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EC number: 240-914-9 | CAS number: 16881-77-9
- 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:
- read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- key study
- Justification for type of information:
- Please refer to the analogue approach justification provided in Section 13.
- Reason / purpose for cross-reference:
- read-across source
- 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
- 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
Description of key information
ErC50 (72 h) > 120 mg/L (nominal, OECD 201, R. subcapitata; read-across CAS No. 1185-55-3), equivalent to 83 mg/L when expressed in terms of the silanol hydrolysis product methylsilanetriol
NOErC (72 h) ≥ 120 mg/L (nominal, OECD 201, R. subcapitata; read-across CAS No. 1185-55-3), equivalent to 83 mg/L when expressed in terms of the silanol hydrolysis product methylsilanetriol
Key value for chemical safety assessment
- EC50 for freshwater algae:
- 83 mg/L
- EC10 or NOEC for freshwater algae:
- 83 mg/L
Additional information
The registered substance dimethoxy(methyl)silane (CAS No. 16881-77-9) hydrolyses rapidly (DT50 = 0.3 h) to the silanol hydrolysis products methylsilanediol and methylsilanetriol and the alcohol hydrolysis product methanol.
The ECHA guidance R.16 states that “for substances where hydrolytic DT50 is less than 12 h, environmental effects are likely to be attributed to the hydrolysis product rather than to the parent itself” (ECHA, 2016). The TGD (EC2003) and ECHA guidance R.16 (ECHA 2010) also suggests that in case the hydrolysis half-life is less than 12 h, the breakdown products, rather than the parent substance, should be evaluated for aquatic toxicity.
It is anticipated that the second silanol hydrolysis product, methylsilanetriol, is the final product of the
hydrolysis reactions and is thus considered the relevant assessment entity for the present Chemical Safety Assessment according to REACH.
Thus, the environmental fate assessment as well as the hazard and risk assessment are based on the
hydrolysis products methylsilanetriol and methanol rather than the parent substance.
Methanol is known for its absence of environmental toxicity at the concentrations relevant to this dossier (OECD SIDS, 2004), and is therefore not considered contributory to the overall aquatic toxicity of the substance and thus not relevant for the assessment of aquatic toxicity.
For the toxicity to aquatic algae, no experimental data are available for the registered substance itself. Therefore, read-across was performed from the structurally similar analogue substance trimethoxy(methyl)silane (CAS No. 1185-55-3), which hydrolyses within a comparable time frame (DT50 = 2.2 h) to the same silanol hydrolysis product methylsilanetriol, which the target and source substances thus share in common. A detailed read-across justification is provided in IUCLID Section 13.
The available read-across study was carried out according to the testing guideline OECD 201 and in compliance with GLP.
In a static test, R. subcapitata were exposed to 5 concentration levels up to 120 mg/L (nominal) for 72 h. Test concentrations were prepared by direct application to test medium. No vehicle was used. Test concentrations were analytically monitored by GC-MS at test start and test end.
After 72 h, an ErC50 (72 h) of > 3.6 mg/L (measured), corresponding to > 120 mg/L (nominal) as well as a NOErC (72 h) of ≥ 3.6 mg/L (measured), corresponding to ≥ 120 mg/L (nominal) were determined.
In view of the fast hydrolysis rate of the substance and the applied methodology (i.e. test design, test medium preparation) it is likely that the test organisms were predominantly exposed to the hydrolysis products of the tested substance. This is reflected in the low measured concentrations of the parent substance. Effect concentrations are therefore reported in terms of the nominal concentration.
The results may be expressed in terms of the silanol hydrolysis product methylsilanetriol (CAS No. 2445-53-6; EC No. 219-489-9), by application of a correction factor for molecular weight (MW of silanol = 94.14 / MW of parent = 136.22), resulting in ≥ 83 mg/L (based on nominal) and > 2.5 mg/L (based on measured concentration).
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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