisms and the validity of the test design (internal historical range of 48-hour EC50 from 2000 to 2010: 0.43 to 1.1 mg/L).
Reported statistics and error estimates:
The daphnids were observed for immobility after 24 and 48 hours of exposure (daphnids not being able to swim within 15 seconds after gentle agitation of the test beaker are considered to be immobilized).

The NOEC and EC0 were determined directly from the raw data. The EC50 and the EC100 could not be calculated due to the absence of a toxic effect of the test item in this test.

Please see attached Tables Table 1 Effect of Sodiumtrimetaphosphate on the Mobility of Daphnia magna & Table 2 Dissolved Oxygen Concentrations, pH Values and Temperature in the Treatments.

Validity criteria fulfilled:
yes
Conclusions:
The test item Sodiumtrimetaphosphate has no acute toxic effect on Daphnia magna up to a concentration of 100 mg/L under the present test conditions.
This study is conducted according to the appropriate guidelines (EU ) and under the conditions of GLP and therefore the study is considered to be acceptable and to adequately satisfy both the guideline requirement and the regulatory requirement as a key study for this endpoint. Study is sufficient for classification and labelling purposes, in accordance with Regulation (EC) No. 1272/2008 (EU CLP).
Executive summary:

A limit test was performed in accordance with the test guidelines to demonstrate that the test item Sodiumtrimetaphosphate has no toxic effect on the test organisms up to and including a nominal concentration of 100 mg/L. Thus, the only nominal concentration tested was 100 mg/L. Additionally, a control (test water without test item)was tested in parallel.

 

The analytically determined concentration of the test item in the test medium at the start and at the end of the test was 85 and 96% of the nominal value, respectively. Thus, the test item Sodiumtrimetaphosphate proved to be stable during the test period of 48 hours under the conditions of the test. Therefore, all reported results are related to the nominal concentration of the test item.

 

In the control and at the test item concentration of 100 mg/L, no immobilized test organisms were observed during the test period of 48 hours. Therefore, the 48-hour NOEC and 48-hour EC0of Sodiumtrimetaphosphate toDaphnia magnawere determined to be at least 100 mg/L. The 48-hour NOEC and 48-hour EC0might even be higher, but concentrations above 100 mg/L were not tested, in accordance with the test guidelines. The 48-hour EC50and the 48-hour EC100were clearly higher than 100 mg/L. These values could not be quantified due to the absence of a toxic effect of Sodiumtrimetaphosphate at the test concentration of 100 mg/L.

 

Thus, it can be concluded that the test item Sodiumtrimetaphosphate has no acute toxic effect on Daphnia magna up to a concentration of 100 mg/L under the present test conditions.

Description of key information

One key study exists. This study had been conducted in accordance with a recommended guideline (OECD 202, EU Method C.2) and under the conditions of GLP. As such, no further testing is considered necessary.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
100 mg/L

Additional information

On the basis of a limit test, the EC50 of trisodium trimetaphosphate has been determined to be >100 mg/l.