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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1995-01-17 to 1995-01-19
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
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:
Test substance concentration determined in the stock solution used to prepare the test media.

Test substance concentration was determined in all treatments at the start and end of the test.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: A 1000 mg/l stock solution was prepared by mixing for 18 hours followed by filtration. The other treatments were prepared by dilution of the stock solution. The measured DOC concentration in the stock solution was 427 mg/l which was equivalent to 986 mg/l of the test substance.

- Controls: Dilution water
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM

- Common name: Daphnia magna

- Strain: Clone 5

- Source: Stock culture

- Age at study initiation (mean and range, SD): <24 h

- Method of breeding: Parthenogenetic reproduction

- Feeding during test: None

ACCLIMATION

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

- Type and amount of food: sufficient to be consumed each day leaving no residue

- Feeding frequency: daily
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
The sum of the Ca2+ and Mg2+ ions was 2.5 mmol
Test temperature:
20 +/-1ºC
pH:
8.0 - 8.3
Dissolved oxygen:
8.0 - 8.4 mg/l
Salinity:
not applicable
Nominal and measured concentrations:
Nominal: 0(Control), 20, 35, 59, 108 and 197 mg/l

Measured concentration in stock solution used to prepare test media: 986 mg/l

Measured concentration in treatments at the start of the test: 0, 26, 36, 59, 106 and 194 mg/l

Measured concentration in treatments at the end of the test: 0, 19, 33, 58, 105 and 156 mg/l

The test results are interpreted with reference to nominal concentrations.
Details on test conditions:
TEST SYSTEM

- Test vessel:

- Type: open

- Material, size, headspace, fill volume: glass cylinder containing 10 ml of test medium

- Aeration: none

- No. of organisms per vessel: 5

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

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

TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: Elendt M4 medium

- Intervals of water quality measurement: end of test

OTHER TEST CONDITIONS

- Photoperiod: Dark

EFFECT PARAMETERS MEASURED: Immobilization after 24 and 48 h exposure

TEST CONCENTRATIONS

- Spacing factor for test concentrations: 1.7
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
81 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
but exposure is to hydrolysis products
Basis for effect:
mobility
Remarks on result:
other: 59-108 mg/L
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
35 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
but exposure is to hydrolysis products
Basis for effect:
mobility
Details on results:
- Mortality of control: 10%

- Other adverse effects control: none reported
Results with reference substance (positive control):
48-h EC50: >1.0, <2.0 mg/l
Reported statistics and error estimates:
The EC50 and its confidence interval were determined by Probit analysis. The NOEC value was obtained directly from the raw data.

Table 1. Test results

 Nominal test concentration (mg/l)  Mean percentage immobilisation after 24 hours  Mean percentage immobilisation after 48 hours
 0 (Control)  0  10
 20  0  0
 35  0  0
 59  10  15
 108  50  80
 197  90  90
Validity criteria fulfilled:
yes
Conclusions:
A 48 hour EC50 value of 81 mg/l and a NOEC of 35 mg/l have been determined for the effects of the test substance on mobility of Daphnia magna. The results are expressed relative to nominal concentrations of the test substance. However the substance is subject to rapid hydrolysis and under the test conditions it is therefore likely that exposure will have been to its hydrolysis products (methanol and trisilanols).

Description of key information

EC50 (48 h): 81 mg/l mobility Daphnia magna (Hüls 1995)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
81 mg/L

Additional information

A 48-hour EC50 value of 81 mg/l and NOEC of 35 mg/l have been determined for the effects of the test substance on mobility of Daphnia magna. The results are expressed relative to nominal concentrations of the test substance. However the substance is subject to rapid hydrolysis and under the test conditions it is therefore likely that exposure will have been to its hydrolysis products (methanol and N-(3-(trihydroxysilyl)propyl)ethylenediamine).

This result has been selected as the lowest EC50 value for effects on mobility from two reliable studies. The other EC50 value was 90 mg/l and the corresponding NOEC was <63 mg/l.

Another study to which it is not possible to assign a reliability score determined an EC50 value of 37 ppm and a NOEC of <10 ppm.

The study with lowest EC50 value has been selected as key study as a worst case scenario.