Trichloro(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silane

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1997-05-27 to 1997-05-31

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0 (Control), 6.7, 13.4, 33.4 and 66.8 mg/L and test stock solution.

- Sampling method: A series of concentrations of the test substance in distilled, deionised water were prepared to assess their stability. Their carbon content was measured initially and then again after 24, 48 and 72 hours. The concentration of the freshly prepared stock solution (in tap water) used to prepare the test media was also determined.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: A 1000 mg/L stock solution was prepared by adding the test substance to tap water and then stirring for 18 hours followed by filtration.

- Controls: Tap water

Test organisms (species):

Cyprinus carpio

Details on test organisms:

TEST ORGANISM

- Common name: Common carp

- Source: Bio International B.V., Someren, Netherlands

- Length at study initiation (length definition, mean, range and SD): 2-3 cm

- Feeding during test: none

ACCLIMATION

- Acclimation period: 14 days

- Acclimation conditions: same as test

- Type and amount of food: TROUVIT at 1% of body weight per day

- Feeding frequency: daily

- Health during acclimation: <5% mortality in seven days prior to test

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Hardness:

12 ºdH

Test temperature:

20-21.9ºC

pH:

8.0-8.5

Dissolved oxygen:

89-98% ASV

Salinity:

not applicable

Nominal and measured concentrations:

Nominal initial loading rate of the test substance: 0 (Control) and 1000 mg/L.

Mean measured Dissolved Organic Carbon (DOC) concentration in fresh test media: 0 (Control) and 3.1 mg/L.

Details on test conditions:

TEST SYSTEM

- Test vessel: Aquaria

- Type: open

- Size, fill volume: 20 L with 10 L of test medium

- Aeration: yes

- Renewal rate of test solution: daily

- No. of organisms per vessel: 10

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

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

- Biomass loading rate: 0.69 g/L

TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: tap water from Gelsenwasser AG.

- Culture medium different from test medium: yes

- Intervals of water quality measurement: daily

OTHER TEST CONDITIONS

- Adjustment of pH: no

- Photoperiod: 16 h light, 8 h dark

EFFECT PARAMETERS MEASURED: mortality after 24, 48, 72 and 96 hours

TEST CONCENTRATIONS

- Justification for using less concentrations than requested by guideline: limit test

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 3.1 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: hydrolysis products

Basis for effect:

mortality (fish)

Remarks on result:

other: based on measured DOC concentration

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 3.1 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: hydrolysis products

Basis for effect:

mortality (fish)

Remarks on result:

other: based on measured DOC concentration

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

but exposure is to hydrolysis products

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 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: 0

- Other adverse effects control: none

Reported statistics and error estimates:

No effects were observed in the test and therefore statistical analysis was not required.

Sublethal observations / clinical signs:

Table 1. Results of analysis of test media and stability test media

Nominal test substance loading (mg/L)	Measured concentration at start (mg/L)	Measured concentration after 24 h (mg/L)	Measured concentration after 48 h (mg/L)	Measured concentration after 72 h (mg/L)	Mean measured concentration (mg/L)
66.8	66.8	54.8	56.3	53.7	57.9
33.4	31.2	28.0	27.4	26.8	28.4
13.4	13.3	11.3	13.1	12.2	12.5
6.7	6.8	5.1	5.2	7.0	6.0
Test medium  (Test medium stock solution. Initial nominal loading rate of 1000 mg/L)	2.1	3.8	5.5	1.0	3.1

No toxic effects were observed in the Control or the only test concentration.

Validity criteria fulfilled:

yes

Conclusions:

A 96-hour LC50 value of >3.1 mg/L and a NOECof ≥3.1 mg/L have been determined for the effects of the test substance on mortality of Cyprinus carpio based on mean measured initial Dissolved Organic Carbon (DOC) concentration. The test medium was prepared at an initial loading rate of 1000 mg/L of the substance and was subsequently filtered before introducing the test organisms. The test substance hydrolyses in water and it is likely that the test organisms were primarily exposed to the hydrolysis products of the substance.

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Please see the ecotoxicological discussion and aquatic toxicity endpoint summary for justification of read-across.

Reason / purpose for cross-reference:

read-across source

Test organisms (species):

Cyprinus carpio

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 3.1 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: hydrolysis products

Basis for effect:

mortality (fish)

Remarks on result:

other: based on measured DOC concentration

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 3.1 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: hydrolysis products

Basis for effect:

mortality (fish)

Remarks on result:

other: based on measured DOC concentration

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

but exposure is to hydrolysis products

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

but exposure is to hydrolysis products

Basis for effect:

mortality (fish)

Validity criteria fulfilled:

yes

Conclusions:

A 96-hour LC50 value of >3.1 mg/L and a NOECof ≥3.1 mg/L have been determined for the effects of the test substance on mortality of Cyprinus carpio based on mean measured initial Dissolved Organic Carbon (DOC) concentration. The test medium was prepared at an initial loading rate of 1000 mg/L of the substance and was subsequently filtered before introducing the test organisms. The test substance hydrolyses in water and it is likely that the test organisms were primarily exposed to the hydrolysis products of the substance.

Description of key information

Short-term toxicity to fish: 96-hour LC₅₀ >3.1 mg/l (measured) (highest concentration tested) (OECD Guideline 203 (Fish, Acute Toxicity Test)), read-across from an analogous/structurally related substance, [2-(perfluorohexyl)ethyl]triethoxysilane (CAS 51851-37-7, EC 257-473-3). The LC₅₀ is equivalent to >2.6 mg/l when expressed in terms of the silanol hydrolysis product.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

LC50

Effect concentration:

> 2.6 mg/L

Additional information

There are no reliable short-term fish toxicity data available for [2-(perfluorohexyl)ethyl]trichlorosilane (CAS 78560-45-9, EC 278-947-6), therefore good quality data for an appropriate structural analogue, [2-(perfluorohexyl)ethyl]triethoxysilane (CAS 51851-37-7), have been read across. Both substances have the same silanol hydrolysis product, [2-(perfluorohexyl)ethyl]silanetriol. The other hydrolysis products are hydrochloric acid and ethanol, respectively.

A 96-hour LC₅₀ value of >3.1 mg/l and a NOEC of ≥3.1 mg/l (measured) (highest concentration tested) have been determined for the effects of [2-(perfluorohexyl)ethyl]triethoxysilane (CAS 51851-37-7) on mortality of Cyprinus carpio based on mean measured initial Dissolved Organic Carbon (DOC) concentration. The test medium was prepared at an initial loading rate of 1000 mg/l of the substance and was subsequently filtered before introducing the test organisms.

In view of the test media preparation method/exposure regime it is possible that the long preparation time and high pH of the test solutions could influence the exposure of the organisms to [2-(perfluorohexyl)ethyl]triethoxysilane and its silanol hydrolysis product, [2-(perfluorohexyl)ethyl]silanetriol. However, due to the extremely low solubility of the test substance potentially limiting hydrolysis rate, it is unclear how much of the parent substance or silanol hydrolysis product was present in the test solution, but best use has been made of the available data.

The results may be expressed in terms of concentration of the hydrolysis product, [2-(perfluorohexyl)ethyl]silanetriol, by applying a molecular weight correction: (MW of silanol = 426.21 / MW of parent = 510.37) * >3.1 = >2.6 mg/l.

Refer to the discussion in IUCLID Section 6 for further discussion of the approach to chemical safety assessment for this registration substance, and justification for read-across used.