Registration Dossier

Toxicological information

Skin sensitisation

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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:
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:
reference to same study
Reason / purpose:
reference to same study
Qualifier:
according to
Guideline:
OECD Guideline 404 (Acute Dermal Irritation / Corrosion)
Deviations:
no
GLP compliance:
no
Species:
rabbit
Strain:
New Zealand White
Details on test animals 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

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

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 the criteria of Annex VI Directive 67/548/EEC or UN/EU GHS.

 

This study is classified as acceptable. It satisfies the OECD 404 guideline requirements for acute dermal irritation or corrosion.

Reason / purpose:
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
Qualifier:
according to
Guideline:
OECD Guideline 405 (Acute Eye Irritation / Corrosion)
Deviations:
no
GLP compliance:
no
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:
reading stopped at 48h
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:
reading stopped at 48h
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:
reading stopped at 48h
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: 24 hours
Remarks:
reading stopped at 48h
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

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

 

0

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

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 the criteria of Annex VI Directive 67/548/EEC.

 

This study is classified as acceptable. It satisfies the OECD 405 guideline requirements for acute eye irritation or corrosion.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1983
Report Date:
1983

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
no
GLP compliance:
no
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
Name:
Unnamed
Type:
Constituent

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:
other: maximal non-irritating concentrations; skin pre-treated with 10% SLS
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:
1 day
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 same animals (left flanks) + Control group (no contact with test substance during induction phase)
Positive control substance(s):
no

Results and discussion

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
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 1.0. Group: negative control. Dose level: 0 (vehicle alone, right flank). No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: None.
Reading:
1st reading
Hours after challenge:
1
Group:
negative control
Dose level:
0.5 g (left flank)
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
Slight skin erythema in 4 animals
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 1.0. Group: negative control. Dose level: 0.5 g (left flank). No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: Slight skin erythema 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
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 6.0. Group: negative control. Dose level: 0 (vehicle alone, right flank). No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: None.
Reading:
1st reading
Hours after challenge:
6
Group:
negative control
Dose level:
0.5 g (left flank)
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
Slight skin erythema in 5 animals
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 6.0. Group: negative control. Dose level: 0.5 g (left flank). No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: Slight skin erythema 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
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 0 (vehicle alone, right flank). No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: None.
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
0.5 g (left flank)
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
Slight skin erythema in 5 animals
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 0.5 g (left flank). No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: Slight skin erythema 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
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 0 (vehicle alone, right flank). No with. + reactions: 0.0. Total no. in groups: 10.0. 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
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 0.5 g (left flank). No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: None.
Reading:
1st reading
Hours after challenge:
1
Group:
test group
Dose level:
0 (vehicle alone, right flank)
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
None
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 1.0. Group: test group. Dose level: 0 (vehicle alone, right flank). No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: None.
Reading:
1st reading
Hours after challenge:
1
Group:
test group
Dose level:
0.5 g (left flank)
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
Slight to moderate skin erythema in 10 animals
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 1.0. Group: test group. Dose level: 0.5 g (left flank). No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: Slight to moderate skin erythema in 10 animals.
Reading:
1st reading
Hours after challenge:
6
Group:
test group
Dose level:
0 (vehicle alone, right flank)
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
None
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 6.0. Group: test group. Dose level: 0 (vehicle alone, right flank). No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: None.
Reading:
1st reading
Hours after challenge:
6
Group:
test group
Dose level:
0.5 g (left flank)
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
Slight to moderate skin erythema in 13 animals
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 6.0. Group: test group. Dose level: 0.5 g (left flank). No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: Slight to moderate skin erythema in 13 animals.
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
0 (vehicle alone, right flank)
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
None
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 0 (vehicle alone, right flank). No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: None.
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
0.5 g (left flank)
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
Slight skin erythema in 8 animals
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 0.5 g (left flank). No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: Slight skin erythema in 8 animals.
Reading:
1st reading
Hours after challenge:
48
Group:
test group
Dose level:
0 (vehicle alone, right flank)
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
None
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: test group. Dose level: 0 (vehicle alone, right flank). No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: None.
Reading:
1st reading
Hours after challenge:
48
Group:
test group
Dose level:
0.5 g (left flank)
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
Slight skin erythema in 3 animals
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: test group. Dose level: 0.5 g (left flank). No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: Slight skin erythema in 3 animals.
Group:
positive control
Remarks on result:
not measured/tested

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. No classification for skin sensitization is warranted based on the absence of positive reactions in the Guinea Pig Maximisation Test, according to the criteria of Annex VI Directive 67/548/EEC or UN/EU GHS.

 

This study is classified as acceptable. It satisfies the OECD 406 guideline requirements for skin sensitization.