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EC number: 231-166-4 | CAS number: 7440-58-6
- 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
Endpoint summary
Administrative data
Description of key information
No data is available for skin irritation/corrosion or eye irritation on Hf substance ; read across with HfO2 and ZrO2 data is performed. Due to its inert property, the substance is neither a skin irritant, nor an eye irritant. These results are confirmed by different key studies.
Key value for chemical safety assessment
Skin irritation / corrosion
Link to relevant study records
- Endpoint:
- skin irritation: in vitro / ex vivo
- Type of information:
- migrated information: read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- key study
- Study period:
- 2011
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: GLP study conducted without any deviations to the guideline, but quoted with 2 because of the read across
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- EU Method B.46 (In Vitro Skin Irritation: Reconstructed Human Epidermis Model Test)
- Deviations:
- no
- GLP compliance:
- yes (incl. QA statement)
- Species:
- other: in vitro test using human skin model
- Details on test animals or test system and environmental conditions:
- not applicable
- Vehicle:
- water
- Amount / concentration applied:
- TEST MATERIAL
- Amount(s) applied: 10 mg (26.3 mg/cm²) of the crushed powder were applied to the epidermis surface
VEHICLE: 5µL distilled water were used as vehicle - Details on study design:
- The study was carried out with the Episkin SM tissues provided as a kit.
The tissues were exposed to the substance during 15 minutes and then post incubated 42h. The viability was determined by optical densimetry at 550nm to check the colouring potential of the substance (= reduction of MTT). - Irritation / corrosion parameter:
- other: other: MTT reduction showed by optical density
- Value:
- 98.4
- Remarks on result:
- other:
- Remarks:
- Basis: other: mean tissue viability. Reversibility: other: not applicable. (migrated information)
- Irritant / corrosive response data:
- The mean relative tissues viability is ≥ 50% and then substance showed no irritant effects.
- Interpretation of results:
- not irritating
- Remarks:
- Migrated information Criteria used for interpretation of results: other: UN GHS and EU CLP
- Executive summary:
The potential of the test item to induce skin irritation was tested by using the three dimensional human skin model Episkin-SM. HfO2 was applied with water topically to the tissue for 15 minutes followed by a 42h post incubation period and immediate determination of cytotoxic effects via MTT reduction assay.
Irritant potential was predicted from the relative mean tissue viabilities obtained compared to the negative control treated with PBS.
HfO2 showed no irritant effects as the mean relative tissue viability was ≥ 50% (98.4%).
The controls confirmed the validity of the study:
- the mean optical density of the six blank values was < 0.1
- the mean absolute OD of the three negative control tissues was ≥0.6 and ≤ 1.5
- the mean relative tissue viability of the positive control (SDS 5%) was ≤ 40% (6.7%)
- the maximum standard deviation of viability of replicate tissues of all dose groups was ≤ 18% (1.3 - 4.5%).
Reference
table of results:
|
Negative control : PBS |
Positive control : SDS 5% |
HfO2 |
||||||
Blank corrected mean OD at 550nm |
0.847 |
0.883 |
0.859 |
0.049 |
0.055 |
0.070 |
0.892 |
0.816 |
0.838 |
Blank corrected mean OD of the 3 replicates |
0.863 |
0.058 |
0.849 |
||||||
Standard deviation OD |
0.02 |
0.01 |
0.04 |
||||||
Relative tissue viabilities % |
98.1 |
102.4 |
99.5 |
5.7 |
6.3 |
8.1 |
103.4 |
94.6 |
97.1 |
Mean tissue viabilities % |
100 |
6.7 |
98.4 |
||||||
Standard deviation tissue viabilities % |
2.2 |
1.3 |
4.6 |
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed (not irritating)
Eye irritation
Link to relevant study records
- Endpoint:
- eye irritation: in vivo
- Type of information:
- migrated information: read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: see 'Remark'
- Remarks:
- Well documented, scientifically sound study with methods similar to OECD guidline 405 with the following deviations: Not GLP, no information on environmental conditions, individual eye endpoints (cornea, iris, conjunctiva) were not reported in the results.
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 405 (Acute Eye Irritation / Corrosion)
- Deviations:
- yes
- Remarks:
- Not GLP, no information on environmental conditions, individual eye endpoints (cornea, iris, conjunctiva) were not reported in the results.
- GLP compliance:
- no
- Species:
- rabbit
- Strain:
- New Zealand White
- Details on test animals or tissues and environmental conditions:
- TEST ANIMALS
- Source: Biotech Co., Ltd
- Age at study initiation: 4 months old
- Weight at study initiation: 3.22-3.59 kg
- Housing: no data
- Diet (e.g. ad libitum): no data
- Water (e.g. ad libitum): no data
- Acclimation period: no data
ENVIRONMENTAL CONDITIONS
- Temperature (°C): no data
- Humidity (%): no data
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): no data
IN-LIFE DATES: From: no data To: no data - Vehicle:
- unchanged (no vehicle)
- Controls:
- other: right eyes were kept as controls
- Amount / concentration applied:
- TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.1 g
- Concentration (if solution): not aplicable
VEHICLE
- Amount(s) applied (volume or weight with unit): not aplicable
- Concentration (if solution): not aplicable
- Lot/batch no. (if required): not aplicable
- Purity: not aplicable - Duration of treatment / exposure:
- single instillation
- Observation period (in vivo):
- 1, 24, 48, and 72 hours
- Number of animals or in vitro replicates:
- 3 animals (administered to the left eye of each animal)
- Details on study design:
- SCORING SYSTEM: according to Draize’s standard (1959); Cornea, iris and conjunctiva were observed, and acknowledged damages were recorded. After calculating the total scores of each observation of each animal (Individual ocular irritation index, IOI) and the average score of each observation of each group (Mean ocular irritation index, MOI), the evaluation was made according to the AFNOR (1982) evaluation criteria. The acute ocular irritation index (AOI) was defined as the maximum of the MOI.
Accident Value Test of Corneal Epithelium: After the accident value test of anterior ocular segment done 24 hours after the application, corneal epithelium were dyed with fluorescein, and the stainability was evaluated.
TOOL USED TO ASSESS SCORE: hand-slit lamp - Irritation parameter:
- other: MOI
- Basis:
- mean
- Time point:
- other: 48 hours
- Score:
- 2
- Max. score:
- 110
- Reversibility:
- fully reversible within: 72 hours
- Irritation parameter:
- other: AOI
- Basis:
- mean
- Time point:
- other: 24 hours
- Score:
- 6
- Max. score:
- 110
- Reversibility:
- fully reversible within: 72 hours
- Irritation parameter:
- other: Ocular reaction score
- Basis:
- mean
- Time point:
- other: 48 hours
- Score:
- 2
- Max. score:
- 110
- Reversibility:
- fully reversible within: 72 hours
- Irritation parameter:
- other: MOI
- Basis:
- mean
- Time point:
- other: 24 hours
- Score:
- 6
- Max. score:
- 110
- Reversibility:
- fully reversible
- Remarks:
- 72 hours
- Irritation parameter:
- other: MOI
- Basis:
- mean
- Time point:
- other: 72 hours
- Score:
- 0
- Max. score:
- 110
- Irritation parameter:
- other: MOI
- Basis:
- mean
- Time point:
- other: 1 hour
- Score:
- 4.7
- Max. score:
- 110
- Reversibility:
- fully reversible within: 72 hours
- Irritant / corrosive response data:
- The AOI was determined to be 6.0 at 24 hours and the MOI after 48 hours was 2.0, therefore, this test agent was determined to be slightly irritating based on the AFNOR (1982) criteria. No irritation was observed after 72 hours.
The Accident Value Test of Corneal Epithelium 24 hours after application was zero in all three animals. - Other effects:
- There were no abnormalities in the general condition or the weight changes to any of the 3 animals.
- Interpretation of results:
- not irritating
- Remarks:
- Migrated information Criteria used for interpretation of results: EU
- Conclusions:
- The test agent was determined to be slightly irritating based on the AFNOR criteria. It does however not need to be classified for eye irritation according to the rules in the DSD and CLP.
- Executive summary:
In this GLP study, performed according to the OECD 404 guideline,the test substance was determined to be slightly irritating based on the AFNOR criteria. Observed effects were fully reversible within 72 hours. It does however not need to be classified for eye irritation according to the rules in the DSD and CLP.
Reference
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed (not irritating)
Respiratory irritation
Endpoint conclusion
- Endpoint conclusion:
- no study available
Additional information
- skin irritation/corrosion
- eye irritation
According to the REACh recommendations for the DNEL derivation (Guidance on information requirements and chemical safety assessment Chapter R.8: characterisation of dose (concentration)-response for human health), a read across could be used for substances with similar behaviour and toxic effects in the organism.
HfO2 and ZrO2 were used in a read across approach, for which the justification was developped in the toxicological headchapter summary.
Four reliable studies are identified to assess the irritant potential of Hf. These studies are performed with Hf or with HfO2 and ZrO2 used for read across:
The first one showed the potential of HfO2 to induce skin irritation by using the three dimensional human skin model Episkin-SM, in a GLP study. HfO2 showed no irritant effects as the mean relative tissue viability was ≥ 50% (98.4%).
The second one, used wires containing 97 % Hf, as implant materials in Wistar rats. After 4 weeks of implantation, no inflammatory response was observed around the implants.
The two last ones, are GLP studies, performed according to the OECD 404 guideline, with New Zealand White rabbits exposed 4 hours to ZrO2 under an occlusive patch. No irritation, nor erythema, nor oedema were observed. The substance was hence determined not to be irritating to New Zealand White rabbit skin after 4 hours of exposure.
A reliable study was performed (Tosoh, 2000 – Klimisch 2) in New Zealand White rabbit. The test substance was ZrO2, used as read across, and was determined to be slightly irritating based on the AFNOR criteria. Observed effects were fully reversible within 72 hours.The slight irritation observed in the study performed with ZrO2, after 48 hours, is due to a mechanical action of the powder applied on the eyes.
Justification for classification or non-classification
Based on the available data, the substance was not classified under the CLP Regulation 1272/2008 nor the directive Classification and Labelling 67/548/EC.
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