Lanthanum oxide

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 24-OCT-2005 to 27-DEC-2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study performed according to an international guideline and according to GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2005

Report date:

2005

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Version / remarks:

Cited as Directive 96/54/EC, B.6

Deviations:

no

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

The guinea pig maximisation test was already available and was used to cover the endpoint in order to not sacrifice further animals. Furhtermore for hardly soluble inorganic compounds the maximisation test is considered often more reliable than the LLNA.

Test material

Test material information

Constituent 1

Reference substance name:

Lanthanum oxide

EC Number:

215-200-5

EC Name:

Lanthanum oxide

Cas Number:

1312-81-8

Molecular formula:

La2O3

IUPAC Name:

lanthanum(3+);oxygen(2-)

In vivo test system

Test animals

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS:
- Source: Charles River Deutschland GmbH
- Age at study initiation: 5 - 6 weeks
- Weight at study initiation: 336 - 392 g
- Housing: individually in Makrolon type-4 cages with standard softwood bedding
- Diet: pelleted standard Provimi Kliba 3418, ad libitum
- Water: community tap water from Füllinsdorf, ad libitum
- Acclimation period: 13 days

ENVIRONMENTAL CONDITIONS
- Temperature: 22 +/- 3 °C
- Humidity: 30 - 70 %
- Air changes: 10 - 15 per hr
- Photoperiod: 12 hrs dark / 12 hrs light

IN-LIFE DATES: from 08-NOV-2005 to 02-DEC-2005

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal and epicutaneous

Vehicle:

other: PEG 300

Induction 2

Concentration / amount:

15 and 25% w/w (intradermal induction), 50 % w/w (epidermal induction and challenge)
1st application: Induction 25 % intracutaneous
2nd application: Induction 50 % occlusive epicutaneous
3rd application: Challenge 50 % occlusive epicutaneous

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

other: PEG 300

Challenge 2

Concentration / amount:

15 and 25% w/w (intradermal induction), 50 % w/w (epidermal induction and challenge)
1st application: Induction 25 % intracutaneous
2nd application: Induction 50 % occlusive epicutaneous
3rd application: Challenge 50 % occlusive epicutaneous

No. of animals per dose:

15 (main study: 5 in control group, 10 in test group), 3 (pretest)

Details on study design:

* RANGE FINDING TEST:
>>> INTRADERMAL INJECTIONS:
One guinea pig was intradermally injected into the clipped flank at concentrations of B = 25 % and C = 15 % (w/w) of the test item in PEG 300. Due to the high viscosity of the application dilution and the obstacle caused by the tissues, it was not technically possible to inject the liquid dilution at concentration of A = 50 % (w/w) into the intra-cellular space.
Dermal reactions were assessed approximately 24 hours later.
Based on the results, the test item concentration of 25 % was selected for intradermal induction in the main study. However, due to the high viscosity of the test item preparation, the two first animals of the test group could not be applied successfully (only partial application) intracutaneously with the test item concentration of 25 % (w/w) in PEG 300. Therefore, the next lower concentration of 15 % (w/w) tested in the pretest was selected.

>>> EPIDERMAL APPLICATION:
4 patches of filter paper were saturated with the test item at D = 50 % (technically the highest possible concentration to be applied sufficiently), E = 25 %, F = 15 % and G = 10 % (w/w) in PEG 300 and applied to the clipped and shaved flanks of 2 guinea pigs. The patches were covered by a strip of aluminum foil and firmly secured by elastic plaster wrapped around the trunk and covered with impervious adhesive tape.
21 hours after removal of the dressing the application site was depilated in order to visualize any resulting erythema.
3 hours later (48 hours from the epidermal application) the skin reaction was observed and recorded. After this observation a second observation (approximately 72 hours from the epidermal application) was made and once again recorded.
Based on the results obtained the concentration selected for induction and challenge in the main study was 50 % (w/w).


* MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2
- Type of epicutaneous induction: occlusive
- SLS application: yes (0.5 mL at 10% w/w)
- Exposure period: on D1 (intradermal) and D8 (epidermal, 48-hr exposure)
- Test groups:
>>> Intradermal induction:
1) 1:1 (v/v) mixture of Freund's Complete Adjuvant and physiological saline
2) The test item at 25 % or 15 % (w/w) in PEG 300
3) The test item at 25 % or 15 % (w/w) in a 1:1 (v/v) mixture of Freund's Complete Adjuvant and physiological saline
>>> Epidermal application: test item at 50 % (w/w) in PEG 300
- Control group:
>>> Intradermal induction:
1) 1:1 (v/v) mixture of Freund's Complete Adjuvant and physiological saline
2) PEG 300
3) 1:1 (w/w) mixture of PEG 300 in a 1:1 (v/v) mixture of Freund's Complete Adjuvant and physiological saline
>>> Epidermal application: PEG 300 only
- Site: dorsal skin of the scapular region
- Frequency of applications: not applicable
- Duration: 8 days (duration of the induction phase)
- Concentrations: 15 or 25 % w/w by intradermal injection, 50 % by epidermal application

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day of challenge: day 22
- Exposure period: 24 hours
- Test groups: test item in the vehicle only (+ vehicle only in the other flank)
- Control group: test item in the vehicle only (+ vehicle only in the other flank)
- Site: left (test item) and right (vehicle) flanks
- Concentrations: 50% (w/w)
- Evaluation: 48 hr after the beginning of the challenge

- Statistics: descriptive statistics were calculated for body weights. No inferential statistics were used.

Positive control substance(s):

yes

Remarks:

hexyl cinnamic aldehyde (CAS No 101-86-0) (regularly control)

Results and discussion

Positive control results:

hexyl cinnamic aldehyde was tested in the same conditions as described above. Based on the findings, hexyl cinnamic aldehyde at 1% in PEG 300 was considered as a skin sensitizer.
The positive control was not included in the study, but put in an other report , as regularly control.

In vivo (non-LLNA)

Results

Results 1

Key result

Reading:

1st reading

Hours after challenge:

48

Group:

negative control

Dose level:

0 %

No. with + reactions:

0

Total no. in group:

5

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 0 %. No with. + reactions: 0.0. Total no. in groups: 5.0.

Results 2

Key result

Reading:

1st reading

Hours after challenge:

48

Group:

test chemical

Dose level:

50%

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 48.0. Group: test group. Dose level: 50%. No with. + reactions: 0.0. Total no. in groups: 10.0.

Results 3

Key result

Reading:

1st reading

Hours after challenge:

48

Group:

positive control

Dose level:

1%

No. with + reactions:

4

Total no. in group:

10

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 48.0. Group: positive control. Dose level: 1%. No with. + reactions: 4.0. Total no. in groups: 10.0.

Results 4

Key result

Reading:

2nd reading

Hours after challenge:

72

Group:

negative control

Dose level:

0%

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

In the test and control groups, no skin reactions were observed in the animals when treated with either PEG 300 only or when treated with the test item at 50 % (w/w) in PEG 300.

Remarks on result:

other: see Remark

Remarks:

Reading: 2nd reading. . Hours after challenge: 72.0. Group: negative control. Dose level: 0%. No with. + reactions: 0.0. Total no. in groups: 5.0. Clinical observations: In the test and control groups, no skin reactions were observed in the animals when treated with either PEG 300 only or when treated with the test item at 50 % (w/w) in PEG 300..

Results 5

Key result

Reading:

2nd reading

Hours after challenge:

72

Group:

test chemical

Dose level:

50%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

no mortality, no sign of systemic toxicity and no effect on body weight were observed during the study.

Remarks on result:

other: see Remark

Remarks:

Reading: 2nd reading. . Hours after challenge: 72.0. Group: test group. Dose level: 50%. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: no mortality, no sign of systemic toxicity and no effect on body weight were observed during the study..

Results 6

Key result

Reading:

2nd reading

Hours after challenge:

72

Group:

positive control

Dose level:

1%

No. with + reactions:

1

Total no. in group:

10

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: positive control. Dose level: 1%. No with. + reactions: 1.0. Total no. in groups: 10.0.

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information

Conclusions:

Lanthane oxide is not classified as skin sensitising according to Annex VI of the Directive 67/548/EEC.

Executive summary:

The sensitisation potential of Lanthane oxide was evaluated on Dunkin-Hartley guinea pigs according to the maximisation method of Magnusson and Kligman, described in Directive 67/548/EEC, method B.6, and in compliance with Good Laboratory Practice.

Ten test and five control guinea pigs were included in this study. Induction was carried out as the following:

- on day one, animals were injected by the intracutaneous route with Lanthane oxide (15 and 25% % w/w in PEG 300) +/- Freund Complete Adjuvant (treated group) or with PEG 300 +/- Freund Complete Adjuvant (control group) or with Freund Complete Adjuvant alone (both groups);

- on day 7, the same region received a topical application of sodium lauryl sulfate (10 % w/w in paraffinum perliquidum) in order to induce local irritation;

- on day 8, a 48-hour topical occlusive application was performed with Lanthane oxide at 50 % w/w in PEG 300 (test animals) or the vehicle (controls).

- on day 22, the control and test animals were challenged by a cutaneous application of the test substance at 50 % w/w in PEG 300 to the left flank. The right flank served as control and received the vehicle only. The test substance and the vehicle were maintained under an occlusive dressing for 24 hours.

Skin reactions (erythema and oedema) were evaluated approximately 24 and 48 hours after removal of the dressing.

No clinical signs and no deaths related to treatment were noted during the study.

After the challenge application, at the 24-hour and 48-hour readings, no cutaneous reactions were noted.

In this study, Lanthane oxide is not a dermal sensitizer.