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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:
from 16-OCT-1995 to 6-MAR-1996
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1996
Report date:
1996

Materials and methods

Test guidelineopen allclose all
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
no
Qualifier:
equivalent or similar to guideline
Guideline:
EU Method B.6 (Skin Sensitisation)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of study:
other: Modified Buehler test
Justification for non-LLNA method:
Study was performed before the LLNA method became the preferred method for skin sensitisation testing.

Test material

Constituent 1
Reference substance name:
Reaction mass of cerium dioxide and zirconium dioxide
IUPAC Name:
Reaction mass of cerium dioxide and zirconium dioxide
Test material form:
solid: particulate/powder
Details on test material:
- Name of test material (as cited in study report): Poudre catalytique à base d'oxyde de cérium et d'oxyde de zirconium (OBD 30)
- Substance type: multi-constituent substance
- Physical state: yellow powder
- Further information on test material confidential

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: Centre d'Elevage Lebeau, 78950 Gambais, France
- Age at study initiation: 1 - 3 months
- Weight at study initiation: 320 +/- 25 g for the males; 328 +/- 17 g for the females
- Housing: Housed individually in polycarbonate cages with stainless steel lid (48 cm x 27 cm x 20 cm) equipped with a polypropylene bottle. Sifted and dusted sawdust was provided as litter (SICSA, 92142 Alfortville, France). An analysis of potential residues and major contaminants is performed periodically (Laboratoire Wolff, 92110 Clichy, France).
- Diet: Free access to "guinea-pigs sustenance reference 106 diet" (U.A.R., 91360 Villemoison-sur-Orge, France). Food was periodically analysed (composition and contaminants) by the supplier.
- Water: Drinking water filtered by a FG Millipore membrane (0.22 micron) was provided ad libitum.
- Acclimation period: At least 5 days before the beginning of the study.

ENVIRONMENTAL CONDITIONS
- Temperature: 21 +/- 2 °C
- Humidity: 30 to 70%
- Air changes: The air was non-recycled and filtered
- Photoperiod: light/dark cycle: 12 h/12 h

IN-LIFE DATES: From: 13-NOV-1995 To: 14-DEC-1995

Study design: in vivo (non-LLNA)

Induction
Route:
epicutaneous, occlusive
Vehicle:
other: aqueous solution of methylcellulose at 0.5%
Concentration / amount:
20% (w/w) in 0.5% methylcellulose aqueous solution
Amount applied: 0.5 mL
Day(s)/duration:
Day 1, 3, 5, 8, 10, 12, 15, 17 and 19 (6 h per exposure)
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
Challenge
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
other: aqueous solution of methylcellulose at 0.5%
Concentration / amount:
20% (w/w) in 0.5% methylcellulose aqueous solution
Day(s)/duration:
Day 28, 6 h of exposure
Adequacy of challenge:
not specified
No. of animals per dose:
No. of animals per dose: 10 animals for control group (5M/5F) and 20 animals for treated group (10M/10F).
Details on study design:
RANGE FINDING TESTS:
A preliminary test was performed to define the maximum concentration to be tested. 0.5 mL of the test substance at a concentration of 20% (w/w) in 0.5% methylcellulose aqueous solution was applied to a clipped area of the skin of approximately 4 cm2. The test substance was prepared on a dry gauze pad and then held in place by means of an occlusive dressing for 6 hours. 24 and 48 hours after application of the test substance, scoring of cutaneous reactions was performed. No residual test substance was observed upon removal of the dressings.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 9
- Type of epicutaneous induction: occlusive
- SLS application: No
- Exposure period: On days 1, 3, 5, 8, 10, 12, 15, 17 and 19 (6 h per exposure)
- Test groups: 0.5 mL of the test substance at a concentration of 20% (w/w) in the vehicle. The maximum concentration of the test substance which could be obtained in the vehicle was 20% (w/w).
- Control group: vehicle alone
- Site: anterior left flank
- Frequency of applications: 3 times a week for 3 consecutive weeks
- Duration: 19 days. Following the induction period, the animals received no treatment for 10 days, from day 19 to day 28 inclusive.
- Concentrations: 20% (w/w) in 0.5% methylcellulose aqueous solution

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: Day 29
- Exposure period: 6 h, right flank
- Test groups: Application of 0.5 mL of the test substance at a concentration of 20% (w/w) in the vehicle on an area of 4 cm2 (2 cm x 2 cm) of the posterior right flank (not treated before) under occlusive dressing.
- Control group: Application of 0.5 mL of the test substance at concentration of 20% (w/w) in the vehicle on an area of 4 cm2 (2 cm x 2 cm) of the posterior right flank (not treated before) under occlusive dressing.
- Site: right flank (test substance), left flank (vehicle)
- Concentrations: 20% (w/w) in the vehicle
- Evaluation: 24 and 48 hours after patch removal
Positive control substance(s):
yes
Remarks:
2,4-dinitrochlorobenzene

Results and discussion

Positive control results:
The sensitivity of guinea pigs was checked with a positive sensitiser: 2,4-dinitrochlorobenzene. Induction application: from 0.5 to 0.1% (9 applications). Challenge application: 0.5% (right flank), paraffin oil (left flank).
Under the experimental conditions and according to the modified Buehler method (9 exposures), 2,4-dinitrochlorobenzene at a concentration of 0.5% (w/w) induced positive skin sensitisation reactions in 80% of the guinea pigs.

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
20% (w/w)
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
none
Remarks on result:
no indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
20% (w/w)
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
none
Remarks on result:
no indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
20% (w/w)
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
none
Remarks on result:
no indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
20% (w/w)
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
none
Remarks on result:
no indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
0.5%
No. with + reactions:
8
Total no. in group:
10
Clinical observations:
not reported
Remarks on result:
positive indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
0.5%
No. with + reactions:
8
Total no. in group:
10
Clinical observations:
not reported
Remarks on result:
positive indication of skin sensitisation

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
The test item (reaction mass of cerium dioxide and zirconium dioxide) is not to be classified as a skin sensitiser according to the results of the Modified Buehler test.
Executive summary:

The sensitisation potential of the reaction mass of cerium dioxide and zirconium dioxide was evaluated on Dunkin-Hartley guinea pigs by cutaneous application according to the modified Buehler test and in compliance with Good Laboratory Practice.

 

During the induction period, 10 male and 10 female animals received 0.5 mL of 20% w/w reaction mass of cerium dioxide and zirconium dioxide in 0.5 % methylcellulose aqueous solution, applied to the back on the left side of the spinal column. The substance was held in place for 6 hours with an occlusive dressing. This procedure was repeated 3 times a week for 3 weeks (total: 9 inductions). Control animals (5 males and 5 females) received the vehicle on the left flank using the same experimental conditions. After a 10-day rest period, a cutaneous challenge application of 0.5 mL of the test substance at a concentration of 20% (w/w) in 0.5% methylcellulose aqueous solution (right flank) and the application of the vehicle (left flank) were performed on a non-treated area of the posterior region of all the animals. The cutaneous reactions were evaluated 24 and 48 hours after the challenge application.

 

No clinical signs and no deaths were observed during the study. 24 and 48 hours after removal of the challenge pads, no cutaneous reactions were observed in both control and treated groups. The susceptibility of the guinea pigs lot was confirmed by the positive result obtained with dinitrochlorobenzene in a recent study.

 

The reaction mass of cerium dioxide and zirconium dioxide is not classified as a sensitiser according to the criteria laid down in the CLP Regulation.