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EC number: 213-773-6 | CAS number: 1009-93-4
- 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
Biodegradation in water: screening tests
Administrative data
Link to relevant study record(s)
Description of key information
Biodegradation in water: screening tests: 15.3% in 28 days (O2 consumption; taking into account potential for nitrification). Not readily biodegradable, read-across from a structurally-related substance. No significant biodegradation of the silanol hydrolysis product is expected.
Key value for chemical safety assessment
- Biodegradation in water:
- under test conditions no biodegradation observed
Additional information
There are no reliable ready biodegradation data available for 2,2,4,4,6,6-hexamethylcyclotrisilazane (CAS 1009-93-4), therefore good quality data for the structurally-related substance, 1,1,1,3,3,3-hexamethyldisilazane (999-97-3), have been read across. Both substances have similar silanol hydrolysis products, dimethylsilanediol and trimethylsilanol respectively. The other hydrolysis product is ammonia/ammonium ions in both cases.
Ammonia/ammonium ions are inorganic and biodegradation is not relevant.
2,2,4,4,6,6-hexamethylcyclotrisilazane (CAS 1009-93-4) and 1,1,1,3,3,3-hexamethyldisilazane (999-97-3) are within an analogue group of substances within which, in general, there is no evidence of any significant biodegradation once hydrolysis and subsequent biodegradation of alkoxy/acetoxy groups has been taken into account.
This analogue group for the ready biodegradability endpoint consists of a number of sub-classes of substances (based on structure/functionality) with different main codes (used to represent the different sub-classes). However, read-across is carried out between substances with the same main code in most cases.
The table below presents ready biodegradation data for substances within the sub-class II-3-1 of substances containing Si-N bonds. 2,2,4,4,6,6-hexamethylcyclotrisilazane (CAS 1009-93-4) and 1,1,1,3,3,3-hexamethyldisilazane (999-97-3) are members of this main code.
It is therefore considered valid to read-across the results for 1,1,1,3,3,3-hexamethyldisilazane (999-97-3) to fill the data gap for the registered substance. Additional information is given in a supporting report (PFA, 2013f) attached in Section 13.
Table: Ready biodegradation data available for substances within the relevant main code (II-3-1) of chemicals
CAS No. |
Name |
Main code |
Readily biodegradable? Yes/no |
Result: Biodegradation after 28 days (%) |
Guideline |
PFA Klimisch code |
Corrected % biodegradation once alkoxy/acetoxy biodegradation is accounted for[1] |
7691-02-3 |
N-(dimethylvinylsilyl)-1,1-dimethyl-1-vinylsilylamine |
II-3-1 |
No |
0% |
"Biodegradation study of chemical substances by microorganisms and the like"[2] |
1 |
0 |
999-97-3 |
1,1,1,3,3,3-hexamethyldisilazane |
II-3-1 |
No |
15.30% |
EC C4-E |
1 |
15 |
388606-32-4 |
1-Propanamine, 3-[(2,2-dimethyl-1-aza-2-silacyclopent-1-yl)dimethylsilyl]- |
II-3-1 |
No |
1% |
OECD 301F |
1 |
1 |
[1]The negative values in this column are where the biodegradation rate observed in the test is less than that expected assuming only alkoxy/acetoxy parts biodegrade. This could be due to low solubility of parent substance or low rates of hydrolysis. These values should in effect be considered as zero.
[2]Stipulated in "Testing Method for New Chemical Substances etc." (Kanhogyo No.5, Yakuhatsu 615, 49Kikyoku No.392, July 13, 1974 )
In the study with 1,1,1,3,3,3-hexamethyldisilazane (CAS 999-97-3), 15.3% biodegradation was observed in 28 days. 1,1,1,3,3,3-hexamethyldisilazane (CAS 999-97-3) hydrolyses within the timescale of the ready biodegradation study to trimethylsilanol and ammonia/ammonium ions. The biodegradation observed in the study is attributable to the biodegradation of the silanol hydrolysis product. This is consistent with the expectation that significant biodegradation is not expected for the silanol hydrolysis product. The study was conducted according to EC method C4-E and is considered reliable. This is selected as the key study. The study is considered to be reliability 1 (reliable without restrictions); the read across of the result is considered to be reliability 2 (reliable with restrictions).
References:
PFA, 2013f, Peter Fisk Associates, Biodegradation Main Analogue Group report, PFA.300.005.007
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