9-[2-(2-methoxyethoxy)ethoxy]-9-[3-(oxiranylmethoxy)propyl]-2,5,8,10,13,16-hexaoxa-9-silaheptadecane

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:

This study was conducted between 02 August 2016 and 23 September 2016

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:

April 2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

EC No 440/2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Range-Finding Test:
A nominal amount of test item (50 mg) was dissolved in test water and the volume adjusted to 500 mL to give the 100 mg/L test concentration from which a series of dilutions was made to give further test concentrations of 10, 1.0 and 0.10 mg/L.
Each prepared concentration was inverted several times to ensure adequate mixing and homogeneity.
A sample of each test concentration was taken for chemical analysis at 0 and 48 hours in order to determine the stability of the test item under test conditions. All samples were stored frozen prior to analysis. Only concentrations within the range to be used for the definitive test were analyzed.

Definitive Test:
Based on the results of the range-finding test, the following test concentrations were assigned to the definitive test: 6.25, 12.5, 25, 50 and 100 mg/L
Each prepared concentration was inverted several times to ensure adequate mixing and homogeneity.
The concentration and stability of the test item in the test preparations were verified by chemical analysis at 0, 24 and 48 hours.

Vehicle:

no

Details on test solutions:

Range-Finding Test:
A nominal amount of test item (50 mg) was dissolved in test water and the volume adjusted to 500 mL to give the 100 mg/L test concentration from which a series of dilutions was made to give further test concentrations of 10, 1.0 and 0.10 mg/L.
Each prepared concentration was inverted several times to ensure adequate mixing and homogeneity.

Definitive Test:
A nominal amount of test item (200 mg) was dissolved in test water and the volume adjusted to 2 liters to give the 100 mg/L test concentration from which a series of dilutions was made to give further test concentrations of 50, 25, 12.5 and 6.25 mg/L.
Each prepared concentration was inverted several times to ensure adequate mixing and homogeneity.

Test organisms (species):

Daphnia magna

Details on test organisms:

The test was carried out using 1st instar Daphnia magna derived from in-house laboratory cultures.
Adult daphnia were maintained in 150 mL glass beakers containing Elendt M7 medium (see Annex 1) in a temperature controlled room maintaining the water temperature at 18 to 22 °C. The lighting cycle was controlled to give a 16 hours light and 8 hours darkness cycle with 20 minute dawn and dusk transition periods. Each culture was fed daily with a mixture of algal suspension (Desmodesmus subspicatus) and Tetramin® flake food suspension. Culture conditions ensured that reproduction was by parthenogenesis. 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. The diet and diluent water are considered not to contain any contaminant that would affect the integrity or outcome of the study.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Remarks on exposure duration:

Exposure at 18 °C to 22 °C with a maximum deviation of ± 1 °C with a photoperiod of 16 hours light (between 200 and 1200 Lux) and 8 hours darkness with 20 minute dawn and dusk transition periods

Post exposure observation period:

None

Hardness:

Not reported

Test temperature:

18 - 22”C

pH:

7.8 - 7.9

Dissolved oxygen:

Not reported

Salinity:

Not reported

Conductivity:

Not reported

Nominal and measured concentrations:

Analysis of the fresh test preparations at 0 hours showed measured test concentrations to range from 15% to 46% of nominal concentrations. Analysis of the fresh test preparations at 24 hours showed measured test concentrations to range from 46% to 67% of the nominal concentrations.
Given the low measured concentrations obtained in the freshly prepared media and the unstable nature of the test item in solution, it was considered appropriate to estimate the results based on the average geometric mean measured test concentrations

Details on test conditions:

Range-Finding Test:
In the range-finding test, 10 daphnids were placed in each test and control vessel, and maintained in a temperature controlled room maintaining the water temperature at 18 °C to 22 °C with a maximum deviation of ± 1 °C with a photoperiod of 16 hours light and 8 hours darkness for a period of 48 hours with 20 minute dawn and dusk transition periods. Each 150 mL test and control vessel contained 100 mL of test media and was covered to reduce evaporation. After 24 and 48 hours the number of immobilized daphnids was recorded.
The control group was maintained under identical conditions, but not exposed to the test item.#

Definitive Test:
As in the range-finding test, 150 mL glass jars containing approximately 100 mL of test preparation were used. At the start of the test, 5 daphnids were placed in each test and control vessel at random, in the test preparations. Four replicate test and control vessels were prepared. The test vessels were then covered to reduce evaporation and maintained in a temperature controlled room maintaining the water temperature at 18 °C to 22 °C with a maximum deviation of ± 1 °C with a photoperiod of 16 hours light (between 200 and 1200 Lux) and 8 hours darkness with 20 minute dawn and dusk transition periods. The daphnids were not individually identified, received no food during exposure and the test vessels were not aerated.
The control group was maintained under identical conditions, but not exposed to the test item.
Semi-static test conditions were employed in the test in an effort to maintain dissolved test item concentrations. For the test media renewal at 24 hours, the test concentrations were freshly prepared and the daphnids transferred by wide bore pipette from the 24-Hour old test media into the fresh test media.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 10 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

ca. 10 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

Range-Finding Test:
No immobilization was observed in the 1.0 mg/L test concentrations, however, immobilization was observed at 0.10, 10 and 100 mg/L.
Based on this information test concentrations of 6.25, 12.5, 25, 50 and 100 mg/L were selected for the definitive test.

Definitive Test:
Immobilization Data
There was no immobilization in 20 daphnids exposed to the average geometric mean measured test concentrations of 1.1, 2.0, 5.1 and 10 mg/L for a period of 48 hours. A single daphnid was immobilized in the 0.83 mg/L test concentration, but this was considered to be unrelated to exposure to the test item.

Sub-Lethal Effects
Sub-lethal effects of exposure were observed in the 1.1, 2.0 and 5.1 mg/L test concentrations. These responses were reduced mobility and trapping at the surface.

Validation Criteria
The test was considered to be valid given that none of the control daphnids showed immobilization or other signs of disease or stress, and that the oxygen concentration at the end of the test was greater than 3 mg/L in the control and test vessels.

Water Quality Criteria
Temperature was maintained at 21”C to 23”C throughout the test, while there were no treatment related differences for oxygen concentration or pH.
The temperature in the 12.5 mg/L test solution at 0 hours was measured to be slightly in excess of the 18 C to 22 °C range given in the study plan. This was considered not to affect the results of the test as it was within range at subsequent measurements and the temperatures did not deviate more than ± 1 °C throughout the test.

Throughout the test the light intensity was observed to be in the range 526 to 682 Lux.

Observations on Test Item Solubility
At the start and throughout the test, all control and test solutions were observed to be clear colorless solutions.

Results with reference substance (positive control):

Positive Control
A positive control (Envigo Study Number MS29MC) used potassium dichromate as the reference item at concentrations of 0.32, 0.56, 1.0, 1.8 and 3.2 mg/L.
Exposure conditions for the positive control were similar to those in the definitive test.
Analysis of the immobilization data by the probit analysis using the linear maximum likelihood regression method at 24 and 48 hours using the ToxRat Professional computer software package based on the nominal test concentrations gave the following results:

Time Point (Hours) EC50 (mg/L) 95% Confidence Limits (mg/L) No Observed Effect Concentration (NOEC) (mg/L) Lowest Observed Effect Concentration (LOEC) (mg/L)
24 0.83 0.70-0.98 0.56 1.0
48 0.64 Not possible to determine 0.56 1.0

The No Observed Effect Concentration is based upon equal to or less than 10% immobilization at this concentration.
The results from the positive control with potassium dichromate were within the normal range for this reference item.

Validity criteria fulfilled:

yes

Conclusions:

The acute toxicity of the test item to the freshwater invertebrate Daphnia magna has been investigated and gave a 48-Hour EC50 value of greater than 10 mg/L based on the average geometric mean measured test concentrations. The No Observed Effect Concentration was 10 mg/L.

Executive summary:

A study was performed to assess the acute toxicity of the test item to Daphnia magna.  The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (April 2004) No. 202, "Daphnia sp., Acute Immobilisation Test" referenced as Method C.2 of Commission Regulation (EC) No. 440/2008.

Methods

Following a preliminiary range-finding test, twenty daphnids (4 replicates of 5 animals) were exposed to an aqueous solution of the test item at nominal concentrations of 6.25, 12.5, 25, 50 and 100 mg/L for 48 hours at a temperature of 21 to 23 deg C under semi-static test conditions.  The number of immobilized daphnia was recorded after 24 and 48 hours.

Results

Analysis of the fresh test preparations at 0 hours (see Annex 4) showed measured test concentrations to range from 15% to 46% of nominal concentrations.  Analysis of the fresh test preparations at 24 hours showed measured test concentrations to range from 46% to 67% of the nominal concentrations.

Analysis of the aged test preparations at 24 and 48 hours showed measured test concentrations to range from less than the limit of quantification (LOQ) of the analytical method employed, which was determined to be 0.53 mg/L, to 2% of nominal.

Given this decline in measured test concentrations it was considered justifiable to base the results on the average geometric mean measured test concentrations in order to give a "worst case" analysis of the data.

Exposure of Daphnia magna to the test item gave a 48-Hour EC50 value of greater than 10 mg/L based on the geometric mean test measured concentrations.  The No Observed Effect Concentration was 10 mg/L.

Description of key information

A study was performed to assess the acute toxicity of the test item to Daphnia magna.  The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (April 2004) No. 202, "Daphnia sp., Acute Immobilisation Test" referenced as Method C.2 of Commission Regulation (EC) No. 440/2008.

Methods

Following a preliminiary range-finding test, twenty daphnids (4 replicates of 5 animals) were exposed to an aqueous solution of the test item at nominal concentrations of 6.25, 12.5, 25, 50 and 100 mg/L for 48 hours at a temperature of 21 to 23 °C under semi-static test conditions.  The number of immobilized daphnia was recorded after 24 and 48 hours.

Results

Analysis of the fresh test preparations at 0 hours (see Annex 4) showed measured test concentrations to range from 15% to 46% of nominal concentrations.  Analysis of the fresh test preparations at 24 hours showed measured test concentrations to range from 46% to 67% of the nominal concentrations.

Analysis of the aged test preparations at 24 and 48 hours showed measured test concentrations to range from less than the limit of quantification (LOQ) of the analytical method employed, which was determined to be 0.53 mg/L, to 2% of nominal.

Given this decline in measured test concentrations it was considered justifiable to base the results on the average geometric mean measured test concentrations in order to give a "worst case" analysis of the data. Exposure of Daphnia magna to the test item gave a 48-Hour EC50 value of greater than 10 mg/L based on the geometric mean test measured concentrations.  The No Observed Effect Concentration was 10 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

10 mg/L