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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:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
1994-11-30 to 1994-12-02
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study was conducted according to an appropriate OECD test guideline, and in compliance with GLP, and was considered to be reliability 1 (reliable without restrictions). Read across to the registered substance is considered scientifically justified; the read across is considered to be reliability 2.
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
GLP compliance:
yes (incl. certificate)
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 398 mg/L which was equivalent to 907 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:
7.8
Dissolved oxygen:
8.2 - 8.4 mg/L
Salinity:
not applicable
Nominal and measured concentrations:
Nominal: 0(Control), 54, 91, 163, 272, 481 and 816 mg/L

Measured concentration in stock solution used to prepare test media: 907 mg/L

Measured concentration in treatments at the start of the test: 58, 92, 190, 270, 488 and 814 mg/L

Measured concentration in treatments at the end of the test: 57, 90, 166, 266, 475 and 785 mg/L

Concentrations used as the basis for assessing effects: Control, 54, 91, 163, 272, 481 and 816 mg/L
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.:
> 816 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
but exposure is to hydrolysis products
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
>= 816 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: 0

- 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 were no toxic effects observed in the highest test concentrations and therefore statistical analysis of the results was not carried out.

Table 1. Test results

 Nominal test concentration (mg/L)  Mean percentage immobilisation after 24 hours  Mean percentage immobilisation after 48 hours
 0 (Control)  0  0
 54  0  0
 91  0  0
 163  5  5
 272  5  5
 481  0  0
 816  0  0
Validity criteria fulfilled:
yes
Conclusions:
A 48-h EC50 value of >816 mg/L and NOEC of ≥816 mg/L have been determined for the effects of the test substance on mobility of Daphnia magna based on nominal concentrations of the substance. It is likely that the test organisms were exposed to the hydrolysis products of the substance.

Description of key information

Short-term toxicity to invertebrates: 48 hour EC50 >816 mg/l (mean measured DOC) (highest concentration tested) (EU Method C.2 (Acute Toxicity for Daphnia)), read-across from an analogous/structurally related substance, trimethoxy(propyl)silane (CAS 1067-25-0). The observations in this study are attributed to the exposure of test organisms to the hydrolysis products in the test system.

Key value for chemical safety assessment

Additional information

There are no reliable short-term invertebrate toxicity data available for trichloro(propyl)silane (CAS 141-57-1), therefore good quality data for an appropriate structural analogue, trimethoxy(propyl)silane (CAS 1067-25-0), have been read across. Both substances share the same silanol hydrolysis product, propylsilanetriol. The other hydrolysis products are hydrochloric acid and methanol, respectively. In the test with trimethoxy(propyl)silane (CAS 1067-25-0), the observations are attributed to the exposure of test organisms to propylsilanetriol in the test system. There is no basis to expect that methanol significantly influenced the results of the test. The toxicity of methanol is discussed further in the ecotoxicological information overview endpoint summary (additional information).

 

A 48-hour EC50 value of >816 mg/l (mean measured DOC) (highest concentration tested) have been determined for the effects of trimethoxy(propyl)silane (CAS 1067-25-0) on mobility of Daphnia magna. In view of the test media preparation method and exposure regime it is likely that the test organisms were exposed predominantly to the hydrolysis products of the tested substance. The test concentrations are reported in terms of DOC and are therefore not further adjusted in terms of concentration of parent corrected to concentration of silanol.

 

Above a concentration of approximately 1000 mg/l, dimeric / oligomeric, cyclic or cross-linked condensation products could potentially form over time in the aqueous test media. No evidence of undissolved material (parent substance or precipitated products) is indicated in the study report for this test. 

 

Refer to the discussion in the Section 6 endpoint summary (Section 7.0 of CSR) for further discussion of the approach to chemical safety assessment for this registration substance, and justification for read-across used.