Reaction mass of 1,3-dimethyl-1,1,3,3-tetraphenyldisiloxane and 1,3,3,5-tetramethyl-1,1,5,5-tetraphenyltrisiloxane and 1,3,3,5,5,7-hexamethyl-1,1,7,7-tetraphenyltetrasiloxane

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:

August - October 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)

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

The water-accommodated fraction was prepared for the test. This was done by weighing the nominal load of 1000 ± 1 mg/L, resp. 935 ± 1 µL/L test item (based on a density of 1.07 g/mL), adding the corresponding amount of dilution water and stirring at 130 rpm for 7 days. After a settling phase of 24 ± 1 hours the lower phase of the resulting solution was taken and used for the test.
Dilution water used for the test as negative control was also stirred at 130 rpm for 7 days and let to stand for 24 ± 1 hours

Test organisms (species):

Daphnia magna

Details on test organisms:

Species Daphnia magna
Authority STRAUS
Strain Berlin
Sex female
Age between 0 and 24 hours
Origin Umweltbundesamt Berlin

Animal Husbandry
Vessels preserving glasses, nominal volume 2 L
Medium M4-Medium (recipe of ELENDT)
Food green algae (Desmodesmus subspicatus)
Medium renewal twice a week
Photo period 16/8 hours, using neon tubes
Temperature 20 +/- 2 °C

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

Resulting hardness in mmol/L: 2.502
Resulting hardness in mg CaCO3/L: 250

Test temperature:

19.5 – 21.1 °C

pH:

pH 0 h pH 48 h
Blank control 7.9 7.9
1000 mg/L (nominal) 7.9 7.9

Dissolved oxygen:

O2-Concentration in mg/L - 0 h O2-Concentration in mg/L - 48 h
Blank control 8.4 8.2
1000 mg/L (nominal) 8.5 8.3

Nominal and measured concentrations:

Nominal concentration in mg/L Calculated test item concentration based on Si measurement
at t = 0 h in µg/L
Blank Control --
1000 500.6

Details on test conditions:

Treatments: 1000 mg/L (nominal) The concentrations to be tested are based on the result of a non-GLP pre-test.
Temperature: 19.5 – 21.1 °C
Duration: 48 hours
Observation times: 24 and 48 hours
Medium renewal: none
Test vessels: glass beakers, nominal volume 50 mL, tall shape
Replicates (Treatment): 4 vessels, each containing 20 ± 5 mL test solution and 5 daphnia
Replicates (Blank control): 4 vessels, each containing 20 ± 5 mL dilution water and 5 daphnia

Reference substance (positive control):

yes

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 500.6 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

> 500.6 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

>= 500.6 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

NOELR

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

LOELR

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Results with reference substance (positive control):

The 24h-EC50i value was determined as 1.9 mg/L.

Validity criteria fulfilled:

yes

Executive summary:

The short term toxicity of the test item against Daphnia magna Straus was determined according to OECD 202 resp. EU C.2 One valid experiment was performed.

The study was performed using one concentration of 1000 mg/L (nominal). For the test concentration and the blank control, 20 Daphnia were exposed to the test item for 48 hours under static conditions. After 24 and 48 hours, the immobilised Daphnia were counted.

The tested concentration showed toxicity of 10 % immobilisation after 48 hours. None of the animals was immobilised in the blank control.

Potassium dichromate was used as positive control in a current reference study to assure that the test conditions are reliable.

At the start and at the end of the study, the content of the test item in the test solution was determined based on Si measurement as component of the test item (17.1 %). The Si content was determined via ICP-OES measurement. The Si content was measurable in the test solution and in the control, but in very low concentration. The Si content of the control solutions was subtracted from the Si content in the test solutions. During the study, the Si content in the solutions was increased. This was caused by Si dissolving out of the glass vessels. The Si content in the test solution was increased more than in the control solution. Therefore, the determination of the result was based on the measured concentration at the beginning. Nevertheless, it was shown that test item was present throughout the study.

Description of key information

The short term toxicity of the test item against Daphnia magna Straus was determined according to OECD 202 resp. EU C.2.

The study was performed using one concentration of 1000 mg/L (nominal).

The key values based on nominal concentrations are:

NOELR ≥ 1000 mg/L

LOELR > 1000 mg/L

EL50 > 1000 mg/L

Additional information

At the start and at the end of the study, the content of the test item in the test solution was determined based on Si measurement as component of the test item (17.1 %). The Si content was determined via ICP-OES measurement. The Si content was measurable in the test solution and in the control, but in very low concentration. The Si content of the control solutions was subtracted from the Si content in the test solutions. During the study, the Si content in the solutions was increased. This was caused by Si dissolving out of the glass vessels. The Si content in the test solution was increased more than in the control solution. Therefore, the determination of the result was based on the measured concentration at the beginning.

Nevertheless, it was shown that test item was present throughout the study.