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

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1997-04-22 to 1997-04-24

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:

not specified

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 articial fresh 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 artificial fresh water and then stirring for 18 hours followed by filtration.

- Controls: Artificial fresh water

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM

- Strain: Clone 5

- Source: Own laboratory culture

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

- Method of breeding: Parthenogenic reproduction

- Feeding during test: none

ACCLIMATION

- Acclimation conditions: same as test

- Type and amount of food: Scenedesmus subspicatus is added to the cultures in amounts such that it is all consumed prior to feeding again the next day.

- Feeding frequency: daily

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

250 mg/L as CaCO3

Test temperature:

20+/-1ºC

pH:

7.9-8.0

Dissolved oxygen:

8.2-8.6 mg/L

Salinity:

not applicable

Nominal and measured concentrations:

Nominal loading rate: 0 (Control) and 1000 mg/L

Dissolved organic carbon (DOC) concentration of stock solution: 9 mg/L

Dissolved organic carbon (DOC) concentration of test media at start of test: 10 mg/L.

Results of the analysis of media prepared for assessing the stability of the test solutions showed that for nominal concentrations in the range 6.7 to 66.8 mg/L the concentration after 72 hours was at least 80% of that in the freshly prepared media.

The test results are interpreted with respect to the measured DOC concentration of the stock solution (9 mg/L) and the initial loading rate of the test substance used in the preparation of the stock solution (1000 mg/L).

Details on test conditions:

TEST SYSTEM

- Test vessel: Rimmed test tubes

- Type: open

- Material, size, headspace, fill volume: glass, 10 mL with 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

- Biomass loading rate: 2 mL/test organism


TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: Artificial fresh water

- Ca/mg ratio: 4:1

- Culture medium different from test medium: yes (Elendt M4 medium used for culture)

- Intervals of water quality measurement: Start and end of test


OTHER TEST CONDITIONS

- Adjustment of pH: no

- Photoperiod: Continuous darkness


EFFECT PARAMETERS MEASURED: Mobility after 24 and 48 hours


TEST CONCENTRATIONS

- Spacing factor for test concentrations: not applicable

- Justification for using less concentrations than requested by guideline: not reported

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 9 mg/L

Nominal / measured:

nominal

Conc. based on:

other: hydrolysis products

Basis for effect:

mobility

Remarks on result:

other: based on measured DOC concentration

Duration:

48 h

Dose descriptor:

NOELR

Effect conc.:

>= 9 mg/L

Nominal / measured:

nominal

Conc. based on:

other: hydrolysis products

Basis for effect:

mobility

Remarks on result:

other: based on measured DOC concentration

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

> 1 000 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:

NOELR

Effect conc.:

>= 1 000 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

Results with reference substance (positive control):

- Results with reference substance valid? yes

- 24-h EC50: in the range 1-2 mg/L, which is within the normal range for the laboratory culture.

Reported statistics and error estimates:

Not applicable - no effects observed at the only test concentration

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

Nominal test substance concentration (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
9.0  (Test medium stock solution. Initial nominal loading rate of 1000 mg/L)	10	-	-	-	-

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

Validity criteria fulfilled:

yes

Conclusions:

A 48-hour EC50 value of >9.0 mg/L and a NOECof ≥9.0 mg/L have been determined for the effects of the test substance on mobility of Daphnia magna 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 aquatic invertebrates: 48-hour EC₅₀ >9.0 mg/l (measured) (highest concentration tested) (EU Method C.2 (Acute Toxicity for Daphnia)).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

> 9 mg/L

Additional information

A 48-hour EC₅₀ value of >9.0 mg/l (measured) (highest concentration tested) have been determined for the effects of [2-(perfluorohexyl)ethyl]triethoxysilane (CAS 51851-37-7, EC 257-473-3) on mobility of Daphnia magna 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.

As the extremely low water solubility of the test substance will limit hydrolysis, it is likely that the test organisms were exposed to parent substance.

Long-term aquatic invertebrate testing of the parent substance has not been considered feasible due to the very low water solubility of the substance (6.4E-06 mg/l) and very high log K_ow(7.2). These values indicate that maintaining stable aqueous test solutions will be extremely difficult. Furthermore, once dissolved, the substance will have the tendency to adsorb onto the glassware under experimental conditions and onto dissolved organic matter in the natural environment.

Refer to IUCLID Section 6.1 and Section 7.1 of the CSR for discussion of the surface active properties of the parent substance, silanol hydrolysis product and condensation products and further discussion of the hydrolysis rates of the parent substance.