Trimethoxyoctylsilane

Toxicity to soil macroorganisms except arthropods

Administrative data

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009-10-01 to 2009-10-05

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

Analytical monitoring:

no

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: A dosing stock solution was prepared by mixing 1.87 mL (density 1.07 g/mL) of Trichloro(2,4,4-trimethylpentyl)silane (corresponding to 2 g) with 2.0 mL of tetrahydrofuran (THF) using a Hamilton syringe. The 100 mg test item/L test solution was prepared prior to test initiation by adding 0.485 mL of the dosing stock solution to approximately 1.7 to 1.8 L dilution water using a Hamilton syringe. Prior to addition of the dosing stock solution, the glass beaker containing the dilution water was placed on a magnetic stirrer. This procedure was repeated three times and the resulting solutions combined. The spiked solution was stirred continuously over night. The pH of the solution was then adjusted to 7.0 with 1 N sodium
hydroxide (NaOH). Thereafter, the test solution was further diluted to a final volume of 10 L with dilution water, resulting in a solvent (THF) concentration of 0.10 mL/L. The resulting test solution was mixed for 30 seconds using a glass rod and observed to be clear and colourless, with no visible undissolved test item.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM

- Source: The trout were originally obtained from Forellenzucht P. Hohler-Gasser, a commercial supplier located in Zeiningen, Switzerland.

- Length at study initiation (length definition, mean, range and SD): 34 mm (range 29 to 39 mm)

- Weight at study initiation (mean and range, SD): 0.42 g (range 0.20 to 0.63 g)

- Feeding during test: Fish were not fed during the 24-hour period prior to test initiation and during the exposure period.


ACCLIMATION

- Acclimation conditions (same as test or not): Prior to testing, the fish were maintained in a holding tank (under renewal conditions) under a photoperiod of 16 hours light and 8 hours darkness with a 30 minute transition period. The culture water was modified well water from the municipality of Horn, deionized with a Culligan Reverse Osmosis system. The deionized well water was reconstituted according to the formulation given in the Official Journal of the European Communities.

- Feeding: The fish were fed Hokovit 502, a dry, commercially available food, generally once daily.

- Health during acclimation (any mortality observed): No mortality was observed among the test fish population during the 12-day period prior to testing.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Hardness:

160 mg/L as CaCO3

Test temperature:

14.7 to 15.9 °C

pH:

7.04 to 7.65

Dissolved oxygen:

8.43 to 10.43 mg/L

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal concentrations: 0 (Control), 0 (Solvent control) and 100 mg/L

Details on test conditions:

TEST SYSTEM

- Test vessel: The test vessels were 12.5 L vessels constructed of stainless steel, each containing 10 L of test solution. The test vessels were placed in a water bath in order to maintain exposure solution temperatures at 15 ± 2°C. The test vessels were loosely covered with a glass plate during the 96-hour exposure.

- Aeration: Test solutions were gently aerated (with oil-free air) throughout the duration of the exposure period.

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

- No. of organisms per vessel: 7

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

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

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

- Biomass loading rate: 0.3 g of biomass per litre of test solution


TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: The dilution water used during the definitive test had a pH of 7.64, a total hardness and alkalinity as CaCO3 of 160 and 26 mg/L, respectively, and a specific conductivity of 400 μS/cm.

- Culture medium different from test medium: No

- Intervals of water quality measurement: The pH, dissolved oxygen concentration and temperature were measured at 0, 24, 48, 72 and 96 hours in each test solution. Continuous temperature monitoring was performed in the control solution throughout the exposure period.


OTHER TEST CONDITIONS

- Photoperiod: A 16-hour light, 8-hour dark photoperiod was maintained with an automatic timer.

- Light intensity: The test was illuminated to a light intensity of 200 to 500 lux using fluorescent bulbs.


EFFECT PARAMETERS MEASURED: All test vessels were examined at 0, 24, 48, 72 and 96 hours of exposure for mortality. In addition observations of the physical characteristics of the test solutions (e.g., clear solution, precipitate, film on the surface of the test solution) were made and recorded at each 24-hour interval. Biological observations, including adverse effects on the exposed trout, were performed and recorded at each 24-hour interval. Effects for this study were based on mortality, defined as the lack of movement by the exposed organisms (i.e., absence of gill movement and reaction to gentle prodding).

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

but predominantly exposed to hydrolysis product

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

but predominantly exposed to hydrolysis product

Basis for effect:

mortality (fish)

Details on results:

- Behavioural abnormalities: 0

- Mortality of control: 0

- Other adverse effects control: 0

- Abnormal responses: 0

Reported statistics and error estimates:

Since no 50% mortality was observed during the 96 hours of exposure, no 24-, 48-, 72- and 96-hour median lethal concentrations (LC50) were calculated. Based on the nature of the raw data, the LC50 values were empirically estimated as > 100 mg test item/L.

The No-Observed-Effect Concentration (NOEC) during the 96-hour exposure period was determined by visual observation. The NOEC is defined as the highest concentration tested at and below which there were no toxicant-related effects and mortality with respect to the control
organisms.

Sublethal observations / clinical signs:

There were no effects on mortality in the Controls or in the 100 mg/L nominal treatment.

Validity criteria fulfilled:

yes

Conclusions:

A 96-h LC50 value of >100 mg/L and NOEC of ≥100 mg/L have been determined for the effects of the substance on mortality of Oncorhynchus mykiss based on nominal concentration. It is likely that the test organisms were solely exposed to the hydrolysis products of the substance.

Cross-reference 2

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009-09-29 to 2009-10-02

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: Prior to test solution preparation, a dosing stock solution was prepared by mixing 1.52 mL of Trichloro(phenyl)silane (corresponding to 2 g) with 2 mL of tetrahydrofuran (THF) using Hamilton syringes. The solution was shaken by hand. A 100 mg test item/L stock solution
was prepared prior to test initiation by adding 176 μL of the dosing stock solution to 800 mL algal medium using a Hamilton syringe. Prior to addition of the dosing stock solution, the measurement flask containing the algal medium was placed on a magnetic stirrer. The spiked solution was stirred continuously over night. The pH of the solution was then adjusted to 7.0 with 0.1 N sodium hydroxide (NaOH). Thereafter, the stock solution was further diluted to a final volume of 1000 mL with algal medium, resulting in a solvent (THF) concentration of 0.10 mL/L. Nominal test concentrations of 6.25, 12.5, 25, 50 and 100 mg/L were prepared by dilution of the stock solution and addition of THF to a final concentration of 0.1 mL/L. All resulting test solutions were shaken by hand for 30 seconds and observed to be clear and colourless, with no visible undissolved test item.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM

- Source (laboratory, culture collection): The alga was originally obtained from Albrecht-v.-Haller-Institut, Göttingen, Germany, and was maintained in stock culture at Springborn Smithers Laboratories (Europe).

- Culture medium: The culture medium used was a synthetic algal assay growth medium (OECD, 2006), prepared by adding appropriate amounts of nutrient stock solutions to sterile, deionized water. Representative samples of the dilution water source used in the preparation of the culture medium were analysed periodically for the presence of pesticides, PCBs and toxic metals conducted at Bachema, Schlieren, and Interlabor Belp AG, Belp, Switzerland. None of these compounds have been detected at concentrations that are considered toxic to algae in any of the water samples analysed in agreement with ASTM guidelines.

- Preparation of starter culture: Four days prior to test start, the culture was maintained within the following conditions: a shaking rate of 120 rpm, a temperature of 23ºC and continuous illumination of 7091 to 7123 lux. Lighting was supplied by fluorescent bulbs. Culture flasks were shaken
continuously on an orbital shaker. Temperature was controlled using an environmental chamber. The inoculum used to initiate the toxicity test was taken from a stock culture that had been transferred to fresh medium four days before testing.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

Not reported

Test temperature:

23.4 to 23.7ºC

pH:

7.30 to 7.65 at test initiation

6.08 to 9.86 at end of test

Dissolved oxygen:

Not reported

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal test concentrations: 0 (Control), 0 (Solvent control), 6.25, 12.5, 25.0, 50.0 and 100 mg test item/L

Details on test conditions:

TEST SYSTEM

Test vessels: Three sterile 250-mL Erlenmeyer flasks (A to C) for the controls and the treatment levels were prepared. An aliquot of 100 mL of the appropriate test solution was placed in each replicate flask. All test vessels were fitted with stainless steel caps which permitted gas exchange.

- Inoculum: An aliquot of 0.25 mL of the preculture of Pseudokirchneriella subcapitata, at a density of 394 x 104 cells/mL, was then inoculated aseptically in each 250 mL volumetric flask. The resulting slight dilution from the inoculum was considered to be negligible. These volumes of inocula provided the required cell density of 1.0 x 104 cells/mL.

- Algal growth medium: The algal medium used to prepare the exposure solutions was the same as the culture medium. The medium was equilibrated to test temperature. The pH of the medium was 8.03.

- Test conditions: The test was conducted in a temperature-controlled room to maintain the test conditions specified in the study plan: a temperature of 24 ± 2ºC and continuous light intensity of 4400 to 8800 lux. An orbital shaker table provided a shaking rate of 100 rpm. Test flasks were randomly placed on the shaker table at test initiation. Following each observation interval the test flasks were assigned new random positions.

- Algal growth measurement: At each subsequent 24-hour interval, cell counts were conducted on each replicate vessel of the treatment levels and the control using a hemocytometer (Neubauer Improved) and a Leica DMLS microscope. One sample was removed from each flask for counting. One or more hemocytometer field(s), each 0.1 cm x 0.1 cm in size and 0.01 cm deep, containing 0.0001 mL of culture, were examined for each sample until at least 400 cells or a total of four fields were counted. Observations of the health of the algal cells were also made at each 24- hour interval.

- Monitoring culture conditions: Temperature was measured continuously with a minimum/maximum thermometer located in a flask of water adjacent to the test flasks in the environmental chamber. Minimum and maximum temperatures and the shaking rate of the orbital shakers (Gerhardt, 450625 R05) were recorded daily. Light intensity was measured with a Pancontrol LX 1308 at hour 0 and at each 24-hour interval during the exposure period. The pH of the test solutions and control was measured at test initiation and at the termination of the 72-hour exposure period. Test solution pH was measured using a Metrohm 691 pH-meter.

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

- Exponential growth in the control (for algal test): yes

Reported statistics and error estimates:

Definitive EC50 values could not be determined because they were above the highest treatment level.

ANOVA and William’s Test were used to determine the NOEC and LOEC values

Table 1. Test results

Nominal test concentration (mg/L)	Initial cell density (cells/mL)	Mean cell density after 24 hours (cell/mL)	Mean cell density after 48 hours (cell/mL)	Mean cell density after 72 hours (cell/mL)	Perecntage inhibition in cell density*	Percentage inhibition in growth rate*	Percentage inhibition in biomass*
0 (Control)	10000	48000	247000	1070000	9.0	1.4	9.0
0 (Solvent control)	10000	59000	228000	1180000	-	-	-
6.25	10000	65000	279000	1240000	-5.3	-1.9	-5.4
12.5	10000	49000	254000	1140000	2.7	-0.03	2.7
25.0	10000	43000	240000	1050000	10.5	1.9	10.6
50.0	10000	33000	203000	1030000	12.6	2.0	12.7
100	10000	45000	248000	1030000	12.1	2.2	12.2

*Relative to solvent control. A negative (-) value indicates that growth was higher than in the solvent control.

Validity criteria fulfilled:

yes

Conclusions:

A 72-hour EC50 value of >100 mg/L and a NOEC of ≥100 mg/L have been determined for the effects of the test substance on growth rate and biomass of Pseudokirchneriella subcapitata. It is likely that the test organisms were solely exposed to the hydrolysis products of the substance.

Cross-reference 3

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009-04-07 to 2009-04-29

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

The study was conducted according to an appropriate OECD test guideline and according to GLP, with acceptable restrictions. The restrictions were that the analytical monitoring was carried out in the form of TOC. This method of analysis is non-specific, therefore it is not possible to determine what form of the substance was tested. In addition some undissolved test material was present and the stock solution preparation was not ideal for this substance, which is expected to polymerise at concentrations of around 200 mg/l and above.

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Sampling method: Duplicate samples were taken from the freshly prepared test media of the loading rate of 100 mg/L and the control at the start of every test interval. In addition, duplicate samples were taken from the freshly prepared (Days 0, 2, 5 and 7) and aged test media (Days 2, 5 and 7) of all test concentrations and from the control at three test intervals. The aged samples were stored without food and test animals, but were incubated during the renewal periods under test conditions.

- Sample storage conditions before analysis: All samples were analysed immediately after the sampling.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: A dispersion of the test item with the loading rate of 100 mg/L was prepared by adding 300 mg of the test item (dosed by pipetting 300 μL of the test item) into a beaker partially filled with test water under intense stirring. No auxiliary solvent or emulsifier was used. After addition of the test item, the beaker was filled up with test water to the volume of 3000 mL and the test item was mixed into the test water as homogeneously as possible using ultrasonic treatment (15 minutes). The pH was adjusted from 3.0 to 7.9 (± 0.3). Thereafter, the dispersion was stirred on a magnetic stirrer at room temperature over 24 hours in the dark. The stirring period of the dispersion was chosen according to the results of a pre-experiment.

Following the stirring period of 24 hours, the test medium was incubated in the dark for an equilibration period of one hour to allow any undissolved reaction products to float at the surface of the test solution or to settle on the bottom. The test water (containing the water dissolvable hydrolysis products) was taken from the middle of the water column to avoid any undissolved test item/hydrolysis products in the test water.

This test water was used as the highest concentrated test medium and as the stock solution for lower concentrated test media. Requisite aliquots were diluted with test water to obtain the additional test concentrations.

The test media were freshly prepared before the start of the test and before each test medium renewal.

- Controls: Dilution water

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM

- Strain/clone: Clone 5

- Source: University of Sheffield/UK

- Age of parental stock (mean and range, SD): The daphnids used for the test originated from parental daphnids that were at least 14 days old but not older than four weeks and were not first brood progeny. At the start of the test, the test animals were less than 24 hours old.

- Feeding during test: The test animals were fed daily with a food mixture containing a suspension of green algae of the species Scenedesmus subspicatus (freshly grown at Harlan Laboratories) and a fish food suspension.

The fish food suspension was prepared by dispersing 10 g of powdered commercial fish diet (TETRA MIN Hauptfutter, obtained from TETRA-Werke, 49304 Melle / Germany) in 500 mL of test water. The suspension was allowed to stand for 4 hours. Then, 400 mL of the supernatant were taken, diluted 1:1 with test water and boiled. The suspension was stored deep frozen in small quantities until use.

The carbon contents of the algal and fish food suspensions were determined using a Shimadzu TOC 5000A Analyzer. The food amount (based on the measured concentrations of the total organic carbon (TOC) in the food suspensions) was 0.20 mg TOC per Daphnia and day.


ACCLIMATION

- Acclimation conditions (same as test or not): The temperature and light conditions were identical to those of the test.

- Feeding frequency: The animals were fed normally three times a week with green algae of the species Scenedesmus subspicatus and with a fish food suspension.

- Health during acclimation (any mortality observed): No signs of stress were observed and the brood stock was healthy.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Hardness:

250 mg/L as CaCO3

Test temperature:

20-21°C

pH:

7.5-8.0

Dissolved oxygen:

≥7.2 mg/L

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal concentrations: 0 (Control), 100 mg/L and dilutions of 1:2.16, 1:4.7, 1:10 and 1:22.

Mean initial measured concentrations in the treated media: 65, 32, 14, 6.7 and 3.1 mg/L

At the start of the renewal periods the concentrations of the test item measured in the test medium of all tested concentrations (based on the TOC) were between 41 and 76% of the nominal concentrations. At the end of the three measured renewal periods the concentrations were between 62 and 85% (test media without food). Thus, the TOC content of the tested concentrations was sufficiently stable during the test medium renewal periods of two and three days. All reported biological results are related to the initially mean measured concentrations of the test item.

Details on test conditions:

TEST SYSTEM

- Test vessel: The test was performed in 100-mL glass beakers containing 80 mL of test medium. The test vessels were covered with glass plates to reduce the loss of water by evaporation and to avoid the entry of dust into the solutions.

- Replication: The study was started with 10 daphnids per treatment. Each test animal was kept individually in a glass beaker. The test animals were randomly distributed to the test vessels. The test duration was 21 days.

- Test medium renewal: The test media of all treatments were renewed on Days 2, 5, 7, 9, 12, 14, 16, and 19 of the test period (every Monday, Wednesday, and Friday). At these dates, the surviving test animals were carefully transferred by means of glass tubes into test vessels containing freshly prepared test medium.

- Lighting: A 16-hour light to 8-hour dark cycle with a 30 minute transition period was used. Light intensity during the light period was between approximately 520 and 680 Lux.

- Observations: The test replicates were observed for mortality of adults on Days 0-2 and thereafter three times per week before renewal of the test media. On the same dates, the test replicates were observed for live and dead offspring and for the presence of aborted eggs.

- Calculations: The reproduction rate was calculated as the total number of living offspring produced per parent female surviving until the end of the test.

- Water quality: At the beginning and end of each test medium renewal period, the pH and dissolved oxygen concentrations were measured in one replicate of each test concentration and of the control. At the same time, the water temperature was measured in one of the control replicates. Additionally, the room temperature was continuously monitored. The appearance of the test media was visually inspected and recorded at the beginning and end of each test medium renewal period.

- Selection of test concentrations: test concentrations were selected on the basis of the results of a non-GLP range-finding test (results not reported)

Reference substance (positive control):

no

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

32 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: Mean initial measured concentration of Total Organic Carbon expressed as equivalent test substance concentration

Basis for effect:

mortality

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

65 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: Mean initial measured concentration of Total Organic Carbon expressed as equivalent test substance concentration

Basis for effect:

mortality

Details on results:

- Control mortality: 0%

- Other biological observations: With the exception of the reported mortality, no visible abnormalities were observed at the test animals during the test. No EC values for the inhibition of the reproduction rate could be calculated since no effect was determined on the reproduction of the daphnids at all test concentrations with surviving parent animals.

Reported statistics and error estimates:

The mean reproduction rates of the daphnids at the test concentrations were compared to the control by multiple Williams’ tests

Table 1. Results of analysis of test media

Nominal treatment	Nominal concentration (mg/L)	Mean measured initial concentration (mg/L)	Percentage of nominal	n
0 (Control)	0	-	-	-
1:22 dilution of stock	4.5	3.1	68	4
1:10 dilution of stock	10	6.7	67	4
1:4.7 dilution of stock	21	14	68	4
1:2.16 dilution of stock	46	32	69	4
100 mg/L stock	100	65	65	9

Table 2. Test results

Mean initial measured concentration (mg/L)	Percentage mortality after 21 days	Day of first offspring release	Mean reproduction rate (live young per surviving adult)	Mean reproduction rate as a percentage of control
0 (Control)	0	9	89.8	-
3.1	20	7	86.1	96
6.7	10	7	92.4	103
14	10	9	84.3	94
32	20	9	82.5	92
65	100	7	Not applicable (all parents dead)	-

Validity criteria fulfilled:

yes

Conclusions:

A 21-day NOEC of 32 mg/L and a LOEC of 65 mg/L have been determined for the effects of the test substance on mortality of Daphnia magna. No effects on reproduction were determined in test concentrations below the LOEC for mortality. The report authors note that it cannot be excluded that the effects of the test item were at least partly caused by undissolved test item, which could not be removed by the preparation method used during the test period. It is likely that the test organism were primarily exposed to the hydrolysis products and polymerised forms of the substance.

Cross-reference 4

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Adsorption/desorption:

log Koc [trimethoxy(octyl)silane]: not relevant due to rapid hydrolysis of the substance in contact with water

 

log Koc [octylsilanetriol]: 1.6 (calculation)

The substance hydrolyses rapidly to substances which have low log K_ow values (<3) and thus has low potential for adsorption, and the requirement for testing is waived.

For environmental exposure assessment, adsorption is predicted for the silanol hydrolysis product using the ‘non-hydrophobics’ log K_ow-based prediction method for log K_oc developed by Sabljić and Güsten (1995) for the European Commission and recommended in EU Guidance.

The relevant equation is:

Log K_oc = 0.52 log K_ow + 1.02

Therefore, log K_oc for silanol hydrolysis product, octylsilanetriol = 1.6

Reference:

Sabljić A and Güsten H (1995). QSARs for soil sorption. in: overview of structure-activity relationships for environmental endpoints. Hermens JLM (ed), report prepared within the framework of the project "QSAR for prediction of fate and effects of chemicals in the environment", an international project of the Environmental Technologies RTD programme (DG XII/D-1) of the European Commission under contract number EV5V-CT92-0211.

Cross-reference 5

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

partition coefficient

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

See attached QMRF/QPRF

Principles of method if other than guideline:

The result was obtained using an appropriate QSAR method (see attached QMRF and QPRF for details).

The model is the publicly available KOWWIN v1.68 program (USEPA 2011). KOWWIN is part of EPI Suite v4.1 and may be downloaded from http://www.epa.gov/oppt/exposure/pubs/episuite.htm. The model is based on fragment values. That is, the chemical structure is broken down into its constituent functional groups, and the contribution of each group toward the overall partition coefficient is calculated. The constants used within KOWWIN have been derived by SRC from a wide range of organic chemicals. The authors of this QMRF have carried out additional validation and found the method to be applicable to organosilicon compounds, excluding di- and tri-alkoxysilanes.

USEPA 2011. KOWWIN v. 1.68, US EPA. 2011. Estimation Programs Interface Suite™ for Microsoft® Windows, v 4.10. United States Environmental Protection Agency, Washington, DC, USA. Available at http://www.epa.gov/oppt/exposure/pubs/episuite.htm.

Partition coefficient type:

octanol-water

Type:

log Pow

Partition coefficient:

1.1

Temp.:

20 °C

pH:

7

Conclusions:

A log Kow value of 1.1 was obtained for octylsilanetriol, using an appropriate calculation method. The result is considered to be reliable.

Materials and methods

Test material

Test material information

Constituent 1

Reference substance name:

Trimethoxyoctylsilane

EC Number:

221-338-7

EC Name:

Trimethoxyoctylsilane

Cas Number:

3069-40-7

Molecular formula:

C11H26O3Si

IUPAC Name:

trimethoxyoctylsilane