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EC number: 277-551-0 | CAS number: 73609-36-6
- 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
Ecotoxicological Summary
Administrative data
Hazard for aquatic organisms
Freshwater
- Hazard assessment conclusion:
- no hazard identified
Marine water
- Hazard assessment conclusion:
- no hazard identified
STP
- Hazard assessment conclusion:
- PNEC STP
- PNEC value:
- 0.92 mg/L
- Assessment factor:
- 100
- Extrapolation method:
- assessment factor
Sediment (freshwater)
- Hazard assessment conclusion:
- PNEC sediment (freshwater)
- PNEC value:
- 0.68 mg/kg sediment dw
- Extrapolation method:
- equilibrium partitioning method
Sediment (marine water)
- Hazard assessment conclusion:
- PNEC sediment (marine water)
- PNEC value:
- 0.068 mg/kg sediment dw
- Extrapolation method:
- equilibrium partitioning method
Hazard for air
Air
- Hazard assessment conclusion:
- no hazard identified
Hazard for terrestrial organisms
Soil
- Hazard assessment conclusion:
- PNEC soil
- PNEC value:
- 0.14 mg/kg soil dw
- Extrapolation method:
- equilibrium partitioning method
Hazard for predators
Secondary poisoning
- Hazard assessment conclusion:
- PNEC oral
- PNEC value:
- 3.33 mg/kg food
- Assessment factor:
- 300
Additional information
The hydrolysis half-life of [2-(perfluorohexyl)ethyl]dichloro(methyl)silane (CAS 73609-36-6) is <1 minute at pH 7, 20-25⁰C based on read-across data. The substance will hydrolyse in water under dilute conditions to [2-(perfluorohexyl)ethyl]methylsilanediol and hydrochloric acid. REACH guidance (ECHA 2016, R.16) states that “for substances where hydrolytic DT50 is less than 12 hours, environmental effects are likely to be attributed to the hydrolysis product rather than to the parent itself”. TGD and ECHA guidance (EC 2003, ECHA 2016) also suggest that when the hydrolysis half-life is less than 1 hour, the breakdown products, rather than the parent substance, should be evaluated for aquatic toxicity. Therefore, the environmental hazard assessment is based on the properties of the silanol hydrolysis product, in accordance with REACH guidance. As described in Section 4.8 of IUCLID, the silanol hydrolysis products may be susceptible to condensation reactions.
[2-(Perfluorohexyl)ethyl]methylsilanediol has very low water solubility (0.0048 mg/l), high log Kow (4.6) and low vapour pressure (0.38 Pa).
In order to reduce testing, read-across is proposed to fulfil up to REACH Annex VIII requirements for the registration substance from substances that have similar structure and physicochemical properties. Ecotoxicological studies are conducted in aquatic medium or in moist environments; therefore the hydrolysis rate of the substance is particularly important, because after hydrolysis occurs the resulting product has different structural features, physicochemical properties and behaviour.
The registration substance and the substance used as surrogate for read-across are part of a class of low-functionality compounds acting via a non-polar narcosis mechanism of toxicity. The group of organosilicon substances in this group contain alkyl, aryl, alkoxy or hydroxy groups attached to the silicon atom when present in aqueous solution. Secondary features may be present in the alkyl chain (e.g. halogen, nitrile, unsaturated bonds) that do not affect the toxicity of the substances (additional information is given in a supporting report (PFA, 2016y) attached in Section 13). The silanol hydrolysis products may be susceptible to condensation reactions, see Section 4.8.
The analogue approach for fulfilling the data requirement by read-across is discussed in the RAAF report for ecotoxicity attached in Section 13 of IUCLID, according to the Read-across Assessment Framework (RAAF).
References:
EC 2003:European Union Technical Guidance Document on Risk Assessment for New and Existing Substances, Part II, European Chemicals Bureau, 2003.
ECHA 2016: European Chemicals Agency. Guidance on information requirements and chemical safety assessment Chapter R.16: Environmental Exposure Estimation. Version: 3.0, February 2016.
Horvath, A.L. (1982) Halogenated Hydrocarbons. Solubility-Miscibility with Water, Marcel Dekker, New York, 1982.
OECD SIDS (2002) SIDS Initial Assessment Report for SIAM 15, Boston, USA, 22-25th October 2002, Hydrochloric acid, CAS 7647-01-0.
OECD (2004b): SIDS Initial Assessment Report for SIAM 19, Berlin, Germany, 19-22 October 2004, Ethanol, CAS 64-17-5.
PFA, 2016y, Peter Fisk Associates, Analogue Report - Ecotoxicity of substances with ‘low-functionality’ side chains attached to silicon, PFA. 404.003.004.R1
Conclusion on classification
The substance has reliable short-term E(L)C50 values of >3.1 mg/l (greater than the limit of solubility) in fish, >9 mg/l (greater than the limit of solubility in water) in invertebrates and >7.1 mg/l (greater than the limit of solubility in water) in algae, as well as a reliable NOEC of ≥7.1 mg/l (greater than the limit of solubility) in algae, based on read-across data from the structural analogue [2-(perfluorohexyl)ethyl]triethoxysilane (CAS 51851-37-7). The available aquatic toxicity data indicate that there are no effects on aquatic organisms at the limit of solubility of the substance in water.
The registration substance hydrolyses rapidly to [2-(perfluorohexyl)ethyl]methylsilanediol, which is not readily biodegradable, based on read-across data, and is poorly water soluble, which could mean it is likely to persist in the environment. The log Kow is >4 (4.6) and so the 'safety net' criteria for classification applies.
These data are consistent with the following classification under Regulation (EC) No 1272/2008 (as amended) (CLP):
Acute toxicity: Not classified.
Chronic toxicity: Category Chronic 4
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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