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Ecotoxicological information

Short-term toxicity to fish

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Reference
Endpoint:
short-term toxicity to fish
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1995-07-31 to 1995-08-04
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method C.1 (Acute Toxicity for Fish)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 100, 180, 350, 550 and 1000 mg/l and the fresh stock solutions used to prepare the test media.

- Sampling method: Concentrations of test substance hydrolysis products determined in fresh media at all concentrations after preparation and again before renewal after 24 hours. The concentrations of the fresh stock solutions used to prepare the test media was also determined.

- Sample storage conditions before analysis: not reported
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: Test media prepared by dilution of a 1000 mg/l stock solution. Stock solutions were prepared by stirring for 18 h followed by filtration. TOC concentration of stock solution determined and used as the basis for determining the nominal test concentrations.

- Differential loading: Five nominal test concentrations 100, 180, 350, 550 and 1000 mg/l

- Controls: Dilution water
Test organisms (species):
Danio rerio (previous name: Brachydanio rerio)
Details on test organisms:
TEST ORGANISM

- Common name: Zebrafish

- Source: West aquarium, Bad Lauterberg, Germany

- Length at study initiation (length definition, mean, range and SD): 3.0 cm +/-0.5 cm

- Feeding during test: none

ACCLIMATION

- Acclimation period: at least 14 days

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

- Type and amount of food: TetraMin® at 1% of body weight

- Feeding frequency: Daily

- Health during acclimation (any mortality observed): The fish exhibit normal behaviour and are free from visible signs of disease at the start of the test.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Hardness:
≈ 12ºdH
Test temperature:
20 - 22ºC
pH:
8.0 - 8.4
Dissolved oxygen:
84 - 111%
Salinity:
not applicable
Nominal and measured concentrations:
Nominal concentrations: 100, 180, 350, 550 and 1000 mg/l.

Initial measured concentrations: 100, 157, 334, 502 and 1005 mg/l.

Concentrations in media prior to replacement after 24 hours: 109, 156, 327, 514 and 929 mg/l.

Geometric mean measured concentrations (0-24h): 104, 156, 330, 508 and 968 mg/l.

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

- Test vessel:

- Type (delete if not applicable): open aquarium

- Material, size, headspace, fill volume: 20 litres

- Aeration: Continuous

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

- No. of organisms per vessel: 10

- No. of vessels per concentration (replicates): 1

- No. of vessels per control (replicates): 1

- Biomass loading rate: 0.49 g/l


TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: Potable water from Gelsenwasser AG


OTHER TEST CONDITIONS

- Adjustment of pH: None

- Photoperiod: 16 h light/8 h dark


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Mortality after 24, 48, 72 and 96 h


TEST CONCENTRATIONS

- Spacing factor for test concentrations: 1.8
Reference substance (positive control):
no
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
350 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
but exposure is to hydrolysis products
Basis for effect:
mortality (fish)
Key result
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
439 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
but exposure is to hydrolysis products
Basis for effect:
mortality (fish)
Remarks on result:
other: Concentrations bounding LC50: 350 - 550 mg/l
Duration:
72 h
Dose descriptor:
LC50
Effect conc.:
451 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
but exposure is to hydrolysis products
Basis for effect:
mortality (fish)
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
486 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
but exposure is to hydrolysis products
Basis for effect:
mortality (fish)
Duration:
24 h
Dose descriptor:
LC50
Effect conc.:
742 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
but exposure is to hydrolysis products
Basis for effect:
mortality (fish)
Details on results:
- Mortality of control: Zero
Reported statistics and error estimates:
LC50 determined by graphical interpolation
Sublethal observations / clinical signs:

Table 1. Test results

 Nominal test substance concentration (mg/l)  Percentage mortality after 24 hours Percentage mortality after 48 hours  Percentage mortality after 72 hours  Percentage mortality after 96 hours 
 0 (Control)  0  0  0  0
 100  0  0  0
 180  0  0  0  0
 350  0  0  0  0
 550  0  70  90  100
 1000  100  100  100  100
Validity criteria fulfilled:
yes
Conclusions:
A 96-h LC50 value of 439 mg/l and NOEC of 350 mg/l have been deternined for the effects of the test substance on mortality of Brachydanio rerio based on nominal concentrations of the substance. The test substance is susceptible to hydrolysis and it is therefore likely that the test organisms were primarily exposed to the hydrolysis products of the substance. The LC50 is equivalent to 345 mg/l when expressed in terms of the silanol hydrolysis product, 3-mercaptopropylsilanetriol.

Description of key information

No data are available for 3-(triethoxysilyl)propanethiol. A 96-hour LC50 value of 439 mg/l has been determined for the effects of a read-across substance, 3-(trimethoxysilyl)propane-1-thiol (CAS 4420-74-0), on the mortality of Brachydanio rerio. The LC50 is equivalent to 345 mg/l when expressed in terms of the silanol hydrolysis product, 3-(trihydroxysilyl)propanethiol.

A stepwise testing strategy is planned to address the requirements of the ECHA decision letter (TPE-D-2114432420-65-01/F). Please refer to the attachment in IUCLID Section 13. This read-across is retained as an interim measure to calculate a PNEC and support the existing chemical safety assessment until new evidence becomes available.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Effect concentration:
439 mg/L

Additional information

There are no reliable short-term fish toxicity data available for 3-(triethoxysilyl)propanethiol (CAS 14814-09-6) therefore good quality data for an appropriate structural analogue, 3-(trimethoxysilyl)propane-1-thiol (CAS 4420-7-0) are read-across. Both substances hydrolyse to the same hydrolysis product, 3-(trihydroxysilyl)propanethiol. Both substances have hydrolysis half-lives which indicate that, under conditions relevant to ecotoxicity assessment, both will partially hydrolyse to 3-(trihydroxysilyl)propanethiol over the course of the test.

 

A reliable, 96-hour LC50 value of 439 mg/L has been determined for the effects of 3 -(trimethoxysilyl)propane-1-thiol (CAS 4420 -74 -0) on the mortality of Danio rerio based on nominal concentrations of the substance (Hüls, 1995). In view of hydrolysis half-life of the parent substance, it is likely that the test organisms were exposed predominantly to the hydrolysis products of the tested substance.

 

The results may be expressed in terms of the concentration of the hydrolysis product, by applying a molecular weight correction (MW of silanol = 154.26 / MW of parent = 196.34) * (EC50 of parent = 439 mg/L) = 345 mg/L.

 

The study was considered to be reliability 1 (reliable without acceptable restrictions).