Hexadecyltrimethoxysilane

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2002-04-15 to 2002-07-25

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Guideline study with restrictions. The study was conducted according to an appropriate OECD test guideline, with acceptable restrictions. The restrictions were that the analytical results showed that measured DOC concentrations were <5% of nominal. The results have been reinterpreted with reference to the measured concentrations of dissolved organic carbon in the test media

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

yes

Remarks:

Test media were not prepared in accordance with OECD guidance for testing difficult substances

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Nominal treatments: 100 mg/L and 10 mg/L (10% concentration of 100 mg/L water-soluble fraction)
- Sampling method: A sample of test media were taken from all treatments at the start (before introducing the test organisms) and at the end of the test.
- Sample storage conditions before analysis: Not reported

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: A water-soluble fraction of the test substance was prepared by mixing 100 mg/l of the test substance with dilution water for 48 hours and then filtering (0.45 μm) to remove undissolved test substance. The water-soluble fraction was tested undiluted and at one-tenth of its original concentration.

- Controls: Dilution water

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM

- Strain: IRCHA

- Source: LPT Laboratory Culture

- Age at study initiation (mean and range, SD): 6-24 hours

ACCLIMATION

- Acclimation period: at least one week

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

- Type and amount of food: algae (Scenedesmus subspicatus) plus a small quantity of sewage (only during the holding period) from the aerated phase of treatment

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

250 mg/L as CaCO3

Test temperature:

20+/-1ºC

pH:

7.61-8.15

Dissolved oxygen:

≥80% ASV

Nominal and measured concentrations:

Nominal loading rates: 0(Control), 100 mg/L and 10 mg/L (10% concentration of 100 mg/L water-soluble fraction).

A loading rate of 100 mg/L is above the expected solubility of the substance in the test medium. Measured dissolved organic carbon concentrations were below 5% of the theoretical values at the start and end of the test.

Details on test conditions:

TEST SYSTEM

- Test vessel:

- Type (delete if not applicable): open

- Material, size: glass, 38 mm diameter, 60 mm tall, 50 mL volume

- Aeration: none

- No. of organisms per vessel: 5

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

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

TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: aerated reconstituted water

- Alkalinity: 0.8 mmol/L

- Ca/mg ratio: 4:1

- Culture medium different from test medium: no

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

OTHER TEST CONDITIONS

- Adjustment of pH: no

- Photoperiod: 16 h light/8 h dark

- Light intensity: 500 Lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): Mobility after 24 and 48 hours

TEST CONCENTRATIONS

- Spacing factor for test concentrations: 10

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOELR

Effect conc.:

< 10 other: percent concentration of the 100 mg/l water-soluble fraction

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Immobilization of control: 5%

- Effect concentrations exceeding solubility of substance in test medium: A loading rate of 100 mg/L is above the expected solubility of the substance in the test medium.

Reported statistics and error estimates:

There were insufficient toxic effects to determine an EL50 value. The EC50 and NOELR values were determined directly from the raw data.

Table 1. Test results

Nominal test substance loading rate (mg/L)	Mean percentage immobilisation after 24 hours	Mean percentage immobilisation after 48 hours
0 (Control)	0	5
10 (10% concentration of 100 mg/L water-soluble fraction)	0	10
100	0	15

Table 2. Results of analysis of test media

Nominal test substance loading rate (mg/L)	Theoretical DOC concentration (mg/L)	Actual DOC concentration at start of test (mg/L)	Actual DOC concentration at end of test (mg/L)
10 (10% concentration of 100 mg/L water-soluble fraction)	6.6	<0.5	0.5
100	65.8	<0.5	0.9

Validity criteria fulfilled:

yes

Conclusions:

A 48-h EL50 value of >100 mg/L has been determined for the effects of the test substance on mobility of Daphnia magna based on nominal loading rate of the test substance. The NOELR in the test corresponded to a <10% concentration of the 100 mg/L water soluble fraction.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1989-12-13 to 1989-12-15

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: 2 g of the test substance was added to 2 L of dilution water in a glass-stoppered conical flask and vigorouslt stirred at a temperature of 20+/1ºC for 24 hours. After standing for 24 hours a portion was then drawn off. A second portion was drawn off after standing for a further 24 hours. Both portions were then subsject to testing.

- Controls: Dilution water

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM

- Source: Laboratory culture

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

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

24 h

Hardness:

215 mg/l as CaCO3

Test temperature:

20+/-1ºC

pH:

7.8-8.0

Dissolved oxygen:

7.7-8.8 mg/L

Salinity:

not applicable

Nominal and measured concentrations:

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

A 1000 mg/L loading rate is well above the expected solubility of the substance in the test medium.

Details on test conditions:

TEST SYSTEM

- Test vessel: Beakers

- Type: open

- Material, size, fill volume: glass, 150 mL with 100 mL fill volume

- Aeration: none

- Renewal rate of test solution (frequency/flow rate): none

- No. of organisms per vessel: 5

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

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


TEST MEDIUM / WATER PARAMETERS

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

- Ca/mg ratio: 1.8/1

- Culture medium different from test medium: no


OTHER TEST CONDITIONS

- Adjustment of pH: no

- Photoperiod: 16 h light, 8 h dark


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Immobilization

Reference substance (positive control):

no

Duration:

24 h

Dose descriptor:

EL50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

NOELR

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: Test organisms exposed to the medium that had been settled for only 24 hours were trapped in a surface film of undissolved test substance but were not immobile. Those exposed to the medium that had stood for 48 hours were completely unaffected.

- Mortality of control: 0
- Other adverse effects control: none

Reported statistics and error estimates:

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

No toxic effects were observed in the test.

Validity criteria fulfilled:

yes

Conclusions:

A 24-h EL50 value of >1000 mg/L and NOELR of ≥1000 mg/L have been determined for the effects of the test substance on mobility of Daphnia magna based on nominal loading rate of the test substance.

Description of key information

EL50 (48) > 100 mg/L (nominal, Daphnia magna, OECD 202)

Additional information

Two studies are available testing the short term toxicity of hexadecyl(trimethoxy)silane (CAS No. 16415-12-6) to Daphnia magna. Both studies were performed according to the OECD guideline 202 and GLP standards.

 

In the key study Daphnia magna was exposed over 48 h to the nominal loading rates of 0 (control), 100 mg/L and 10 mg/l (10% concentration of 100 mg/l water-soluble fraction). The test solutions were analytically monitored via DOC analysis. Since the tested substance is poorly water soluble analytical results showed that measured DOC concentrations were <5% of nominal. An EL50 value of >100 mg/L (nominal loading rate) was determined in this study.

 

A supporting study is available (1990). Daphnia magna was exposed to a single concentration of 1000 mg/L. No effects on the mobility of Daphnia magna were determined over a study period of 24 h resulting into an EL50 (24 h) of > 1000 mg/L (nominal).