Cerium terbium magnesium undecaaluminum nonadecaoxide (hexagonal) ((Ce, Tb)MgAl11O19) and aluminium oxide (Al2O3) from calcination of Al2O3, CeO2, MgO and Tb4O7

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28Sept 2011 to 17Oct 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2012

Report date:

2012

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Deviations:

no

Principles of method if other than guideline:

-

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Cerium terbium magnesium undecaaluminum nonadecaoxide

Molecular formula:

Ce0.5Tb0.5MgAl11O19 -Ce0.7Tb0.3MgAl11O19

IUPAC Name:

Cerium terbium magnesium undecaaluminum nonadecaoxide

Constituent 2

Reference substance name:

Aluminium oxide

EC Number:

215-691-6

EC Name:

Aluminium oxide

Cas Number:

1344-28-1

Molecular formula:

Al2O3

IUPAC Name:

aluminium trioxide

Test material form:

solid: particulate/powder

Details on test material:

- Name of test material (as cited in study report): CAT
- Substance type: white powder

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/J

Sex:

female

Details on test animals and environmental conditions:

- Source: Janvier, Le Genest-Saint-Isle, France
- Age at study initiation: Young adult animals (approx. 9 weeks old)
- Weight at study initiation: Body weight variation was within +/- 20% of the sex mean.
- Housing: Animals were group housed in Makrolon cages
- Diet: Free access to pelleted rodent diet (SM R/M-Z from SSNIFF® Spezialdiäten GmbH, Soest, Germany).
- Water: Free access to tap water.
- Acclimation period: At least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20.1-23.4
- Humidity (%): 41 - 70
- Air changes (per hr): approx 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 28Sept 2011 to 17Oct 2011

Study design: in vivo (LLNA)

Vehicle:

propylene glycol

Concentration:

0, 10, 25, 50% w/w

No. of animals per dose:

5

Details on study design:

RANGE FINDING TESTS:
In a pre-screen test, two young adult animals per concentration (25% and 50% w/w) were treated and ear thickness was measured. Signs of systemic toxicity/ irritation and ear thickning were recorded.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: Local Lymph Node Assay
- Criteria used to consider a positive response: DPM values are presented for each animal and for each dose group. A Stimulation Index (SI) is calculated for each group. The SI is the ratio of the DPM/group compared to DPM/vehicle control group. If the results indicate a SI ≥ 3, the test substance may be regarded as a skin sensitizer, based on the test guideline and recommendations done by ICCVAM.

TREATMENT PREPARATION AND ADMINISTRATION:
Test substance preparation: The test substance formulations (w/w) were prepared within 4 hours prior
to each treatment. No adjustment was made for specific gravity of the vehicle. Homogeneity was obtained to visually acceptable levels.
Rationale for vehicle: The vehicle was selected based on trial formulations performed at NOTOX and on test substance data supplied by the sponsor.

Induction - Days 1, 2 and 3; Excision of nodes - Day 6; Tissue processing for radioacitivity - Day 6; Radioactivity measurements - Day 7; Performed according to test guidelines.

Observations:
Mortality/Viability: Twice daily.
Body weights: On Day 1 (pre-dose) and Day 6 (prior to necropsy).
Clinical signs: Once daily on Days 1-6 (on Days 1-3 between 3 and 4 hours after dosing).
Irritation: Once daily on Days 1-6 (on Days 1 - 3 immediately after dosing) by numerical scoring according to the testguideline. Furthermore, a description of all other (local) effects was recorded.

Positive control substance(s):

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

Statistics:

Not performed.

Results and discussion

Positive control results:

The six-month reliability check with Alpha-hexylcinnamicaldehyde indicates that the Local Lymph Node Assay as performed at NOTOX is an appropriate and reliable model for testing of contact hypersensitivity.

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Value:

1.9

Test group / Remarks:

10%

Results 2

Key result

Parameter:

SI

Value:

1.7

Test group / Remarks:

25%

Results 3

Key result

Parameter:

SI

Value:

1.8

Test group / Remarks:

50%

Cellular proliferation data / Observations:

Mean DPM/animal values for the experimental groups treated with test substance concentrations 10, 25 and 50% were 264, 238 and 250 DPM respectively. The mean DPM/animal value for the vehicle control group was 137 DPM.

Any other information on results incl. tables

Results Pre-screen test:

At both 25% and 50% test substance concentrations no signs of systemic toxicity were noted and no severe irritation was observed. Variations in ear thickness during the observation period were less than 25% from Day 1 pre-dose values. Test substance remnants were present on the dorsal surface of the ears of all animals on Days 1-3, but did not hamper scoring of erythema. Based on these results, the highest test substance concentration selected for the main study was a 50% concentration.

Other results - main study:

No irritation of the ears was observed in any of the animals examined. Test substance remnants were present on the dorsal surface of the ears of animals at 10%, 25% and 50% on Day 1 and/or Days 2-3, but did not hamper scoring of erythema.

 

All auricular lymph nodes of the animals treated with the test substance appeared smaller in size when compared with the nodes of the control group. No macroscopic abnormalities of the surrounding area were noted in any of the animals.

No mortality occurred and no clinical signs of systemic toxicity were observed in the animals of the main study. Body weights and body weight gain of experimental animals remained in the same range as controls over the study period. The body weight loss noted for two control animals, two animals at 25% and one animal at 50% was considered not toxicologically significant since the changes were slight in nature and not concentration-related.

Applicant's summary and conclusion

Interpretation of results:

other: the substance does not need to be classified for skin sensitisation according to GHS and CLP

Conclusions:

In an LLNA skin sensitisation study performed according to OECD/EC test guidelines, CAT was found not to be a skin sensitizer, as the SI measured was not ≥3 when tested up to 50% w/w.

Executive summary:

In the mouse (local lymph node assay) contact hypersensitivity to CAT was assessed by open application of the substance (in concentrations 0, 10, 25 and 50% w/w in propylene glycol) on three sequential days to the outer ear of mice (5/ dose). On day 6, mice were injected with 3H-methyl thymidine. After 5 hours, draining lymph nodes of the ear were collected and tested for radioactivity. The SI was calculated by the ratio of the DPM/group compared to DPM/vehicle control group. No irritation of the ears was observed in any of the animals examined. The SI values calculated for the substance concentrations 10, 25 and 50% were 1.9, 1.7 and 1.8 respectively. Since the test substance did not elicit an SI ≥ 3 when tested up to 50%, CAT was considered not to be a skin sensitizer.