Triethoxysilane

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:

2002-08-06 to 2002-09-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: 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

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Nominal concentrations: 0 (Control), 10 and 100 mg/L

- Sampling method: An aliquot of test medium from all test concentrations at the start of the test before filling the test vessels. A combined aliquot was collected from the test media from all four exposure vessels of all test concentrations at the end of the test (48 hours).

- Sample storage conditions before analysis: All samples were stored at -20ºC prior to analysis.

Vehicle:

no

Details on test solutions:

- Method: A 100 mg/L stock solution was prepared by adding 100 mg of the substance to 1 litre of dilution water and stirring intensely for 30 minutes. A lower (10 mg/L) concentration was prepared by dilution of the stock solution.

- Controls: Dilution water

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
Strain: Daphnia magna strauss
- Source: Laboratory culture derived originally from IRChA, France

- Age at study initiation: 6-24 hours

- Feeding during test: none

ACCLIMATION

- Acclimation conditions: same as test
Acclimation period: 1 week
- Type and amount of food: Unicellular algae (Scenedesmus subspicatus) and small amount of aerated sewage.

- Feeding frequency: No data

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

250 mg/L as CaCO3

Test temperature:

20 +/-1ºC

pH:

7.95-8.12

Dissolved oxygen:

≥75% ASV

Nominal and measured concentrations:

Nominal concentrations: 0(Control), 10 and 100 mg/L

Measured DOC concentrations were within +/-20% of the theoretical values at the start and end of the test. The test results are therefore presented and interpreted with reference to the nominal concentrations as the sunstance is sensitive to hydrolysis

Details on test conditions:

TEST SYSTEM

- Test vessel:

- Type: no data

- Material, size: glass, 50 mL

- Aeration: none

- No. of organisms per vessel: 5

- No. of vessels per concentration (replicates): 4

- No. of vessels per control (replicates): 4

- Biomass loading rate: 1 daphnid/10 mL

TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: Reconstituted fresh water prepared by adding salts to demineralised water, according to guidline

- Alkalinity: 0.8 mmol/L

- Ca/mg ratio: 4:1

- Culture medium different from test medium: No

- Intervals of water quality measurement: Start and end of test

OTHER TEST CONDITIONS

- Adjustment of pH: No

- Photoperiod: 16 hours light, 8 hours dark

- Light intensity:500 lux (+/-20%)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): Mobility after 24 and 48 hours

TEST CONCENTRATIONS

- Spacing factor for test concentrations: 10

- Range finding study: no

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

but exposure is to hydrolysis products

Basis for effect:

mobility

Details on results:

- Immobilisation of controls: 5%

Reported statistics and error estimates:

An EC50 could not be determined from the test results because there was insufficient immobilisation (10%) in the highest treatment. The NOEC was determined directly from the raw data.

Table 1. Test results

Nominal test substance concentration (mg/L)	Mean percentage immobilisation after 24 hours	Mean percentage immobilisation after 48 hours
0 (Control)	0	5
10	5	5
100	5	10

Table 2. Results of analysis of test media

Nominal test substance concentration (mg/L)	Theoretical DOC concentration (mg/L)	Actual DOC concentration at start of test (mg/L)	Actual DOC concentration at end of test (mg/L)
10	4.39	4.5	4.2
100	43.9	45.0	44.5

Validity criteria fulfilled:

yes

Conclusions:

A 48-h EC50 value of >100 mg/L and a NOEC of <10 mg/L have been determined for the effects of the test substance on mobility of Daphnia magna based on nominal concentrations of the substance. The test substance hydrolyses in water. It is therefore likely that the test organisms were primarily exposed to the hydrolysis products of the substance.

Description of key information

(96-h) LC50: > 100 mg/L mortality Daphnia magna. Reliability 2.

Additional information

A 48-h EC50 value of >100 mg/L (OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test, LPT 2003) has been determined for the effects of the test substance on the mobility of Daphnia magna based on nominal concentrations of the substance. It has to be taken into consideration for interpretation that the test substance hydrolyses rapidly in water and that the test organisms were primarily exposed to the hydrolysis products. Therefore, the environmental hazard assessment, including sediment and soil compartments due to water and moisture being present, is based on the properties of the hydrolysis product, ethanol.