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EC number: 227-575-2 | CAS number: 5894-60-0
- 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
Long-term toxicity to fish
Administrative data
Link to relevant study record(s)
- Endpoint:
- fish early-life stage toxicity
- Data waiving:
- exposure considerations
- Justification for data waiving:
- other:
Reference
Description of key information
A long-term toxicity study on fish is not necessary as
- exposure considerations in accordance with Annex XI, Section 3, indicate that exposure of aquatic organisms to trichloro(hexadecyl)silane is absent or not significant
and
- the substance has a low hazard potential based on the available toxicity data.
Key value for chemical safety assessment
Additional information
In accordance with Annex XI, Section 3, exposure of aquatic organisms to trichloro(hexadecyl)silane (CAS No. 5894-60-0) is absent or not significant.
The environmental hazard assessment, PNEC derivation and risk characterization is based on the silanol hydrolysis product, hexadecylsilanetriol, as the substance hydrolyses very rapidly under environmental conditions (DT50 << 2 min at pH 7 and room temperature). The other hydrolysis product, hydrochloric acid is well characterised in the public domain literature and effects on aquatic organisms arising from exposure to hydrochloric acid are thought to result from a reduction in the pH of the ambient environment (arising from an increase in the H+ concentration) to a level below their tolerable range. Aquatic ecosystems are characterized by their ambient conditions, including the pH, and resident organisms are adapted to these conditions. The pH of aquatic habitats can range from 6 in poorly-buffered ‘soft’ waters to 9 in well-buffered ‘hard’ waters. The tolerance of aquatic ecosystems to natural variations in pH is well understood and has been quantified and reported extensively in ecological publications and handbooks (e.g. OECD SIDS for CAS 7647-01-0, hydrochloric acid). It is not considered appropriate or useful to derive a single aquatic PNEC for hydrochloric acid because any effects will not be a consequence of true chemical toxicity and will be a function of, and dependent on, the buffering capacity of the environment. Generally the changes in pH of the receiving water should stay within the natural range of the pH, and for this reason, adverse effects on the aquatic environment are not expected due to anthropogenic or naturally occurring hydrochloric acid (OECD SIDS, 2002). Therefore, hydrochloric acid is not relevant for the assessment of aquatic toxicity.
No acute and chronic aquatic toxicity data is available for the registered compound trichloro(hexadecyl)silane (CAS No. 5894-60-0) or its silanol hydrolysis product. Therefore, good quality data was read-across from the structurally analogue substances trimethoxy(hexadecyl)silane (CAS No. 16415-12-6). The source substance hydrolyses slowly under environmental conditions (DT50 > 14 d at pH 7), but it forms the identical silanol hydrolysis product as the target compound and methanol as the second hydrolysis product instead of hydrochloric acid (target). The second hydrolysis product formed by the source substance, methanol, is also well characterised in the public domain literature and is not hazardous at the concentrations relevant to the studies (OECD SIDS, 2004). Thus, methanol is not considered contributory to the overall aquatic toxicity of the source substance and can be disregarded in the assessment. Additional information on the source substance CAS No. 16415-12-6 is given in a supporting read-across justification attached in IUCLID Section 13.
Short-term aquatic toxicity data is available for all three trophic levels (fish, algae, aquatic invertebrates) on the source compound. The hazard assessment showed no short-term aquatic hazard to all three trophic levels (all acute effect values > 31.8 mg/L). Additionally, no chronic effects were observed in aquatic invertebrates with a 21-d NOEC of ≥10 mg/L and algae with a 72-h NOEC of ≥ 31.8 mg/L. Consequently, no PNECs aqua (freshwater/marine water) were derived as no effects were observed on the read-across source substance. However, for the purpose of exposure-based adaptation as in the present endpoint, PNECs were derived in the Chemical Safety Report (CSR, Chapters 9 and 10) for the required risk characterization even though no hazard was identified in the available aquatic toxicity studies. The PNECs aqua (freshwater/marine water) were derived using a worst-case threshold value of 10 mg/L obtained in the chronic study on daphnia (equivalent to 9 mg/L when based on the silanol hydrolysis product hexadecylsilanetriol) in combination with the standard assessment factors of 50 and 500, respectively, as outlined in ECHA guidance R.10 (2008). The result was obtained under semi-static test conditions. In view of slow hydrolysis rate and exposure regime it is likely that the test organisms were exposed predominantly to the parent of the tested substance.
The silanol hydrolysis product hexadecylsilanetriol is moderately water-soluble (4.7 mg/L at 20 °C) and is expected to be inherently biodegradable based on a read-across to the source substance chloro(dimethyl)octadecylsilane, which shares a structurally similar silanol hydrolysis product compared to the silanol hydrolysis product of the registered substance. Significant deviations from this overall ecotoxicity profile are not expected and greater long-term toxicity in an additional test with fish is considered unlikely.
The risk characterization for the silanol hydrolysis product of the registered compound indicated no risk to the aquatic environment (RCR < 1).
For detailed information on the risk assessment please refer to the attached documentation in Section 13.
References:
OECD, 2002. Hydrogen Chloride - SIDS Initial Assessment Report for SIAM 15, Boston, USA: UNEP Publications.
OECD SIDS, 2004. Methanol - SIDS Initial Assessment Report For SIAM 19, Berlin, Germany: UNEP Publications.
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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