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EC number: 214-685-0 | CAS number: 1185-55-3
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Toxicity to aquatic algae and cyanobacteria
Administrative data
Link to relevant study record(s)
- Endpoint:
- toxicity to aquatic algae and cyanobacteria
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 2007-04-16 to 2007-05-10
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Remarks:
- Guideline study. This was a GLP compliant study with measured test concentrations
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 201 (Alga, Growth Inhibition Test)
- GLP compliance:
- yes
- Analytical monitoring:
- yes
- Details on sampling:
- - Sampling method: Test Concentrations were measured in each treatment at test initiation and at test termination
- Vehicle:
- no
- Details on test solutions:
- PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Stock solutions were prepared by direct addition of test article to algal assay medium - Test organisms (species):
- Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)
- Details on test organisms:
- - Species/strain # and source: Pseudokirchneriella subcapitata/Strain UTEX 1648, from in-house cultures initiated from cultures originally supplied by the University of Texas at Austin.
- Initial Density 10,000 cells/mL - Test type:
- static
- Water media type:
- freshwater
- Limit test:
- no
- Total exposure duration:
- 72 h
- Hardness:
- Not reported
- Test temperature:
- 24.0 to 24.4ºC
- pH:
- 7.6-7.7 at start of test
7.8-9.0 at end of test - Dissolved oxygen:
- Not reported
- Salinity:
- Not applicable
- Nominal and measured concentrations:
- Nominal concentrations: Negative Control, 7.5, 15, 30, 60 and 120 mg/L
Mean measured concentrations:
The large difference between nominal and mean measured exposure concentrations is attributed to the hydrolysis of the test substance under the static test conditions. The hydrolysis half-life of methyltrimethoxysilane is approximately 2.2 hours. All measured concentrations on Day 3 were less than the limit of quantitation (LOQ = 0.27 mg/L). Due to the decline in test concentrations during the test, mean measured concentrations were estimated as the geometric mean of Day 0 and Day 3 measured concentrations. The geometric mean concentrations were calculated using ½ LOQ for all Day 3 measurements (0.135 mg./L). - Details on test conditions:
- TEST SYSTEM
- Exposure vessel type: 250-mL Erlenmeyer flasks covered with a sponge closure containing 100 mL of test solution.
- Test Design: Three replicates for each treatment group. Five test concentrations and a negative control.
- Element basis (i.e. number of cells/ml, area under the curve, growth rate, etc.): Yield (Biomass) and Growth Rate "
- Growth/test medium chemistry: Algal Assay Medium (ASTM E 1218-04), pH 7.6
- Dilution water source: Distilled Water
- Water chemistry in test: Temperature was measured in the environmental chamber daily. Measurements of pH were made in each treatment group at test initiation and test termination.
- Light levels and quality during exposure: 490 to 626 foot-candles, continuous cool-white fluorescent lighting - Reference substance (positive control):
- no
- Duration:
- 72 h
- Dose descriptor:
- NOEC
- Effect conc.:
- >= 120 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- other: Growth Rate
- Duration:
- 72 h
- Dose descriptor:
- EC50
- Effect conc.:
- > 120 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- other: Yield (Biomass) and Growth Rate
- Duration:
- 72 h
- Dose descriptor:
- NOEC
- Effect conc.:
- >= 3.6 mg/L
- Nominal / measured:
- meas. (geom. mean)
- Conc. based on:
- test mat.
- Basis for effect:
- other: Growth Rate
- Duration:
- 72 h
- Dose descriptor:
- EC50
- Effect conc.:
- > 3.6 mg/L
- Nominal / measured:
- meas. (geom. mean)
- Conc. based on:
- test mat.
- Basis for effect:
- other: Yield (Biomass) and Growth Rate
- Details on results:
- - Exponential growth in the control (for algal test): yes
- Observations: Visual examination of algal cells at test termination showed no concentration-dependent changes in shape, color or size. - Reported statistics and error estimates:
- Statistical methods: Dunnett's test was used to determine if there were differences between Control and treatments.
- Validity criteria fulfilled:
- yes
- Conclusions:
- A 72-hour EC50 value of >3.6 mg/L and NOEC of ≥3.6 mg/L have been determined for the effects of the test substance on yield and growth rate of Pseudokirchneriella subcapitata based on geometric mean measured exposure concentrations of the test substance. The test substance is known to hydrolyse rapidly in water and 3.6 mg/L was the concentration measured in the highest nominal test concentration of 120 mg/L. It is therefore likely that the test organisms were predominantly exposed to the hydrolysis products of the substance.
Reference
Table 1. Test results
Nominal concentration (mg/L) |
Geometric mean measured concentration (mg/L) | Mean yield after 72 hours (cells/mL) | Percentage inhibition of yield | Mean growth rate 0 -72 hours | Percentage inhibition of growth rate |
Control | Control | 1098489 | - | 1.5692 | - |
7.5 | 0.77 | 1116978 | -1.7 | 1.5749 | -0.4 |
15 | 1.2 | 1112844 | -1.3 | 1.5737 | -0.3 |
30 | 1.7 | 1048378 | 4.6 | 1.5532 | 1.0 |
60 | 2.4 | 1080444 | 1.6 | 1.5635 | 0.4 |
120 | 3.6 | 1092800 | 0.5 | 1.5676 | 0.1 |
Description of key information
Toxicity to Algae: 72-hour EC50 >120 mg/l and NOEC ≥120 mg/l (nominal) (>3.6 and ≥ 3.6 mg/l, respectively, measured) (highest concentration tested) (OECD 201 (Alga, Growth Inhibition test)), effects of the test substance on growth rate of Pseudokirchneriella subcapitata. The EC50 is equivalent to >83 mg/l when expressed in terms of the silanol hydrolysis product.
Key value for chemical safety assessment
Additional information
A 72-hour EC50 value of >120 mg/l and NOEC of ≥120 mg/l (nominal) (>3.6 and ≥3.6 mg/l, respectively, measured) (highest concentration tested) have been determined for the effects of trimethoxy(methyl)silane (CAS 1185-55-3) on growth rate of Pseudokirchneriella subcapitata (Dow Corning Corporation 2007). The test was carried out in accordance with test guideline OECD 201 and in compliance with GLP.
The test substance is known to hydrolyse rapidly and, in view of the test media preparation method/exposure regime, it is likely that the test organisms were exposed predominantly to the hydrolysis products of the tested substance. This is reflected in the low measured parent substance concentrations. Effect concentrations are therefore reported in terms of the nominal concentration.
The results may be expressed in terms of concentration of the silanol hydrolysis product, methylsilanetriol (CAS 2445-53-6; EC No. 219-489-9), by applying a molecular weight correction: (MW of silanol = 94.14 / MW of parent = 136.22) * (concentration of parent = >120 (3.6 mg/l measured)) = >83 mg/l as methylsilanetriol, nominal concentration (>2.5 mg/l measured concentration).
The chemical safety assessment focuses on the silanol hydrolysis product methylsilanetriol. Due to the static testing regime, the algal data with the registered substance reflects exposure to the hydrolysis products. However, the short-term fish and Daphnia data with the registered substance reflect exposure to a mixture of parent substance and hydrolysis products. To support the chemical safety assessment of the hydrolysis product, data for fish and Daphnia have therefore been read across from triethoxy(methyl)silane (CAS 2031-67-6; EC No. 217-983-9) which rapidly hydrolyses to methylsilanetriol and the organisms in the tests were exposed to methylsilanetriol.
For consistency and to show that the read-across and registered substance test data are comparable, algal toxicity data with triethoxy(methyl)silane have also been read across. A 48-hour EC50 value of >500 mg/l and a NOEC value of ≥500 mg/l have been determined for the effects of triethoxy(methyl)silane on growth rate of Pseudokirchneriella subcapitata in a test carried out according to test guideline EU Method C.3 and in compliance with GLP (Hazelton, 1994).
In view of the test media preparation method/exposure regime it is likely that the test organisms were exposed predominantly to the hydrolysis products of the tested substance. The results may be expressed in terms of concentration of the hydrolysis product, methylsilanetriol, by applying a molecular weight correction: (MW of silanol = 94.14 / MW of parent = 178.31) * (CONCENTRATION OF PARENT = >500) = >264 mg/l as methylsilanetriol.
Refer to Section 6 endpoint summary, Section 7.0 of CSR, for further discussion of the approach to chemical safety assessment for this registration substance, and justification for read-across used.
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