1,1,3,3-tetramethyl-1,3-divinyldisiloxane

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:

24th July to 19th September 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study was conducted according to the appropriate OECD test guideline, and in compliance with GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: nominal: 0.013, 0.026, 0.053, 0.11 and 0.21 mg/L

- Sampling method: Water samples were taken at 0 and 48 hours. The test samples were analyzed on the day of receipt.

- Sample storage conditions before analysis: Duplicate samples were taken and stored at approximately -20 °C for further analysis if necessary.

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A solvent stock solution of the test item was prepared at a concentration of 1000 mg/100 mL in order to ensure that the maximum attainable dissolved test item concentration was obtained. Environmental measurements were not performed at 24 hours in order to limit the loss of test item through volatilization.
The test item solutions were prepared by initially dissolving 1000 mg of test item in a final volume of 100 mL of dimethylformamide. Aliquots (130, 260 and 530 µL, 1.1 and 2.1 mL) of this initial stock solution were each separately added to a final volume of 10 mL of dimethylformamide to give the further solvent stock solutions of 1.3, 2.6, 5.3, 11 and 21 mg/ 10 mL. An aliquot (50 µL) of the 1.3, 2.6, 5.3, 11 and 21 mg/ 10 mL solvent stock solutions were then each separately dispersed in a final volume of 500 mL of Elendt M7 to give the 0.013, 0.026, 0.053, 0.11 and 0.21 mg/L test concentrations.
Each solvent stock solution and each prepared concentration was inverted several times to ensure adequate mixing and homogeneity.

- Controls: Test water only and solvent control of test water with 100 µL/L of dimethylformamide.

- Chemical name of vehicle (organic solvent, emulsifier or dispersant): dimethylformamide

- Concentration of vehicle in test medium (stock solution and final test solution):

- Evidence of undissolved material (e.g. precipitate, surface film, etc): Test preparations observed to be clear, colourless solutions for the duration of the test.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna

- Strain: 1st instar

- Source: In-house laboratory cultures

- Age at study initiation (mean and range, SD): maximum of 26 hours

- Method of breeding: parthenogenesis

- Feeding during test: None

ACCLIMATION
- Acclimation period: Culture conditions: Adult Daphnia were maintained in 150 mL glass beakers containing Elendt M7 medium in a temperature controlled room at approximately 20 °C with 16 hours light and 8 hours darkness cycle with 20 minute dawn and dusk transition periods

- Acclimation conditions (same as test or not): Test conditions at room temperature of 21 °C with the same lighting cycle

- Type and amount of food: algal suspension (Desmodesmus subspicatus) and Tetramin® flake food suspension

- Feeding frequency: Daily

- Health during acclimation (any mortality observed): Not specified

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

Not recorded

Test temperature:

21 °C

pH:

Range 7.9 - 8.1

Dissolved oxygen:

Range 8.5 - 9.0 mg O2/L

Salinity:

Freshwater

Nominal and measured concentrations:

Nominal: 0.013, 0.026, 0.053, 0.11 and 0.21 mg/L
Measured: 0 hrs: 0.00616, 0.0159, 0.0344, 0.0111 / 0.0116*, 0.163 mg/L (* Duplicate sample stored at approximately -20 °C prior to analysis.)
48 hrs: 0.00204, 0.00753, 0.0147, 0.00485, 0.0616 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Conical flask

- Type (delete if not applicable): closed: glass stoppered and sealed

- Material, size, headspace, fill volume: 100 ml, filled with 100 ml test preparation

- Aeration: None

- Type of flow-through (e.g. peristaltic or proportional diluter): No flow-through

- Renewal rate of test solution (frequency/flow rate): No renewal

- No. of organisms per vessel: 10

- No. of vessels per concentration (replicates): 1

- No. of vessels per control (replicates): 1

- Biomass loading rate: Not specified

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water: Elendt M7 Medium

- Culture medium different from test medium: No

- Intervals of water quality measurement: 0 and 48 hours

OTHER TEST CONDITIONS
- Adjustment of pH: No

- Photoperiod: 16 hours light and 8 hours darkness with 20 minute dawn and dusk transition periods

- Light intensity: 634 to 668 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Immobilization at 24 and 48 hrs

TEST CONCENTRATIONS
- Spacing factor for test concentrations: approximately 2

- Range finding study: Several initial range-finding tests were performed using various methods of preparation.

- Test concentrations: Not specified

- Results used to determine the conditions for the definitive study: analysis of the initial test preparations showed inconsistent results were obtained, possibly due to the volatile nature of the test item. It was therefore considered appropriate to prepare a solvent stock solution of the test item at a concentration of 1000 mg/100 mL in order to ensure that the maximum attainable dissolved test item concentration was obtained. Furthermore, it was decided that environmental measurements would not be performed at 24 hours in order to limit the loss of test item through volatilization.

Reference substance (positive control):

yes

Remarks:

potassium dicromate

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 0.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 0.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

0.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: None specified

- Observations on body length and weight: Not observed

- Other biological observations: None specified

- Mortality of control: Single immobilized daphnids were observed in the control

- Other adverse effects control: None specified

- Abnormal responses: None specified

- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: A decline in measured concentration was observed in the old media at 48-hours. This decline was considered to be due to the unstable nature of the test item and/or losses through volatilization.

- Effect concentrations exceeding solubility of substance in test medium:

Results with reference substance (positive control):

- Results with reference substance valid? Yes

- Mortality: Not specified

- EC50: 24 h 0.75 mg/L, 48 h 0.45 mg/L

- Other: 95% CL mg/L: 24 h 0.56 - 1.0, 48 h 0.42 - 0.48
NOEC: 24 h 0.56 mg/L, 48 h 0.32 mg/L

Table 1: Results for Test Samples: Measured Concentrations

Time Point (hours)	Nominal Concentration of Test Item in Test Sample (mg/L)	Determined Concentration of Test Item in Test Sample (mg/L)	% of Nominal Concentration (%)
0 (fresh)	0.013	0.00616	47
	0.026	0.0159	61
	0.053	0.0344	65
	0.11	0.0111/0.0116 *	10/11*
	0.21	0.163	78
48 (old)	0.013	0.00204	16
	0.026	0.00753	29
	0.053	0.0147	28
	0.11	0.00485	4
	0.21	0.0616	29

Table 2. Geometric Mean Measured Concentrations

Nominal Concentration (mg/L)	Geometric Mean Measured Concentration (mg/L)	Expressed as a Percentage of the Nominal Concentration (%)
0.013	0.0035	27
0.026	0.011	42
0.053	0.023	42
0.11	0.0075	7
0.21	0.10	48

Table 3. Cumulative Immobilisation Data in the Range-finding Test

Geometric Mean Measured Concentration (mg/L)	Cumulative Immobilized Daphnia (Initial Population: 10 per Replicate)
	24 hours	48 hours
Control	0	1
Solvent Control	0	0
0.0035	0	0
0.011	0	0
0.022	0	1
0.0075	0	1
0.10	0	0

Validity criteria fulfilled:

yes

Remarks:

No more than 10% control immobilization and >= 3 mg/L dissolved oxygen in control and test vessels after 48 h

Conclusions:

A 48-h EC50 value of >0.10 mg/L and a NOEC of 0.10 mg/L have been determined for the effects of the test substance on mobility of Daphnia magna based on geometric mean concentrations.

Description of key information

Short-term toxicity to invertebrates: 48-h EC₅₀ >0.1 mg/l (measured) (highest concentration tested) (OECD guideline 202)

Additional information

A 48 hour EC₅₀ value of >0.1 mg/l (geometric mean measured concentration) (highest concentration tested) has been determined for the effects of the registration substance on mobility of Daphnia magna (Harlan laboratories, 2013). In view of the test media preparation method/exposure regime it is likely that the test organisms were exposed predominantly to the tested substance. Effectively these results indicate no effects at the limit of achievable solubility in test medium.  

.