Dimethylbis[(1-oxoneodecyl)oxy]stannane

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12 February 2018 to 25 April 2018

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:

2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- A single sample was taken from the control and each test group from the bulk test preparation at 0 hours and from the pooled replicates at 48 hours for quantitative analysis. All samples were stored frozen prior to analysis. A set of duplicate samples was also taken at 0 and 48 hours and stored frozen for further analysis if necessary.

Vehicle:

no

Details on test solutions:

- Preliminary solubility work indicated that the test material was practically insoluble in water using traditional methods of preparation e.g. ultrasonication and high shear mixing. A test concentration of 49 mg/L was obtained using a preliminary solution in reverse osmosis water.
- Based on this information the test material was categorised as being a ‘difficult substance’ as defined by the OECD Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures (OECD 2000). Therefore a media preparation trial was conducted in order to determine the solubility of the test material under test conditions.
- Based on this information the test material was prepared using a saturated solution method of preparation at an initial loading rate of 100 mg/L, stirred for a period of 24 hours prior to the removal of any undissolved test material by filtration through a 0.2 μm Sartorius Sartopore filter (first approximate 1 litre discarded) to give a nominal test concentration of approximately 49 mg/L.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Source: In house
- Age: Gravid adults were isolated the day before initiation of the test, such that the young daphnids produced overnight were less than 24 hours old. These young were removed from the cultures and used for testing.
- Feeding during test: No

CULTURE CONDITIONS
- Acclimation conditions: Adult daphnids were maintained in 150 mL glass beakers containing Elendt M7 medium in a temperature controlled room maintaining the water temperature at 18 to 22 °C. The lighting cycle was controlled to give a cycle of 16 hours of light and 8 hours of darkness with 20 minute dawn and dusk transition periods. Culture conditions ensured that reproduction was by parthenogenesis.
- Type and amount of food: Each culture was fed daily with a mixture of algal suspension (Desmodesmus subspicatus) and Tetramin® flake food suspension.
- Feeding frequency: Daily

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test temperature:

20 - 22 °C

pH:

7.8 - 8.1

Dissolved oxygen:

8.7 - 9.1 mg O2/L

Nominal and measured concentrations:

Nominal: 1.0, 3.2, 10, 32 and 100 mg/L
0 hours Measured: 0.771, 2.54, 8.10, 26.3 and 84.5 mg/L.
72 hours Measured: 0.854, 2.55, 8.20, 26.1 and 82.9 mg/L.

Details on test conditions:

TEST SYSTEM
- Test vessel: 150 mL glass beakers.
- Type: The test vessels were covered to reduce evaporation.
- Fill volume: 100 mL of test preparation.
- Aeration: No
- No. of organisms per vessel: 5
- No. of vessels per concentration: 4
- No. of vessels per control: 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water, ISO medium (main test), contained the following substances: CaCl2.2H2O (294 mg/L), MgSO4.7H2O (123 mg/L), NaHCO3 (65 mg/L), KCl (5.8 mg/L). The reconstituted water had a pH of 7.8 ± 0.2 adjusted (if necessary) with NaOH or HCl and was aerated until the dissolved oxygen concentration was approximately air saturation value.
The reconstituted water had an approximate theoretical total hardness of 250 mg/L as CaCO3.
- Water quality assessments: Water temperature was recorded daily throughout the test. Dissolved oxygen concentrations and pH were recorded at the start and termination of the test. The pH and dissolved oxygen concentration were measured using a Hach Flexi handheld meter whilst the temperature was measured using a Hanna Instruments HI 93510 digital thermometer. The light intensity during the light period was measured using an ATP Instrumentation Lux meter. The appearance of the test media was recorded daily.

OTHER TEST CONDITIONS
- Photoperiod: 16 hours of light and 8 hours of darkness with 20 minute dawn and dusk transition periods
- Light intensity: 200 to 1200 Lux

CONTROL PERFORMED: The control group was maintained under identical conditions but not exposed to the test material.

EFFECT PARAMETERS MEASURED:
Any immobilisation or adverse reactions to exposure were recorded at 24 and 48 hours after the start of exposure. The criterion of effect used was that daphnia were considered to be immobilised if they were unable to swim within 15 seconds after gentle agitation.

RANGE-FINDING STUDY
- Test concentrations: 0.10, 1.0, 10 and 100 % v/v saturated solution.
- Results used to determine the conditions for the definitive study: Yes. Based on the results of the range finding test the following test concentrations were assigned to the definitive test: 1.0, 3.2, 10, 32 and 100 % v/v saturated solution. An initial experiment was carried out in which > 10% immobilisation in the control daphnids was observed. This test therefore failed the validation criteria and was repeated.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

39 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

26 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

85 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

RANGE-FINDING TEST
- No immobilisation was observed at the test concentrations of 0.10 and 1.0 % v/v saturated solution; however, immobilisation was observed at 10 and 100 % v/v saturated solution.
- A sub lethal effect of exposure was observed at 100% v/v saturated solution. This response was trapping at surface.
- Based on this information test concentrations of 1.0, 3.2, 10, 32 and 100 % v/v saturated solution were selected for the definitive test.
- Chemical analysis of the test preparations at 0 hours showed measured test concentrations to range from 0.91 to 85 mg/L (85 to 91% of nominal values). There was no significant change in the measured concentrations at 48 hours indicating that the test material was stable under test conditions.

DEFINITIVE TEST
- Verification of Test Concentrations: Analysis of the test preparations at 0 hours showed measured test concentrations to range from 0.77 to 85 mg/L (between 77 and 85% of nominal values). There was no significant change in the measured concentrations at 48 hours and so the results are based on 0 hour measured test concentration.
- Immobilisation Data: Analysis of the immobilisation data at 24 and 48 hours by the binomial method and Probit analysis using Linear Maximum Likelihood regression respectively based on the 0 hour measured test concentrations gave the following results:
24 h EC50 = 47 mg/L (95 % Confidence limits 26 - 85 mg/L)
48 h EC50 = 39 mg/L (95 % Confidence limits could not be determined due to the nature of the data)
The NOEC after 24 and 48 hours exposure was 26 mg/L. The LOEC after 24 and 48 hours exposure was 85 mg/L. The slope and its standard error of the response curve at 48 hours was 1.1 (standard error = 0.16). Due to the nature of the data it was not possible to calculate the slope and error of response curve at 24 hours.
- Sub-Lethal Effects: No sub lethal effects of exposure were observed throughout the test.
- Validation Criteria: The test was considered to be valid given that none of the control daphnids showed immobilisation or other signs of disease or stress and that the oxygen concentration at the end of the test was equal to or greater than 3 mg/L in the control and test vessels.
- Water Quality Criteria: Temperature was maintained at 20°C to 22°C throughout the test, while there were no treatment related differences for oxygen concentration or pH. Throughout the test the light intensity was observed to be in the range 787 to 909 Lux.
- Observations on Test Material Solubility: At the start and throughout the test all control and test solutions were observed to be clear colourless solutions.

Results with reference substance (positive control):

- 24 Hours: EC50 = 0.61 mg/L, NOEC = 0.32 mg/L and LOEC = 0.56 mg/L
- 48 Hours: EC50 = 0.54 mg/L, NOEC = 0.56 mg/L and LOEC = 1.0 mg/L
- The No Observed Effect Concentration is based upon equal to or less than 10% immobilisation at this concentration.
- The results from the positive control with potassium dichromate were within the normal range for this reference item.

Reported statistics and error estimates:

The EC50 values and associated confidence limits at 24 and 48 hours and the slope of the response curve and its standard error at 48 hours were calculated by Binomial method and Probit Analysis using Linear Maximum Likelihood regression respectively. The Lowest Observed Effect Concentration and the NOEC at 24 and 48 hours were calculated using the Fisher’s Exact Binomial Test with Bonferroni correction and Step-down Cochran-Armitage Test respectively. All results were calculated using the ToxRat Professional computer software package (TOXRAT).

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of this study the 48 h EC50 was determined to be 39 mg/L. The NOEC after 24 and 48 hours exposure was 26 mg/L. The LOEC after 24 and 48 hours exposure was 85 mg/L.

Executive summary:

The toxicity of the test material to aquatic invertebrates was investigated in accordance with the standardised guidelines OECD 202 and EU Method C.2, under GLP conditions in an Acute Immobilisation Test.

Preliminary solubility work conducted indicated that it was not possible to obtain a testable solution of the test material using traditional methods of preparation e.g. ultrasonication and high shear mixing.

A preliminary media preparation trial indicated that a dissolved test material concentration of approximately 49 mg/L was obtained from a saturated solution method of preparation, indicating this to be the limit of water solubility of this material under test conditions.

Following a preliminary range finding test, 20 daphnids (4 replicates of 5 animals) were exposed to an aqueous solution of the test material at nominal concentrations of 1.0, 3.2, 10, 32 and 100 % v/v saturated solution for 48 hours at a temperature of 20°C to 22°C under static test conditions. The test material solutions were prepared by stirring an excess (100 mg/L) of test material in test water using a propeller stirrer at approximately 1500 rpm for 24 hours. After the stirring period any undissolved test material was removed by filtration (0.2 µm Sartorius Sartopore filter; first approximate 1 litre discarded in order to pre-condition the filter) to give a 100 % v/v saturated solution of the test material. This saturated solution was then further diluted as necessary, to provide the required test concentrations. Immobilisation and any adverse reactions to exposure were recorded after 24 and 48 hours.

Chemical analysis of the test preparations at 0 hours showed measured test concentrations which are based on tin concentrations to range from 0.77 to 85 mg/L (between 77 and 85% of nominal). There was no significant change in the measured concentrations at 48 hours and so the results are based on the 0 hour measured test concentrations.

Under the conditions of this study the 48 h EC50 was determined to be 39 mg/L. The NOEC after 24 and 48 hours exposure was 26 mg/L. The LOEC after 24 and 48 hours exposure was 85 mg/L.

Description of key information

Under the conditions of this study the 48 h EC50 was determined to be 39 mg/L. The NOEC after 24 and 48 hours exposure was 26 mg/L. The LOEC after 24 and 48 hours exposure was 85 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

39 mg/L

Additional information

The toxicity of the test material to aquatic invertebrates was investigated in accordance with the standardised guidelines OECD 202 and EU Method C.2, under GLP conditions in an Acute Immobilisation Test. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

Preliminary solubility work conducted indicated that it was not possible to obtain a testable solution of the test material using traditional methods of preparation e.g. ultrasonication and high shear mixing.

A preliminary media preparation trial indicated that a dissolved test material concentration of approximately 49 mg/L was obtained from a saturated solution method of preparation, indicating this to be the limit of water solubility of this material under test conditions.

Following a preliminary range finding test, 20 daphnids (4 replicates of 5 animals) were exposed to an aqueous solution of the test material at nominal concentrations of 1.0, 3.2, 10, 32 and 100 % v/v saturated solution for 48 hours at a temperature of 20°C to 22°C under static test conditions. The test material solutions were prepared by stirring an excess (100 mg/L) of test material in test water using a propeller stirrer at approximately 1500 rpm for 24 hours. After the stirring period any undissolved test material was removed by filtration (0.2 µm Sartorius Sartopore filter; first approximate 1 litre discarded in order to pre condition the filter) to give a 100 % v/v saturated solution of the test material. This saturated solution was then further diluted as necessary, to provide the required test concentrations. Immobilisation and any adverse reactions to exposure were recorded after 24 and 48 hours.

Chemical analysis of the test preparations at 0 hours showed measured test concentrations which are based on tin concentrations to range from 0.77 to 85 mg/L (between 77 and 85 % of nominal). There was no significant change in the measured concentrations at 48 hours and so the results are based on the 0 Hour measured test concentrations.

Under the conditions of this study the 48 h EC50 was determined to be 39 mg/L. The NOEC after 24 and 48 hours exposure was 26 mg/L. The LOEC after 24 and 48 hours exposure was 85 mg/L.