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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
Sediment toxicity
Administrative data
Link to relevant study record(s)
- Endpoint:
- sediment toxicity: long-term
- Data waiving:
- other justification
- Justification for data waiving:
- other:
Reference
Description of key information
The substance hydrolyses rapidly and its silanol hydrolysis product has an estimated log Kow > 3 and an estimated log Koc of 5.6. Therefore, partitioning to the sediment compartment is expected. However, the substance has only a limited use pattern with intermediate uses and professional uses and therefore the exposure to sediment is expected to be minimal. Furthermore, in accordance with Annex XI, Section 3, exposure of aquatic organisms to the silanol hydrolysis product hexadecylsilanetriol was assessed as not significant (RCR < 1).
Key value for chemical safety assessment
Additional information
The registered substance trichloro(hexadecyl)silane (CAS No. 5894-60-0) hydrolyses very rapidly in contact with water (DT50 << 2 min at pH 7 and room temperature, EU Method C.7) to hexadecylsilanetriol and hydrochloric acid. REACH 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). TGD (EC, 2003) and REACH guidance R.16 (ECHA, 2016) also suggest that when the hydrolysis half-life is less than 12 h, the breakdown products, rather than the parent substance, should be evaluated for aquatic toxicity testing. Therefore, the hazard and risk assessment is based on the silanol hydrolysis product hexadecylsilanetriol. The second 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). Thus, hydrochloric acid is not considered to contribute to the overall aquatic toxicity of the registered substance. Therefore, hydrochloric acid can be disregarded in the environmental hazard assessment. In consequence, data for hydrochloric acid is not presented specifically for each environmental toxicity endpoint within this dossier.
The silanol hydrolysis product of the registered compound has high estimated log Kow and Koc values (5 and 5.6, respectively), therefore a partitioning into the sediment compartment is suggested. However, the parent compound has limited uses with only intermediate and professional uses. Hence, a release into the sediment compartment is expected to be minimal. Additionally, the silanol hydrolysis product is assessed as being inherently biodegradable based on read-across to structurally similar analogue substances and thus the substance does not persist in the environment. In accordance with Annex XI, Section 3, exposure of aquatic organisms to hexadecylsilanetriol is not significant. Furthermore, the hazard assessment based on acute aquatic toxicity data shows no toxicity toward aquatic organisms of all three trophic levels (all acute effect values, i.e. E(L)C50s were > 31.8 mg/L). Additionally, chronic toxicity tests on aquatic invertebrates and algae are available, which showed also no effects up to the highest concentrations tested (21-day NOEC ≥ 10 mg/L (daphnia), 72-h NOErC ≥ 31.8 mg/L (algae)). The substance is moderately soluble and thus, greater toxicity in long-term tests is unlikely. Even though no hazard was identified in acute aquatic studies, PNECs were derived for the purpose of risk characterization, using the threshold value of 10 mg/L (equivalent to 9 mg/L hexadecylsilanetriol) obtained in the chronic daphnia study in combination with standard safety factors as outlined in ECHA guidance R.10. As the substance hydrolyses rapidly, the environmental hazard assessment, PNEC derivation and risk characterization is based on the silanol hydrolysis product following a worst-case approach. The risk characterization for the silanol hydrolysis product indicated no risk to the aquatic environment including sediment (RCR < 1). For detailed information on the risk assessment, please see the attached documentation in chapter 13 (CSR).
References:
OECD SIDS, 2002. Hydrochloric acid - 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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