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Short-term toxicity to fish

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Endpoint:
short-term toxicity to fish
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1994-04-26 to 1994-04-30
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
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).
Qualifier:
according to
Guideline:
EU Method C.1 (Acute Toxicity for Fish)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
not specified
Details on sampling:
- Concentrations: 500 mg/l

- Sampling method: Samples of test media were taken from all treatments at the start and end of the first (0-24h) and third (48-72h) test periods.

- Sample storage conditions before analysis: refrigerated
Vehicle:
not specified
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: A stock solution was prepared by mixing the substance overnight with dilution water used in the test

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

- Common name: Zebrafish

- Source: Tropical Waters (Feltham, UK)

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

- Length at study initiation (length definition, mean, range and SD): 3.4 cm (3.1 - 3.7 cm)

- Weight at study initiation (mean and range, SD): 0.38 g (0.3 - 0.45 g)

- Feeding during test: None

ACCLIMATION

- Acclimation period: 12 days

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

- Type and amount of food: TetraMin® Tropical Flake

- Feeding frequency: dependent upon size and temperature

- Health during acclimation (any mortality observed): Cumulative mortality must no exceed 5% in the 7-day period prior to the test.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Hardness:
40.8 - 41.3 mg/l
Test temperature:
20 - 21ºC
pH:
7.0 - 7.5
Dissolved oxygen:
62 - 100% ASV
Nominal and measured concentrations:
Nominal: Control, 31.25, 62.5, 125, 250 and 500 mg/l.

Measured concentrations in fresh media (excluding Control) at start of test: 27.2, 58.5, 119, 249 and 499 mg/l.

Measured concentrations in old media (excluding Control) after 24 h exposure: 30.7, 63.4, 124, 248 and 497 mg/l.

Measured concentrations in fresh media (excluding Control) at 48 h: 32, 64.6, 124, 241 and 490 mg/l.

Measured concentrations in old media (excluding Control) after 24 h exposure: 28.1, 59.9, 117, 232 and 492 mg/l.

Mean measured concentrations: 29.4, 61.5, 121, 242 and 494 mg/l.

Mean measured concentrations as a % of nominal: 94.1, 98.4, 96.6, 96.9 and 98.9.
Details on test conditions:
TEST SYSTEM

- Test vessel: Culture vessels

- Type: sealed

- Material: Glass

- Aeration: none

- Renewal rate of test solution (frequency): daily

- No. of organisms per vessel: 10

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

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

- Biomass loading rate: 0.38 g/l

TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: Laboratory mains supply

- Chlorine: <0.1 mg/l (Total)

- Alkalinity: 14 mg/L CaCO3

- Conductivity: 128 µS/cm

- Culture medium different from test medium: no

- Intervals of water quality measurement:

OTHER TEST CONDITIONS

- Adjustment of pH: no

- Photoperiod: 16 h (light)/8 h (dark)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

TEST CONCENTRATIONS

- Spacing factor for test concentrations: 2.0
Reference substance (positive control):
no
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
> 500 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
but exposure is to hydrolysis products
Basis for effect:
mortality
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
>= 500 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
but exposure is to hydrolysis products
Basis for effect:
mortality
Details on results:
- Behavioural abnormalities: At the end of the testfish exposed to the 250 mg/l nominal test concentration were showing mild toxic effects and those exposed to 500 mg/l severe toxic effects.

- Mortality of control: 0
Reported statistics and error estimates:
There were no toxic effects at the highest test concentration and therefore statistical analysis of the results was not carried out.
Validity criteria fulfilled:
yes
Conclusions:
A 96-hour LC50 value of >500 mg/l and NOEC of =500 mg/l have been determined for the effects of the test substance on mortality of Brachydanio rerio based on nominal concentration of the substance. However it is likely that the test organisms were primarily exposed to the hydrolysis products of the substance.
Endpoint:
short-term toxicity to fish
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2007-06-29 to 2007-07-12
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
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).
Qualifier:
according to
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Sampling: Measurement of test concentrations in one replicate test chamber of each treatment group at test initiation and at test termination.
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: Test solutions were prepared by direct addition of test article to dilution water (100 and 200 mg/l treatment groups) or by addition of  stocks prepared in DMF (13, 25 and 50 mg/l treatment groups).
Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Details on test organisms:
TEST ORGANISM

- Test fish (age/length/weight, loading, pretreatment):  Age 50 Days/Mean Total Length 3.7 cm (Range 3.4 to 4.0 cm)/Wet Weight 0.37 g (Range 0.30 to 0.51 g), Flow-Through Loading 0.035 g/l/24 hours, Instantaneous Loading 0.25 g/l, Fish were acclimated to laboratory conditions for a minimum of 2 weeks prior to the test.

- Supplier: Thomas Fish Company
Test type:
flow-through
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Hardness:
Hardness 138 mg/l as CaCO3, Alkalinity 74 mg/l as CaCO3
Test temperature:
11.4 - 12.1ºC
pH:
7.3-7.7
Dissolved oxygen:
7.6-9.1 mg/l
Salinity:
Not applicable
Nominal and measured concentrations:
Nominal concentrations: Negative Control, Solvent Control, 13, 25, 50, 100 and 200 mg/l

Mean measured concentrations: 
The results are interpreted with reference to mean measured concentrations.
Details on test conditions:
- Exposure vessel type:  25-litre polyethylene aquaria containing 15-litre of test solution

- Number of replicates, fish per replicate:  Two replicates per treatment, 10 Fish per replicate

- Dilution water source:  Dechlorinated Municipal Water

- Dilution water chemistry:  Hardness 138 mg/l as CaCO3, Alkalinity 74 mg/l as CaCO3, Conductivity 362 µmhos/cm, pH 7.6, Total Residual Chlorine <10  g/l        

- Vehicle/solvent and concentrations:  The solvent control, 13, 25 and 50 mg/l treatment groups contained 0.1 ml/l DMF.  No solvent was delivered in the 100 and 200 mg/l treatment groups.

- Water chemistry in test:  DO, pH and temperature measured in each test chamber daily
Reference substance (positive control):
no
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
> 110 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
>= 110 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
> 200 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
>= 200 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Reported statistics and error estimates:
There was no significant mortality in any treatment; statistical analysis was therefore not required.

Table 1. Test results

 Nominal concentration (mg/l)  Mean measured 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) < LOQ (<0.290)  0  0  0  0
 0 (Vehicle control)  < LOQ (<0.290)  0  0  0  0
 13 4.5  0  0  0  0
 25 11  0  0  0  0
 50 25  0  0  0  0
 100 52  0  0  0  0
 200 110  0  0  0  5

       
24-Hour LC50:  >110 mg/l (not calculable)
48-Hour LC50:  >110 mg/l (not calculable)
72-Hour LC50:  >110 mg/l (not calculable)
96-Hour LC50:  >110 mg/l (not calculable)

Biological observations:  All surviving fish appeared normal and healthy.   
Lowest test substance concentration causing 100% mortality:  None
Mortality of controls:  None
Abnormal responses:  None
Any observations, such as precipitation that might cause a
difference between measured and nominal values:  All test
solutions were clear and colorless.

Validity criteria fulfilled:
yes
Conclusions:
A 96-hour LC50 value of >110 mg/l and NOEC of =110 mg/l have been determined for the effects of the substance on mortality of Oncorhynchus mykiss. Under the flow-through conditions used in the test the results reflect exposure to the parent substance.

Description of key information

Short-term toxicity to fish: 96 hour LC50 >500 mg/l (nominal) (EU Method C.1 (Acute toxicity for fish)), read-across from an analogous/structurally related substance, triethoxy(methyl)silane (CAS 2031-67-6). The observations in this study are attributed to the exposure of test organisms to the hydrolysis products in the test system. The LC50 is equivalent to >213.7 mg/l when expressed in terms of the silanol hydrolysis product.

Key value for chemical safety assessment

Additional information

There are no reliable short-term fish toxicity data available for methylsilanetriyl triacetate (CAS 4253-34-3), therefore good quality data from appropriate structural analogues triethoxy(methyl)silane (CAS 2031-67-6) and trimethoxy(methyl)silane (CAS 1185-55-3), have been read across. The substances share the same silanol hydrolysis product, methylsilanetriol. The other hydrolysis products are acetic acid, ethanol and methanol, respectively. In the tests with triethoxy(methyl)silane (CAS 2031-67-6) and trimethoxy(methyl)silane (CAS 1185-55-3), the observations are attributed to the exposure of test organisms to methylsilanetriol in the test system. There is no basis to expect that ethanol or methanol significantly influenced the results of the test. The toxicity of ethanol and methanol is discussed further in the ecotoxicological information overview endpoint summary (additional information).

 

A 96 hour LC50 value of >500 mg/l (nominal, highest concentration tested) has been determined for the effects of triethoxy(methyl)silane (CAS 2031-67-6) on mortality of Danio rerio. 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 results may be expressed in terms of concentration of the hydrolysis product, methylsilanetriol, by applying a molecular weight correction: (MW of silanol = 94.14 / MW of parent = 220.26) * >500 = >213.7 mg/l. This value is read across to methylsilanetriol without further correction.

A 96 hour LC50 value of >110 mg/l has been determined for the effects of the second analogous read-across substance, trimethoxy(methyl)silane (CAS 1185-55-3), on mortality of Oncorhynchus mykiss. The result was obtained under flow-through exposure conditions and it is therefore likely that the test organisms were exposed to a mixture of the test substance and its hydrolysis products.

The study with triethoxy(methyl)silane (CAS 2031-67-6) has been selected as key because the organisms were likely to be exposed predominantly to the silanol hydrolysis product of the substance.