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EC number: 240-816-6 | CAS number: 16753-62-1
- 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
Endpoint summary
Administrative data
Description of key information
Acute oral LD50 values of greater than 5000 mg/kg or 7120 for males and 7236 mg/kg for females were derived for read-across substances triethoxy(vinyl)silane and trimethoxy(vinyl)silane respectively.
The acute inhaled LC50 was greater than 5000 mg/m3 for the registered substance, dimethoxy(methyl)vinylsilane.
Key value for chemical safety assessment
Acute toxicity: via oral route
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed
- Dose descriptor:
- LD50
- Value:
- 5 000 mg/kg bw
Acute toxicity: via inhalation route
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed
- Dose descriptor:
- LC50
- Value:
- 5 000 mg/m³ air
Acute toxicity: via dermal route
Endpoint conclusion
- Endpoint conclusion:
- no study available
Additional information
No acute oral toxicity data are available for the registered substance. However, reliable data are available for related alkoxysilane substances and these are used as weight of evidence.
In an acute oral toxicity study with triethoxy(vinyl)silane (WIL, 1998) an LD50 in excess of 5000 mg/kg bw was identified. Five male and five female rats were treated by oral gavage with 3846 or 5000 mg/kg bw. At the higher dose 2/5 males and 1/5 females died, whereas at the lower dose 2/5 females were found dead. There was evidence of systemic toxicity at both doses including impaired muscle coordination, hypoactivity, tremors and clear ocular discharge. Mucoid faeces and laboured breathing were each noted for animals that died. All surviving animals appeared normal by day 13 of the observation period.
An acute oral toxicity study with trimethoxy(vinyl)silane (BRRC, 1984) gave LD50 values of 7.34 ml/kg and 7.46 ml/kg in male and female rats, respectively. Deaths were noted at 8 or 16 ml/kg and clinical signs included sluggishness, red to brown discharge, lacrimation, pilo-erection, unkempt appearance, prostration, emaciation and unsteady gait. At necropsy, dark red kidney sections were observed in animals that died at 16 and 8 ml/kg. There were no gross necropsy findings in animals that survived to the end of the study. On the basis of a measured relative density of 0.97, the reported LD50 values correspond to ca. 7120 and 7236 mg/kg for males and females respectively.
In the key inhaled acute study with the registered substance, dimethoxy(methyl)vinylsilane (DCC, 1996) there were no notable findings in animals exposed to 5 mg/L for 4 hours, therefore the LC50 was considered to be greater than 5000 mg/m3.
READ-ACROSS JUSTIFICATION
To reduce animal testing REACH recommends to make use of a read-across approach where appropriate based on the high accordance in properties relevant for the specific endpoint. In the case of acute toxicity relevant properties are structural similarity as well as physical-chemical and basic toxicological parameters in the same range. In the following paragraphs the proposed read-across from trimethoxy(vinyl)silane and triethoxy(vinyl)silane to dimethoxy(methyl)vinylsilane is evaluated point by point.
A report considering read across for all endpoints is attached in Section 13.
Read-across hypothesis
The hypothesis is that source and target substances have similar toxicological properties because they are structurally similar and hydrolyse to similar silicon-containing hydrolysis products. The non-silanol hydrolysis products, methanol and ethanol, do not contribute to any adverse effects for acute toxicity at the relevant dose levels based on publicly available information (OECD SIDS, 2004a and OECD 2004b). This is discussed further below.
Read-across justification
The predicted hydrolysis half-lives of the registered substance, dimethoxy(methyl)vinylsilane, are 18.3 minutes at pH 7, <2 minutes at pH 2, and 0.7 minutes at pH 9, all at 25oC; at 37.5oC and at pH 7 and 2 (relevant for conditions in the lung or stomach following inhaled or oral exposure) the predicted half-lives are 0.1 hours and 5 seconds respectively. The products of hydrolysis are methylvinylsilanediol and methanol.
The read-across substance triethoxy(vinyl)silane has predicted hydrolysis half-lives at 20-25°C of 0.1 hours at pH 4, 0.9 hours at pH 7 and 0.02 hours at pH 9. As the hydrolysis reaction may be acid or base catalysed, the rate of reaction is expected to be slowest at pH 7 and increase as the pH is raised or lowered. The hydrolysis half-life at 37.5ºC and pH 2 (relevant for conditions in the stomach following oral exposure) is approximately 5 seconds. The hydrolysis products are vinylsilanetriol and ethanol.
The read-across substance trimethoxy(vinyl)silane has predicted hydrolysis half-lives at 25°C of 0.1 hours at pH 7, 0.04 hours at pH 4, and 0.004 hours at pH 9. The hydrolysis products are vinylsilanetriol and methanol.
Therefore, the predicted half-lives for the registration and read-across substances at pH 2 are very rapid ( ≤ 0.1 hours) so all substances will be 90% hydrolysed to similar silicon-containing hydrolysis products after less than 20 minutes. Compared to the typical gastric emptying half-life for liquids in the order of 77 minutes in rats (RIVM, http://www.interspeciesinfo.com/Interspecies/Stomach), several hydrolysis half-lives would therefore have occurred and absorption in the intestine would almost exclusively relate to the final hydrolysis products. As a result, after oral administration, all three substances will hydrolyse rapidly in the stomach and systemic exposure will be to the similar hydrolysis products methylvinylsilanediol or vinylsilanetriol and methanol or ethanol. Therefore, read-across from triethoxy(vinyl)silane and trimethoxy(vinyl)silane to dimethoxy(methyl)vinylsilane for oral administration is considered to be valid.
Analogue approach justification
(a) Structural similarity
The registration and read-across substances are structurally similar and are members of an analogue group of methylvinyl silane substances. All contain a silicon atom to which is attached to a vinyl group which is identical for all three. The registered substance has two alkoxy groups bound to silicon, the read-across substances have three. For the registered substance the two alkoxy groups are methoxy, the read-across substance trimethoxy(vinyl)silane has three such groups, while for the other read-across substance triethoxy(vinyl)silane, the three alkoxy groups are ethoxy. All hydrolyse rapidly to produce the similar silicon-containing hydrolysis products, methylvinylsilanediol or vinylsilanetriol and methanol or ethanol.
(b) Similar physicochemical characteristics
The key physicochemical parameters are summarised below.
Table: Key physicochemical parameters
|
Target (registration substance) |
Source (read-across substance |
Source (read-across substance |
CAS number |
016753-62-1 |
000078-08-0 |
002768-02-7 |
EC number |
240-816-6 |
201-081-7 |
220-449-8 |
Chemical Name |
dimethoxy(methyl)vinylsilane |
triethoxy(vinyl)silane |
trimethoxy(vinyl)silane |
Molecular weight |
132.23 |
190.31 |
148.23 |
log Kow(parent) |
2.3 |
3 |
Not applicable |
log Kow(silicon-containing hydrolysis product) |
-0.1 |
-2.0 |
-2.0 |
Water solubility (parent) |
3000 mg/L |
930 mg/L |
3E+04 mg/L |
Water solubility (silicon-containing hydrolysis product) |
5E+05 mg/L |
1E+06 mg/L |
1E+06 mg/L |
Vapour pressure (parent) |
3000 Pa |
304 Pa |
1190 Pa |
Vapour pressure (silicon-containing hydrolysis product) |
2.1 Pa |
0.02 Pa |
0.02 Pa |
(c) Similar toxicokinetics
When oral exposure takes place it can be assumed, except for the most extreme of insoluble substances, that uptake through intestinal walls into the blood occurs. Uptake from intestines can be assumed to be possible for all substances that have appreciable solubility in water or lipid. Other mechanisms by which substances can be absorbed in the gastrointestinal tract include the passage of small water-soluble molecules (molecular weight up to around 200) through aqueous pores or carriage of such molecules across membranes with the bulk passage of water (Renwick, 1993). The hydrolysis products of the registered and read-across substances are all highly water soluble and have molecular weights less than 200 so systemic exposure is very likely following oral exposure. Therefore in view of the rapid hydrolysis following oral dosing, it is appropriate to read-across the available oral data for the read-across substances trimethoxy(vinyl)silane and triethoxy(vinyl)silane which produce similar silicon-containing hydrolysis products to address the potential for acute toxicity.
(d) Acute Toxicity
The alkyl alkoxy silanes, including vinyls, generally have oral and dermal LD50 values of greater than 2000 mg/kg bw and inhaled LC50 values greater than the maximum achievable test concentration (PFA, 2015t).
(e) Discussion of the acute toxicity of the non-silanol hydrolysis products
Both methanol and ethanol have a low order of acute toxicity and are considered not to contribute to any effects noted at the doses used in the studies with the read-across substances (OECD SIDS, 2004a and OECD 2004b).
OECD (2004): SIDS Initial Assessment Report for SIAM 19, Berlin, Germany, 18-20 October 2004, Methanol, CAS 67-56-1.
OECD (2004): SIDS Initial Assessment Report for SIAM 19, Berlin, Germany, 19-22 October 2004, Ethanol, CAS 64-17-5.
PFA (2015t): Analogue report: Mammalian toxicity of alkyl alkoxysilanes and silanols; PFA.404.002.002 (October 2015)
Renwick A. G. (1993) Data-derived safety factors for the evaluation of food additives and environmental contaminants. Fd. Addit. Contam. 10: 275-305.
Justification for selection of acute toxicity – oral endpoint
Studies were conducted according to or similar to an appropriate OECD test guideline. One was conducted in compliance with GLP. The GLP status of the second study is uncertain. The oral LD50 value for triethoxy(vinyl)silane is used for CSA as it is the lower value.
Justification for selection of acute toxicity – inhalation endpoint
Study was conducting according to an appropriate guideline and in compliance with GLP.
Justification for classification or non-classification
Based on the available for the substance itself and for related alkoxysilanes, dimethoxy(methyl)vinylsilane does not require classification for acute toxicity according to Regulation (EC) 1272/2008.
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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