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

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23rd April to 6th December 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 211 (Daphnia magna Reproduction Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.20 (Daphnia magna Reproduction Test)

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 of the fresh test preparations were taken on Days 0, 5, 8, 12, 15 and 20 and of the expired test preparations on Days 1, 6, 9, 13, 16 and 21. Duplicate samples were taken and stored at approximately -20 °C for further analysis if necessary.

- Sample storage conditions before analysis: The samples were analyzed on the day of receipt

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: For the purpose of the test, the test item was prepared using a preliminary solution in dimethylformamide.

An amount of test item (1000 mg) was dissolved in dimethylformamide and the volume adjusted to 100 mL to give a 1000 mg/100 mL solvent stock solution. Aliquots (1.3, 2.6, 5.3, 11 and
21 mL) of the 1000 mg/100 mL solvent stock solution were then each separately added to a final volume of 100 mL of dimethylformamide to give the further solvent stock solutions of 13, 26, 53, 110 and 210 mg/100 mL respectively.

Aliquots (200 µL) of these solvent stock solutions were then each separately dispersed in a final volume of 2 litres of Elendt M7 media with the aid of magnetic stirring for approximately
5 minutes to give the 0.013, 0.026, 0.053, 0.11 and 0.21 mg/L test concentrations.

Each solvent stock solution was inverted several times to ensure adequate mixing and homogeneity.

The test media was renewed daily due to the instability of the test item.

- Controls: Control of test water only, and solvent control of test water with 100 µl/L dimethylformamide

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

- Concentration of vehicle in test medium: final test solution(s): 100 µl/L, solvent control: 100 µl/L

- Evidence of undissolved material (e.g. precipitate, surface film, etc): No

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna

- Strain/clone: 1st instar

- Source: in-house laboratory cultures

- Age of parental stock (mean and range, SD): < 24 hrs

- Feeding during test: yes

- Food type: algal suspension (Desmodesmus subspicatus) and Tetramin® flake food suspension

- Amount: algal suspension: 2 to 7 µL, Tetramin: 10 to 32 µL

- Frequency: Daily

ACCLIMATION
- Acclimation period: Not specified, but Daphnia were kept in similar conditions prior to test: Daphnia were maintained in 150 mL glass beakers containing Elendt M7 medium in a temperature controlled room at approximately 20 °C, with a 16 hours light and 8 hours darkness cycle with 20 minute dawn and dusk transition periods

- Acclimation conditions (same as test or not): Same as test

- 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

METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES: The adult Daphnia were transferred to fresh media by wide-bore pipette before the contents of each vessel were passed through a fine mesh. Young daphnids (live and dead) and any unhatched eggs were collected on the mesh and counted before being discarded.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Post exposure observation period:

At the end of the test, the length of each surviving parent animal was determined

Hardness:

Range 250 - 460 mg/L as CaCO3 (in the solvent control and the highest surviving test concentration)

Test temperature:

20 - 21 °C

pH:

Range 7.2 - 8.2 (fresh and old media)

Dissolved oxygen:

Range 1.0 - 9.7 mg O2/L (fresh and old media)

Salinity:

Freshwater

Nominal and measured concentrations:

Nominal: 0.013, 0.026, 0.053, 0.11, 0.21 mg/L
Measured: Time-weighted mean: 0.0074, 0.015, 0.030, 0.062, 0.12 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:

- Type (delete if not applicable): closed with glass stopper

- Material, size, headspace, fill volume: Filled to top

- Aeration: None during test

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

- Renewal rate of test solution (frequency/flow rate): Daily

- No. of organisms per vessel: 1

- No. of vessels per concentration (replicates): 10

- No. of vessels per control (replicates): 10

- No. of vessels per vehicle control (replicates): 10

- Biomass loading rate:

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

- Culture medium different from test medium: No

- Intervals of water quality measurement: Daily for pH, dissolved oxygen and temperature. Weekly for water hardness

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: 572 to 788 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Daily observations of Adults surviving, Number of adults with eggs in brood pouch, live young, dead young and unhatched eggs. Length of surviving adults at 21 days.

VEHICLE CONTROL PERFORMED: yes

RANGE-FINDING STUDY
- Test concentrations: 0.013, 0.026, 0.053, 0.11, 0.21 mg/L during acute Daphnia immobilisation test

- Results used to determine the conditions for the definitive study: Immobilisation of the Daphnia at each test concentration

Reference substance (positive control):

not specified

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

>= 0.12 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other: reproduction, growth and mobility

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

> 0.12 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

immobilisation

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

> 0.12 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

immobilisation

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

> 0.12 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

reproduction

Details on results:

- Mortality of parent animals: 10 - 20 %

- No. of offspring produced per day per female: Control: Range 0 - 229
Solvent control: Range 0 -121
0.0074 mg/L test group: Range 0 - 176
0.015 mg/L test group: Range 0 - 215
0.030 mg/L test group: Range 0 - 193
0.062 mg/L test group: Range 0 - 215
0.12 mg/L test group: Range 0 - 149

- Body length and weight of parent animals: Mean lengths (mm) of surviving Daphnids at day 21: Control: 4.37,
Solvent control: 4.2, 0.0074 mg/L test group: 3.94, 0.015 mg/L test group: 3.95, 0.030 mg/L test group: 4.08, 0.062 mg/L test group: 4.27,
0.12 mg/L test group: 4.12

- Type and number of morphological abnormalities: Not stated

- Type and number of behavioural abnormalities: Not stated

- Number of males and females (parental) Not stated

- Time to first brood release or time to hatch: Not stated

- Brood size: Not stated

- Time to sexual maturity: Not stated

- Other biological observations: Assessment of general condition and size of the parental Daphnia as compared with the controls

- Effect concentrations exceeding solubility of substance in test medium: No

Reported statistics and error estimates:

For the estimation of the LOEC and NOEC values the numbers of live young produced per adult over the duration of the test for the control, solvent control and each test groups were compared using one way analysis of variance incorporating Bartlett's test for homogeneity of variance (Sokal and Rohlf 1981) and the Williams test for differences between treatment means when several dose levels are compared with a zero dose control (Williams 1971). Results from the control, solvent control and each test group Daphnia length data, determined for the surviving daphnids on termination of the test, were compared using one way analysis of variance incorporating Bartlett’s test for homogeneity of variance (Sokal and Rohlf 1981) and Dunnett’s multiple comparison procedure for comparing several treatments with a control (Dunnett 1955). All statistical analyses were performed using the SAS computer software package (SAS 1999 - 2001).

There were no significant differences (P>=0.05) between the solvent control and the time-weighted mean measured test concentration of 0.12 mg/L test group in terms of numbers of live young produced per adult by Day 21. There were no statistically significant differences
(P>=0.05) between the control, solvent control and each test group in terms of length of the daphnids after 21 days exposure to the test item. It was not possible to calculate the EC50 value of the test since less than 50% mortality was observed at the highest test concentration of 0.12 mg/L based on time-weighted mean measured test concentrations.

Table 1. Nominal to Time-weighted Mean Measured Concentrations

Nominal Concentrations (mg/L)	Time-weighted Mean Measured Concentrations (mg/L)
0.013	0.0074
0.026	0.015
0.053	0.030
0.11	0.062
0.21	0.12

Table 2. Summary of Findings Following the Exposure Of Daphnia magna for 21 days

Concentration (mg/L)	% Survival of P1	Number of Live Young		Number of Dead Young		Number of Unhatched Eggs
		Total	Per Female (cumulative)	Total	Per Female (cumulative)	Total	Per Female (cumulative)
Control	90	1075	119	0	0	0	0
Solvent Control	80	866	108	0	0	0	0
0.0074	80	795	99	0	0	0	0
0.015	80	816	102	0	0	0	0
0.030	80	748	94	0	0	0	0
0.062	90	906	101	0	0	0	0
0.12	80	658	82	0	0	0	0

Validity criteria fulfilled:

yes

Remarks:

mortality of parent organisms and number of living offspring per parent were within the valid ranges.

Conclusions:

21-d NOEC of >=0.12 mg/L have been determined for the effects of the test substance on reproduction, growth and mobility of Daphnia magna based on time-weighted mean measured concentrations. Additionally, 21-d EC50 (immobilisation) value of >0.12 mg/L, and EC50 (reproduction) value of >0.12 mg/L were determined in the test which was conducted in accordance with the study guideline and with GLP. The result is considered to be valid.

Description of key information

Long-term toxicity to invertebrates: 21-d  NOEC ≥0.12 mg/l (TWA measured) (highest concentration tested) (OECD guideline 211).

Additional information

A 21 day NOEC of ≥0.12 mg/l (time-weighted mean measured concentration) (highest concentration tested) has been determined for the effects of the registration substance on reproduction and mobility of Daphnia magna (Harlan laboratories, 2013). In view of the 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.