Trichloro(hexadecyl)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:

1989-12-12 to 1989-12-16

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:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: 1.5 g of test substance was added to 1.5 L of dilution water and stirred vigorously for 24 hours on a magnetic stirrer at a temperature of 25+/1ºC. The aqueous phase was then decanted into the test vessel as the test medium.

- Evidence of undissolved material (e.g. precipitate, surface film, etc): It is likely that the solubility of the substance in the test medium was exceeded. An oil-like substance was observed on the surface of the test media.

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM

- Common name: Zebrafish

- Source: obtained from a commercial hatchery; M.B. Ruysbroek B.V., Maassluis, The Netherlands.

- Length at study initiation (length definition, mean, range and SD): 2.2+/-0.1 cm

- Weight at study initiation (mean and range, SD): 0.08+/-0.01 g

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Hardness:

215 mg/l as CaCO3

Test temperature:

25+/-1ºC

pH:

7.6-8.0

Dissolved oxygen:

6.1-8.5 mg/L

Salinity:

not applicable

Nominal and measured concentrations:

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

It is likely that the solubility of the substance in the test medium was exceeded. An oil-like substance was observed on the surface of the test media.

Details on test conditions:

TEST SYSTEM

- Test vessel: beaker

- Type (delete if not applicable): open

- Material, size, fill volume: glass, 2 L with 1.5 L fill volume

- Aeration: none

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

- No. of organisms per vessel: 10

- No. of vessels per concentration (replicates): 4

- No. of vessels per control (replicates): 4

- Biomass loading rate: 0.52 g/L

TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: Synthetic freshwater (DSWL) prepared by the additional of salts to groundwater from near Linschoten, The Netherlands.

- Culture medium different from test medium: no

- Intervals of water quality measurement: Daily

OTHER TEST CONDITIONS

- Adjustment of pH: no

- Photoperiod: 16 h light, 8 h dark

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

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LL50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

NOELR

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

- Behavioural abnormalities: 0

- Mortality of control: 0

- Other adverse effects control: 0

- Abnormal responses: 0

- Effect concentrations exceeding solubility of substance in test medium: It is likely that the solubility of the substance in the test medium was exceeded. An oil-like substance was observed on the surface of the test media.

Reported statistics and error estimates:

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

Sublethal observations / clinical signs:

No toxic effects were observed in the test.

Validity criteria fulfilled:

yes

Conclusions:

A 96-h LL50 value of >1000 mg/L and NOELR of ≥1000 mg/L have been determined for the effects of the test substance on mortality of Brachydanio rerio based on nominal loading rate of the test 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 refer to attached justification for grouping of substances in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across source

Duration:

96 h

Dose descriptor:

LL50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

NOELR

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Description of key information

96-hour LL₅₀ > 1000 mg/L (nominal, Brachydanio rerio, OECD 203, based on read across to CAS No. 16415-12-6)

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

LC50

Effect concentration:

> 1 000 mg/L

Additional information

Measured acute data on the toxicity towards fish was not available for trichloro(hexadecyl)silane (CAS No. 5894-60-0), therefore data was read-across from the structural analogue substance trimethoxy(hexadecyl)silane (CAS No. 16415-12-6) for the assessment of acute toxicity towards fish. Both substances hydrolyse in the aquatic environment, but with very different hydrolysis rates (DT50 = << 2 min at room temperature and pH 7 (target); DT50 > 14 d at pH 7 (source)). However, both form the same silanol hydrolysis product hexadecylsilanetriol. The second hydrolysis product of the target substance is hydrochloric acid, while the second hydrolysis product of the source compound is methanol. Hydrochloric acid and methanol are both well described substances in the public domain literature and both are not expected to contribute to the overall aquatic toxicity of target and source substances (OECD SIDS, 2002; OECD SIDS 2004). Therefore, hydrochloric acid and methanol can be disregarded in the environmental hazard assessment. Further information can be found in an attached read-across justification in Section 13 of IUCLID.

 

In the valid acute fish toxicity test according to OECD guideline 203 and under GLP conditions, Brachydanio rerio was exposed to trimethoxy(hexadecyl)silane. In the 96-h limit test, the LC50 value of > 1000 mg/L and NOEC of ≥ 1000 mg/l have been determined for the effects of the substance on mortality of Brachydanio rerio based on nominal concentration (TNO, 1990).

The result was obtained under semi-static test conditions. In view of slow hydrolysis rate and exposure regime it is likely that the test organisms were exposed predominantly to the parent of the tested substance.

 

References:

OECD, 2002. Hydrogen Chloride - SIDS Initial Assessment Report for SIAM 15, Boston, USA: UNEP Publications.

OECD SIDS, 2004. Methanol - SIDS Initial Assessment Report For SIAM 19, Berlin, Germany: UNEP Publications.