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EC number: 215-150-4 | CAS number: 1306-38-3
- 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
Skin sensitisation
Administrative data
- Endpoint:
- skin sensitisation: in vivo (non-LLNA)
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- November 1982 - February 1983
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
Cross-referenceopen allclose all
- Reason / purpose for cross-reference:
- reference to same study
Reference
- Endpoint:
- skin irritation: in vivo
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- November 1982 - February 1983
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 404 (Acute Dermal Irritation / Corrosion)
- Deviations:
- no
- GLP compliance:
- no
- Remarks:
- The study was performed before the implementation of GLP.
- Species:
- rabbit
- Strain:
- New Zealand White
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Roucher, Couhé France - EGAV, Passais-la-Conception France - Elevage Scientifique des Dombes, Châtillon-sur-Chalaronne France - Gwen Meur, Trégonneau France
- Age at study initiation: not specified
- Weight at study initiation: 2.5 kg +/- 200 g
- Housing: individual polystyrene cages (54 x 36 x 31.5 cm)
- Diet: 150 g pelleted diet/animal/day
- Water: ad libitum
- Acclimation period: at least 8 days
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 +/- 3
- Humidity (%): 50 +/- 20
- Air changes (per hr): 12
- Photoperiod (hrs dark / hrs light): 12 / 12 (7.30 am - 7.30 pm)
IN-LIFE DATES: 23 November 1982 (application) - Type of coverage:
- semiocclusive
- Preparation of test site:
- shaved
- Vehicle:
- other: moistening with 0.1 mL water
- Controls:
- not required
- Amount / concentration applied:
- TEST MATERIAL
- Amount applied: 0.5 g - Duration of treatment / exposure:
- 4 hours
- Observation period:
- 14 days
- Number of animals:
- 3 males
- Details on study design:
- TEST SITE
- Area of exposure: approximately 6 cm² skin surface
- Type of wrap: semiocclusive dressing
REMOVAL OF TEST SUBSTANCE
- Washing: yes
- Time after start of exposure: 4 hours
SCORING SYSTEM:
- Erythema and Eschar Formation:
No erythema -> 0
Very slight erythema (barely perceptible) ->1
Well defined erythema -> 2
Moderate to severe erythema -> 3
Severe erythema (beef redness) to eschar formation preventing grading of erythema -> 4
- Oedema Formation:
No oedema -> 0
Very slight oedema (barely perceptible) -> 1
Slight oedema (edges of area well defined by definite raising) -> 2
Moderate oedema (raised approximately 1 mm) -> 3
Severe oedema (raised more than 1 mm and extending beyond area of exposure) -> 4
- Primary Dermal Irritation Index = (Sum of individual Erythema scores + Sum of individual Edema scores) / 12 - Irritation parameter:
- primary dermal irritation index (PDII)
- Basis:
- mean
- Time point:
- other: 1, 24, 48, 72 hours
- Score:
- 0
- Max. score:
- 8
- Reversibility:
- other: not applicable
- Irritation parameter:
- erythema score
- Basis:
- mean
- Time point:
- 24/48/72 h
- Score:
- 0
- Max. score:
- 4
- Reversibility:
- other: not applicable
- Remarks on result:
- no indication of irritation
- Irritation parameter:
- edema score
- Basis:
- mean
- Time point:
- 24/48/72 h
- Score:
- 0
- Max. score:
- 4
- Reversibility:
- other: not applicable
- Remarks on result:
- no indication of irritation
- Interpretation of results:
- GHS criteria not met
- Conclusions:
- Cerium Oxide is not considered to be a skin irritant.
- Executive summary:
In a primary dermal irritation study (Institut Français de Toxicologie report No. 302314), 3 male New Zealand White rabbits were dermally exposed to 0.5 g of Cerium Oxide moistened with 0.1 mL water applied on a ~6 cm² skin area maintained under semi-occlusive dressing for 4 hours. Animals then were observed for up to 72 hours. Irritation was scored 1, 24, 48 and 72 h after removal of the dressing by calculating dermal irritation scores, based on the grading of cutaneous erythema and oedema.
No signs of cutaneous erythema or oedema were observed. The dermal irritation scores were equal to 0.
The test substance was therefore considered as non-irritant to the skin. No classification for skin irritation is warranted based on the absence of cutaneous reactions following a 4-hour exposure, according to UN/EU GHS criteria.
This study is classified as acceptable. It satisfies the OECD 404 guideline requirements for acute dermal irritation or corrosion.
Summary table of individual irritation scores
Rabbit number |
445 |
446 |
447 |
Total |
Mean |
Erythema score |
|
|
|
|
|
Time points (h) 1 24 48 72 |
0 0 0 0 |
0 0 0 0 |
0 0 0 0 |
0 0 0 0 |
0 0 0 0 |
Oedema score |
|
|
|
|
|
Time points (h) 1 24 48 72 |
0 0 0 0 |
0 0 0 0 |
0 0 0 0 |
0 0 0 0 |
0 0 0 0 |
- Reason / purpose for cross-reference:
- reference to same study
Reference
- Endpoint:
- eye irritation: in vivo
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- November 1982
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 405 (Acute Eye Irritation / Corrosion)
- Deviations:
- no
- GLP compliance:
- no
- Remarks:
- The study was performed before the implementation of GLP.
- Species:
- rabbit
- Strain:
- New Zealand White
- Details on test animals or tissues and environmental conditions:
- TEST ANIMALS
- Source: Roucher, Couhé France - EGAV, Passais-la-Conception France - Elevage Scientifique des Dombes, Châtillon-sur-Chalaronne France - Gwen Meur, Trégonneau France
- Age at study initiation: not specified
- Weight at study initiation: 2.5 kg ± 200 g
- Housing: individual polystyrene cages (54 x 36 x 31.5 cm)
- Diet: 150 g pelleted diet/animal/day
- Water: ad libitum
- Acclimation period: at least 8 days
ENVIRONMENTAL CONDITIONS
- Temperature: 20 ± 3°C
- Humidity: 50 ± 20%
- Air changes: 12 per hr
- Photoperiod: 12 hrs dark / 12 hrs light (7.30 am - 7.30 pm)
IN-LIFE DATES: 25 November 1982 (instillation) - Vehicle:
- unchanged (no vehicle)
- Controls:
- no
- Amount / concentration applied:
- TEST MATERIAL
- Amount applied: 0.1 g - Duration of treatment / exposure:
- Single conjunctival instillation
- Observation period (in vivo):
- 7 days
- Number of animals or in vitro replicates:
- 3 males
- Details on study design:
- REMOVAL OF TEST SUBSTANCE
- No washing
SCORING SYSTEM:
- Conjunctivae
* Chemosis: Swelling (refers to lids and/or nictating membranes)
Normal -> 0
Some swelling above normal -> 1
Obvious swelling, with partial eversion of lids -> 2
Swelling, with lids about half closed -> 3
Swelling, with lids more than half closed -> 4
(VALUE A)
* Discharge
No discharge -> 0
Slight discharge -> 1
Discharge with humidification of lids and hair around -> 2
Discharge with humidification of lids and large area around -> 3
(VALUE B)
* Redness (refers to palpebral and bulbar conjunctivae; excluding cornea and iris)
Normal -> 0
Some blood vessels hyperaemic (injected) -> 1
Diffuse, crimson colour; individual vessels not easily discernible -> 2
Diffuse beefy red -> 3
(VALUE C)
- Iris
Normal -> 0
Markedly deepened rugae, congestion, swelling, moderate circumcorneal hyperaemia;
or injection; iris reactive to light (a sluggish reaction is considered to be an effect -> 1
Hemorrhage, gross destruction, or no reaction to light -> 2
(VALUE D)
- Cornea
* Opacity: degree of density (readings from most dense area)
No ulceration or opacity -> 0
Scattered or diffuse areas of opacity (other than slight dulling of normal lustre);
details of iris clearly visible -> 1
Easily discernible translucent area; details of iris slightly obscured -> 2
Nacrous area; no details of iris visible; size of pupil barely discernible -> 3
Opaque cornea; iris not discernible through the opacity -> 4
(VALUE E)
* Surface of opacity:
Less than 1/4 -> 1
Between 1/4 and 1/2 -> 2
Between 1/2 and 3/4 -> 3
Between 3/4 and whole surface -> 4
(VALUE F)
=> Conjunctiva score = 2 x (A + B + C)
=> Iris score = 5 x D
=> Cornea score = 5 x E x F
=> Individual total score (per time-point) = Conjunctiva + Iris + Cornea scores (maximum 110)
=> Maximum Mean Total Score (at a given time-point)
TOOLS USED TO ASSESS SCORE: Heine's ophthalmoscope ± slit lamp - Irritation parameter:
- cornea opacity score
- Basis:
- mean
- Time point:
- 24/48/72 h
- Score:
- 0
- Max. score:
- 4
- Reversibility:
- other: not applicable
- Remarks on result:
- no indication of irritation
- Irritation parameter:
- iris score
- Basis:
- mean
- Time point:
- 24/48/72 h
- Score:
- 0
- Max. score:
- 2
- Reversibility:
- other: not applicable
- Remarks on result:
- no indication of irritation
- Irritation parameter:
- conjunctivae score
- Basis:
- mean
- Time point:
- 24/48/72 h
- Score:
- 0
- Max. score:
- 3
- Reversibility:
- other: not applicable
- Remarks on result:
- no indication of irritation
- Irritation parameter:
- chemosis score
- Basis:
- mean
- Time point:
- 24/48/72 h
- Score:
- 1
- Max. score:
- 4
- Reversibility:
- fully reversible within: Day 3
- Remarks on result:
- no indication of irritation
- Irritation parameter:
- overall irritation score
- Basis:
- mean
- Time point:
- other: 1 hour
- Score:
- 9.33
- Max. score:
- 110
- Reversibility:
- fully reversible within: 3 days from instillation
- Irritation parameter:
- overall irritation score
- Basis:
- mean
- Time point:
- 24 h
- Score:
- 1.33
- Max. score:
- 110
- Reversibility:
- fully reversible within: 3 days from instillation
- Irritation parameter:
- overall irritation score
- Basis:
- mean
- Time point:
- 48 h
- Score:
- 0.67
- Max. score:
- 110
- Reversibility:
- fully reversible within: 3 days from instillation
- Irritant / corrosive response data:
- See table below for details
- Interpretation of results:
- GHS criteria not met
- Remarks:
- slightly irritating
- Conclusions:
- Cerium Oxide is not classified as an eye irritant.
- Executive summary:
In a primary eye irritation study (Institut Français de Toxicologie report No. 302314), 0.1 g of Cerium Oxide were instilled into the conjunctival sac of the right eye of 3 male New Zealand White rabbits. Exposed eyes were not washed. Animals then were observed for 7 days. Irritation was scored 1 hours after instillation and on days 1, 2, 3, 4 and 7 by calculating ocular irritation scores, based on the grading of conjunctiva, iris and cornea scores.
Slight to moderate conjunctival chemosis was observed in all 3 rabbits within 48 hours after instillation, together with slight conjunctival discharge in all animals and conjunctival enanthema and iris congestion in 2 animals, at 1 hour after instillation. All the irritation signs had reversed by day 3. Mean ocular irritation scores were 9.33, 1.33 and 0.67 at 1 h after instillation and on days 1 and 2, respectively.
The test substance was therefore not classified as irritant to the eye, according to UN/EU GHS criteria.
This study is classified as acceptable. It satisfies the OECD 405 guideline requirements for acute eye irritation or corrosion.
Summary of the observed ocular irritation scores (3 rabbits)
Time after instillation |
1 h |
|
|
1 d |
|
|
2 d |
|
|
Rabbit number |
448 |
449 |
450 |
448 |
449 |
450 |
448 |
449 |
450 |
Conjunctivae Chemosis Discharge Redness |
2 1 1 |
1 1 1 |
1 1 0 |
1 0 0 |
0 0 0 |
1 0 0 |
1 0 0 |
0 0 0 |
0 0 0 |
Iris |
1 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Cornea Opacity Surface |
0 0 |
0 0 |
0 0 |
0 0 |
0 0 |
0 0 |
0 0 |
0 0 |
0 0 |
Individual score |
13 |
11 |
4 |
2 |
0 |
2 |
2 |
0 |
0 |
Mean (3 animals) |
- |
- |
9.33 |
- |
- |
1.33 |
- |
- |
0.67 |
|
|
|
|
|
|
|
|
|
|
Time after instillation |
3 d |
|
|
4d |
|
|
7 d |
|
|
Rabbit number |
448 |
449 |
450 |
448 |
449 |
450 |
448 |
449 |
450 |
Conjunctivae Chemosis Discharge Redness |
0 0 0 |
0 0 0 |
0 0 0 |
0 0 0 |
0 0 0 |
0 0 0 |
0 0 0 |
0 0 0 |
0 0 0 |
Iris |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Cornea Opacity Surface |
0 0 |
0 0 |
0 0 |
0 0 |
0 0 |
0 0 |
0 0 |
0 0 |
0 0 |
Individual score |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
Mean (3 animals) |
- |
- |
0 |
- |
- |
0 |
- |
- |
0 |
Data source
Reference
- Reference Type:
- study report
- Title:
- Unnamed
- Year:
- 1 983
- Report date:
- 1983
Materials and methods
Test guideline
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 406 (Skin Sensitisation)
- Deviations:
- no
- GLP compliance:
- no
- Remarks:
- The study was performed before the implementation of GLP.
- Type of study:
- guinea pig maximisation test
- Justification for non-LLNA method:
- The Guinea Pig Maximisation Test (OECD TG 406) was selected based on the fact that insoluble inorganic forms such cerium dioxide are often not able to penetrate the skin. Furthermore, OECD Guideline 429 (LLNA) test was not validated in 1983.
Test material
- Reference substance name:
- Cerium dioxide
- EC Number:
- 215-150-4
- EC Name:
- Cerium dioxide
- Cas Number:
- 1306-38-3
- Molecular formula:
- CeO2
- IUPAC Name:
- cerium dioxide
- Test material form:
- solid: bulk
Constituent 1
In vivo test system
Test animals
- Species:
- guinea pig
- Strain:
- Dunkin-Hartley
- Sex:
- male/female
- Details on test animals and environmental conditions:
- TEST ANIMALS
- Source: Iffa-Crédo, France or Shamrock Farms, UK or Gwen Meur, France
- Age at study initiation: 5 to 7 weeks old
- Weight at study initiation: 300 to 500 g
- Housing: by group of 5 of the same sex, in polystyrene cages (54 x 36 x 31.5 cm)
- Diet: 50 g of pelleted diet/animal/day
- Water: ad libitum
- Acclimation period: 8 days
ENVIRONMENTAL CONDITIONS
- Temperature: 20 ± 3°C
- Humidity: 50 ± 20%
- Air changes: 12 per hr
- Photoperiod: 12 hrs dark / 12 hrs light (7.30 am - 7.30 pm)
IN-LIFE DATES: From November 1982 To December 1982
Study design: in vivo (non-LLNA)
Inductionopen allclose all
- Route:
- intradermal
- Vehicle:
- water
- Concentration / amount:
- - Preliminary assay: 10%, 25% and 50% (w/w)
- Main assay: 50% (w/w) in treated group and vehicle only for control group - Day(s)/duration:
- 1 day
- Adequacy of induction:
- other: maximal non-irritating concentrations
- Route:
- epicutaneous, occlusive
- Vehicle:
- water
- Concentration / amount:
- - Preliminary assay: 0.5 g as such (100%) and 50% (w/w)
- Main assay: 0.5 g as such (100%) in treated group and vehicle only for control group - Day(s)/duration:
- 48 h
- Adequacy of induction:
- non-irritant substance, but skin pre-treated with 10% SDS
Challenge
- No.:
- #1
- Route:
- epicutaneous, occlusive
- Vehicle:
- water
- Concentration / amount:
- - Preliminary assay: 0.5 g as such (100%) and 50% (w/w) in water
- Main assay: 0.5 g as such (100%) in treated (left flank) group and vehicle only for control group (right flank) - Day(s)/duration:
- 24 hours
- Adequacy of challenge:
- other: maximal non-irritating concentrations
- No. of animals per dose:
- - Preliminary assay: 6 per sex
- Main assay: 10 treated + 5 controls per sex - Details on study design:
- RANGE FINDING TESTS:
6 animals per sex were used to determine maximal non irritating concentrations by intradermal route or topical occlusive patch application for 24 or 48 hours.
MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 3 series of 2 intradermal injections (adjuvant, test substance and test substance in adjuvant) + one 48-hour topical application (test substance)
- Exposure period: 1 days for intradermal injections, 2 days for topical applications
- Test groups: Freund's adjuvant + Test substance in vehicle
- Control group: Freund's adjuvant + Vehicle alone
- Site: Interscapular area
- Frequency of applications: single topical application
- Duration: 10 days total
- Concentrations: 50% (w/w) in water for intradermal injections, 0.5 g as such (100%) for dermal applications
- Before dermal application, 0.5 mL of a Sodium Lauryl Sulfate solution (10% in vaseline) were applied to the application site to create local irritation
B. CHALLENGE EXPOSURE
- No. of exposures: one 24-hour topical application (test substance)
- Day(s) of challenge: day 21
- Exposure period: 1 day
- Test groups: Vehicle alone + Test substance in vehicle
- Control group: Vehicle alone + Test substance in vehicle
- Site: Left flank (test substance) + right flank (vehicle)
- Concentrations: 0.5 g as such (100%)
- Evaluation (hr after challenge): 1, 6, 24 and 48
OTHER:
Macroscopic dermal reactions (erythema and edema) were graded using the following scale:
No reaction -> 0
Slight erythema -> 1
Moderate erythema -> 2
Sever erythema -> 3 - Challenge controls:
- Vehicle controls on the treated animals (left flanks) + Control group (no contact with test substance during induction phase)
- Positive control substance(s):
- not specified
- Remarks:
- No positive control was reported in this study.
Results and discussion
- Positive control results:
- No positive control has been reported in this study performed in 1983.
In vivo (non-LLNA)
Resultsopen allclose all
- Reading:
- 1st reading
- Hours after challenge:
- 1
- Group:
- negative control
- Dose level:
- 0 (vehicle alone, right flank)
- No. with + reactions:
- 0
- Total no. in group:
- 10
- Clinical observations:
- None
- Reading:
- 1st reading
- Hours after challenge:
- 1
- Group:
- negative control
- Dose level:
- 0.5 g (left flank)
- No. with + reactions:
- 4
- Total no. in group:
- 10
- Clinical observations:
- Slight skin erythema (Grade 1) observed in 4 animals
- Reading:
- 1st reading
- Hours after challenge:
- 6
- Group:
- negative control
- Dose level:
- 0 (vehicle alone, right flank)
- No. with + reactions:
- 0
- Total no. in group:
- 10
- Clinical observations:
- None
- Reading:
- 1st reading
- Hours after challenge:
- 6
- Group:
- negative control
- Dose level:
- 0.5 g (left flank)
- No. with + reactions:
- 5
- Total no. in group:
- 10
- Clinical observations:
- Slight skin erythema (Grade 1) was observed in 5 animals
- Reading:
- 1st reading
- Hours after challenge:
- 24
- Group:
- negative control
- Dose level:
- 0 (vehicle alone, right flank)
- No. with + reactions:
- 0
- Total no. in group:
- 10
- Clinical observations:
- None
- Reading:
- 1st reading
- Hours after challenge:
- 24
- Group:
- negative control
- Dose level:
- 0.5 g (left flank)
- No. with + reactions:
- 5
- Total no. in group:
- 10
- Clinical observations:
- Slight skin erythema (Grade 1) was observed in 5 animals
- Reading:
- 1st reading
- Hours after challenge:
- 48
- Group:
- negative control
- Dose level:
- 0 (vehicle alone, right flank)
- No. with + reactions:
- 0
- Total no. in group:
- 10
- Clinical observations:
- None
- Reading:
- 1st reading
- Hours after challenge:
- 48
- Group:
- negative control
- Dose level:
- 0.5 g (left flank)
- No. with + reactions:
- 0
- Total no. in group:
- 10
- Clinical observations:
- None
- Reading:
- 1st reading
- Hours after challenge:
- 1
- Group:
- test chemical
- Dose level:
- 0 (vehicle alone, right flank)
- No. with + reactions:
- 0
- Total no. in group:
- 20
- Clinical observations:
- None
- Reading:
- 1st reading
- Hours after challenge:
- 1
- Group:
- test chemical
- Dose level:
- 0.5 g (left flank)
- No. with + reactions:
- 10
- Total no. in group:
- 20
- Clinical observations:
- Slight to moderate (Grade 1 or 2) skin erythema in 10 animals.
- Remarks on result:
- no indication of skin sensitisation
- Remarks:
- Based on histological analysis.
- Reading:
- 1st reading
- Hours after challenge:
- 6
- Group:
- test chemical
- Dose level:
- 0 (vehicle alone, right flank)
- No. with + reactions:
- 0
- Total no. in group:
- 20
- Clinical observations:
- None
- Reading:
- 1st reading
- Hours after challenge:
- 6
- Group:
- test chemical
- Dose level:
- 0.5 g (left flank)
- No. with + reactions:
- 13
- Total no. in group:
- 20
- Clinical observations:
- Slight to moderate (Score 1 to 2) skin erythema in 13 animals
- Remarks on result:
- no indication of skin sensitisation
- Remarks:
- Bases on histological analysis.
- Reading:
- 1st reading
- Hours after challenge:
- 24
- Group:
- test chemical
- Dose level:
- 0 (vehicle alone, right flank)
- No. with + reactions:
- 0
- Total no. in group:
- 20
- Clinical observations:
- None
- Reading:
- 1st reading
- Hours after challenge:
- 24
- Group:
- test chemical
- Dose level:
- 0.5 g (left flank)
- No. with + reactions:
- 8
- Total no. in group:
- 20
- Clinical observations:
- Slight skin erythema (Grade 1) in 8 animals
- Remarks on result:
- no indication of skin sensitisation
- Remarks:
- Based on histological analysis.
- Reading:
- 1st reading
- Hours after challenge:
- 48
- Group:
- test chemical
- Dose level:
- 0 (vehicle alone, right flank)
- No. with + reactions:
- 0
- Total no. in group:
- 20
- Clinical observations:
- None
- Reading:
- 1st reading
- Hours after challenge:
- 48
- Group:
- test chemical
- Dose level:
- 0.5 g (left flank)
- No. with + reactions:
- 3
- Total no. in group:
- 20
- Clinical observations:
- Slight skin erythema (Grade 1) in 3 animals
- Remarks on result:
- no indication of skin sensitisation
- Remarks:
- Based on histological analysis.
- Group:
- positive control
- Remarks on result:
- not measured/tested
- Remarks:
- No positive control were reported in this study.
Any other information on results incl. tables
Slight erythema (grade 1) on the treated flank (0.5 g as such) was noted among control animals between 1 hour and 24 hours following challenge, with incidences varying between 4/10 and 5/10 control animals. No sign of irritation was observed on the control flank (vehicle only) of the control animals.
Slight to moderate erythema (grade 1 or 2) on the treated flank (0.5 g as such) was noted among treated animals, with incidences of 10/20, 13/20, 8/20 and 3/20 animals at 1, 6, 24 and 48 hours following challenge, respectively.
No sign of irritation was observed on the control flank (vehicle only) of the treated animals.
None of these animals were considered to show positive skin sensitization reactions, using confirmation by histopathological examination.
Applicant's summary and conclusion
- Interpretation of results:
- GHS criteria not met
- Conclusions:
- No signs of delayed hypersensitivity in this Guinea Pig Maximisation Test using concentrations of 50% (w/w) in water (intradermal) or 0.5 g as such (epicutaneous).
- Executive summary:
In a dermal sensitization study using the Guinea Pig Maximisation Test method (Magnusson & Kligman), Cerium Oxide was administered to 5 to 7-week old Dunkin-Hartley Guinea pigs (6/sex used in preliminary assay, 5 controls and 10 treated/sex). Induction phase consisted of intradermal injections of 0.1 mL of a 50% (w/w) suspension of Cerium Oxide in water, a suspension of Cerium Oxide in a 50% (v/v) mixture of complete Freund's adjuvant and saline, or Freund's adjuvant alone (vehicle alone and adjuvant in controls), followed by dermal application of 0.5 g (100%) of Cerium Oxide on a skin surface of ~8cm² previously irritated by Sodium Lauryl Sulfate, and kept under occlusive dressing for 48 hours. Following an 11-day resting period, the challenge phase consisted of a dermal application of 0.5 g of Cerium Oxide on a skin surface of ~4cm² kept under occlusive dressing for 24 hours, and application of the vehicle alone (same for controls). Skin reactions (erythema and edema) indicative of potential sensitization were monitored 1, 6, 24 and 48 h after occlusive dressing removal.
In the preliminary assay, slight irritation was observed following intradermal injection of 50% (w/w) suspension in water (3/4 animals) or 25% (w/w) suspension in water (1/4 animals). The concentration of 50% (w/w) in water was therefore selected for the main assay. The maximal non-irritating concentration for induction and challenge phases was selected at 100% (0.5 g of the test substance as such). In the main assay, minimal to slight erythema was noted only on the treated flank among test animals, mostly within 24 h after challenge application. None of the test animals were considered to be positive for sensitization using histopathological examination for confirmation.
The test substance was therefore considered as non-sensitizing after skin contact in guinea pig. No classification for skin sensitization is warranted based on the absence of positive reactions in the Guinea Pig Maximisation Test, according to the UN/EU GHS criteria.
This study is classified as acceptable. It satisfies the OECD 406 guideline requirements for skin sensitization.
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