Diethoxy(dimethyl)silane

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:

disregarded due to major methodological deficiencies

Study period:

Not reported

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

A 48-h EC50 value of 2.1 mg/L has been determined for the effects of the test substance on mobility of Daphnia pulex based on nominal concentrations of the substance. The study did not include analysis of the test media, details on the test media preparation as well as raw data on immobilisation in the treatments and controls. Moreover, relevant information are missing in order to check if the validity criteria according to todays standard methods are met. Thus, the study is not considered to be reliable and was not considered for the assessment. In addition, reliable and fully documented studies with substances that hydrolyse to the same hydrolysis report results in a much higher range (>100 mg/L or >limit of solubility).

Qualifier:

according to guideline

Guideline:

other: ASTM E729-80 (1980), US EPA 660/3-75-009 (1975)

GLP compliance:

not specified

Analytical monitoring:

no

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: Test media were prepared in reconstituted freshwater using acetone as a solvent.

- Controls: Dilution water + acetone

- Chemical name of vehicle (organic solvent, emulsifier or dispersant): acetone (2 propanone)

- Concentration of vehicle in test medium (stock solution and final test solution): (75μl/150 mL)

Test organisms (species):

Daphnia pulex

Details on test organisms:

TEST ORGANISM

- Source: Laboratory stock cultures maintained in accordance with the test guidelines

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

- Feeding during test: none


ACCLIMATION

- Acclimation period: no data

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

- Type and amount of food: A mixture of four species of algae combined with a cerophyl infusion at a volume ratio of 1:1:1:1:1:4.

- Feeding frequency: not reported

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

160-180 mg/L as CaCO3

Test temperature:

20ºC

pH:

no data

Dissolved oxygen:

8-9 mg/l

Salinity:

not applicable

Nominal and measured concentrations:

Control (with acetone) and five nominal concentrations

Details on test conditions:

TEST SYSTEM

- Test vessel: Beaker

- Type: no data

- Fill volume: 150 mL

- Aeration: no data

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

- No. of organisms per vessel: 10

- No. of vessels per concentration (replicates): 2

- No. of vessels per vehicle control (replicates): 2

- Biomass loading rate: 1 daphnid/15 mL of test medium


TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: Reconstituted freshwater

- Culture medium different from test medium: no

- Intervals of water quality measurement: no data


OTHER TEST CONDITIONS

- Adjustment of pH: no data

- Photoperiod: no data

- Light intensity: no data


EFFECT PARAMETERS MEASURED (with observation intervals if applicable): mobility after 48 hours


TEST CONCENTRATIONS

- Spacing factor for test concentrations: 1.7

- Range finding study: no data

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

2.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

but exposure is to hydrolysis products

Basis for effect:

mobility

Details on results:

- Control immobilisation: no data

Reported statistics and error estimates:

ECx values were calculated by Probit Analysis after Finney (1971)

Validity criteria fulfilled:

yes

Conclusions:

A 48-h EC50 value of 2.1 mg/L has been determined for the effects of the test substance on mobility of Daphnia pulex based on nominal concentrations of the substance. The study did not include analysis of the test media, details on the test media preparation as well as raw data on immobilisation in the treatments and controls. Moreover, relevant information are missing in order to check if the validity criteria according to todays standard methods are met. Thus, the study is not considered to be reliable and was not considered for the assessment. In addition, reliable and fully documented studies with substances that hydrolyse to the same hydrolysis report results in a much higher range (>100 mg/L or >limit of solubility).

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

disregarded due to major methodological deficiencies

Study period:

Not reported

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The study did not include analysis of the test media and details on the test media preparation. Moreover, relevant information are missing in order to check if the validity criteria according to todays standard methods are met. Thus, the study is not considered to be reliable and was not considered for the assessment.

Qualifier:

according to guideline

Guideline:

other: ASTM E729-80 (1980), US EPA 660/3-75-009 (1975)

GLP compliance:

not specified

Analytical monitoring:

no

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: Test media were prepared in reconstituted freshwater using acetone as a solvent.

- Controls: Dilution water + acetone

- Chemical name of vehicle (organic solvent, emulsifier or dispersant): acetone (2 propanone)

- Concentration of vehicle in test medium (stock solution and final test solution): (75μl/150 mL)

Test organisms (species):

Daphnia pulex

Details on test organisms:

TEST ORGANISM

- Source: Laboratory stock cultures maintained in accordance with the test guidelines

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

- Feeding during test: none


ACCLIMATION

- Acclimation period: no data

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

- Type and amount of food: A mixture of four species of algae combined with a cerophyl infusion at a volume ratio of 1:1:1:1:1:4. The average cell densities of the algae in the final culture medium were Chlorella vulgaris at 3400 cells/mL, Chlorella pyrenoidosa at 1300 cells/mL, Ankistrodesmus falcatus at 3000 cells/mL and Chlamydomonas reinhardi at 1200 cells/mL)

- Feeding frequency: not reported

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

Hard water

Test temperature:

17ºC

pH:

no data

Dissolved oxygen:

no data

Salinity:

not applicable

Nominal and measured concentrations:

Control (with acetone) and five nominal concentrations separated by a factor of 1.7

Details on test conditions:

TEST SYSTEM

- Test vessel: Beaker

- Type: no data

- Fill volume: 150 mL

- Aeration: no data

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

- No. of organisms per vessel: 10

- No. of vessels per concentration (replicates): 2

- No. of vessels per vehicle control (replicates): 2

- Biomass loading rate: 1 daphnid/15 mL of test medium


TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: Reconstituted freshwater

- Culture medium different from test medium: no

- Intervals of water quality measurement: no data


OTHER TEST CONDITIONS

- Adjustment of pH: no data

- Photoperiod: no data

- Light intensity: no data


EFFECT PARAMETERS MEASURED (with observation intervals if applicable): mobility after 48 hours


TEST CONCENTRATIONS

- Spacing factor for test concentrations: 1.7

- Range finding study: no data

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

ca. 0.04 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:

EC50

Effect conc.:

1.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

but exposure is to hydrolysis products

Basis for effect:

mobility

Details on results:

- Control immobilisation: no data

Reported statistics and error estimates:

ECx values were calculated by Probit Analysis after Finney (1971)

Validity criteria fulfilled:

yes

Conclusions:

A 48-h EC50 value of 1.3 mg/L has been determined for the effects of the test substance on mobility of Daphnia pulex based on nominal concentrations of the substance. The study did not include analysis of the test media, details on the test media preparation as well as raw data on immobilisation in the treatments and controls. Moreover, relevant information are missing in order to check if the validity criteria according to todays standard methods are met. Thus, the study is not considered to be reliable and was not considered for the assessment. In addition, reliable and fully documented studies with substances that hydrolyse to the same hydrolysis report results in a much higher range (>100 mg/L or >limit of solubility).

Reference 3

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2008-06-30 to 2008-07-25

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Measurement of the test article concentrations were performed on the batch preparation of each test solution at test initiation. At test termination, water samples were collected for analysis from each test chamber. Water samples (10 mL) were collected from mid- depth of the test chambers using a glass pipette.

- Sampling method: At test termination, water samples were collected for analysis from each test chamber. Water samples (10 mL) were collected from mid- depth of the test chambers using a glass pipette.

Vehicle:

no

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM

- Source: Daphnia magna used in this study were obtained from in-house cultures. The original source of the brood stock was Aquatic BioSystems, Fort Collins, Colorado.

- Age at study initiation: <24 hours

- Feeding during test: Daphnia magna were not fed during the test.


ACCLIMATION

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

- Type and amount of food: Daphnia magna cultures were fed a diet of Selenastrum capricornutum and YCT (yeast, cerophyl and trout chow).
- Feeding frequency:

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

103 mg/L as CaCO3

Test temperature:

20+/-2ºC

pH:

7.4-8.2

Dissolved oxygen:

≥7.5 mg/L (85% of saturation)

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal concentrations: 0 (Control) and 120 mg/L

Measured concentration at test initiation: 116 mg/L

Measured concentrations at test termination: 120 mg/L

Mean measured concentration: 117 mg/L (99% of the nominal)

Details on test conditions:

TEST SYSTEM

- Test vessels: 600 mL glass beakers containing approximately 500 mL of test solution. Test vessels were impartially placed in an environmental chamber set to maintain a temperature of 20  1C. Each test vessel was covered with a watch glass to reduce evaporation. Test vessels were labeled with the study number, test article concentration and replicate.

- Treatments and replication: Daphnia magna were exposed to one limit concentration of the test article and a negative (dilution water) control. Two replicate test chambers were maintained in each treatment group, with 10 Daphnia magna in each test vessel for a total of 20 Daphnia magna per treatment. The nominal test concentration was selected based on an exploratory range-finding test. The nominal test concentration was 120 mg dimethylsilanediol/L (mg/L). Water samples were collected at test initiation and at test termination for measurement of the test article. Mean measured concentrations were used to estimate EC50 values.

Daphnia magna were indiscriminately assigned to test chambers at test initiation. Indiscriminate distribution was achieved by sequentially adding one to two daphnids at a time to test vessels until each contained 10 daphnids. All transfers were made under the surface of the water. Observations of mortality/immobility and sublethal effects were made at test initiation and approximately 24 and 48 hours after test initiation. Cumulative percent mortality/immobility observed in the treatment group was used to estimate EC50 values at 24 and 48 hours.

- Dilution water: The dilution water was municipal water obtained from Bay City, Michigan. The municipal water was dechlorinated using a carbon filter and aerated prior to use. The pH of the water is periodically adjusted using CO2, as necessary. The water is monitored weekly for hardness, alkalinity, conductivity, pH and total residual chlorine (TRC). The municipal water is also monitored once a year for selected inorganics, total suspended solids (TSS), total organic carbon (TOC) and selected organic compounds. No contaminants have been shown to be present in the municipal water at concentrations that might affect the outcome of this study.

- Environmental conditions: Lighting used to illuminate the test chambers was provided by cool white fluorescent bulbs with a photoperiod of 16 hours light and 8 hours dark. Temperature, dissolved oxygen and pH were measured in the batch solutions prepared at test initiation and in each test vessel at approximately 48 hours. Temperature was measured using a liquid-in-glass thermometer. In addition, temperature of the environmental chamber was measured continuously. The target test temperature was 20+/-2ºC. Measurements of dissolved oxygen were made using a Yellow Springs Instruments dissolved oxygen meter and measurements of pH were made using an Orion pH meter. A sample of dilution water was collected at test initiation for measurements of hardness, alkalinity, conductivity and TRC. Hardness and alkalinity were measured by titration. Conductivity was measured using a Yellow Springs Instruments salinity, conductivity and temperature meter. TRC was measured using a Fisher Chlorine Titrimeter 397.

- Observations: Observations were made to evaluate the number of mortalities and immobile organisms. Immobility was defined as the lack of swimming within 15 seconds after gentle agitation of the test vessel. The numbers of organisms exhibiting sublethal effects (e.g., lethargy, discoloration, etc.) were also evaluated. Observations were made at test initiation and 24 and 48 hours after test initiation (+/-1 hour).

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 117 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

>= 117 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Immobilisation in control: 0

Reported statistics and error estimates:

The EC50 values were estimated by visual inspection of the mortality/immobility data. Confidence limits could not be calculated because only one concentration was tested.

Daphnia magna in the negative control appeared normal and healthy throughout the test with no mortality/immobility or overt signs of toxicity. After 48 hours of exposure, Daphnia magna exposed to dimethylsilanediol at a concentration of 119 mg/L also appeared normal and healthy with no mortality or immobility. 

Validity criteria fulfilled:

yes

Conclusions:

A 48-hour EC50 value of >117 mg/L and NOEC of ≥117 mg/L have been determined for the effects of the test substance on mobility of Daphnia magna.

Reference 4

Endpoint:

short-term toxicity to aquatic invertebrates

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 the attached justification below and the overall justification for grouping of substances attached in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across source

Salinity:

Not applicable

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 117 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

>= 117 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Description of key information

EC50 (48 h) > 117 mg/L (measured (arithmetic mean), OECD 202)

Additional information

There are no data available on short-term toxicity to aquatic invertebrates for Diethoxy(dimethyl)silane (CAS 78-62-6). In accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5 “Grouping of substances and read-across” and in accordance with the read across assessment framework (RAAF, ECHA 2017) a read-across from the analogue substance dimethylsilanediol (CAS 1066-42-8) has been applied to support the environmental hazard assessment of diethoxy(dimethyl)silane (CAS 78-62-6). Details on the read across justification can be found in the attached justification in the respective target entry and in the overall justification for grouping of substances attached in IUCLID Section 13.

The study with the analogue substance dimethylsilanediol (CAS 1066-42-8) was performed according to OECD 202 (GLP). Daphnia magna was exposed to the substance in a limit test to a test item concentration of 120 mg/L (nominal) and a control under static conditions. The test concentration remained stable for the duration of the study resulting in a mean measured test concentration of 117 mg/L. No immobilisation was recorded after 48 h resulting in an EC50 (48 h) > 117 mg/L.
Two publications performed with the target substance itself are additionally available which were disregarded. The studies were not conducted according to GLP and have a limited documentation with regard to the test performance. No information are given on immobilization at each concentration (incl. control) over time, limited information on physico-chemical properties of the test medium (e.g. O2-concentration, pH) are available and both studies did not include analysis of the test media and details on the test media preparation. Based on the limited information available the validity criteria of today’s standard methods cannot be verified and the results from the publications are not considered to be reliable. Since there is a high level of uncertainty regarding the correct test performance the derived EC50 (48 h) value of 1.3 mg/L and 2.1 mg/L (mobility, Daphnia pulex) were not considered for the assessment of the substance. In contrast, a reliable and fully documented study from the hydrolysis product resulted in no effects to aquatic invertebrates. Based on the result of the analogue substance (hydrolysis product), Diethoxy(dimethyl)silane (CAS 78-62-6) is not assumed to be harmful to aquatic invertebrates.