Rhodium trinitrate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

21 January 2003 – 21 March 2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Study conducted according to GLP and based on the guidelines described in OECD Guideline No. 406, EC Commission Directive 96/54/EC, EPA OPPTS 870.2600 and JMAFF: Japanese Test Guidelines, and based on the method of Magnusson and Kligman.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2003

Report date:

2003

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Deviations:

no

Test guideline 4

Qualifier:

according to guideline

Guideline:

other: Japanese Ministry of Agriculture, Forestry and Fisheries (MAFF): Japanese Test Guidelines (draft). Test Reports accompanying an application for registration. Unauthorized English translation, July 2000.

Deviations:

no

Test guideline 5

Qualifier:

according to guideline

Guideline:

other: Magnusson B and Kligman AM (1970). Allergic contact dermatitis in th guinea-pig: identification of contact allergens. Published by CC Thomas, Springfield, Illinois, USA.

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

Study conducted in 2003

Test material

Test material information

Constituent 1

Reference substance name:

Rhodium(III) nitrate hydrate

EC Number:

603-842-2

Cas Number:

13465-43-5

Molecular formula:

H4N3O11Rh

IUPAC Name:

Rhodium(III) nitrate hydrate

Details on test material:

- Name of test material (as cited in study report): rhodiumtrinitrate hydrate
- Molecular formula (if other than submission substance): Rh(NO3)3
- Molecular weight (if other than submission substance): 288.9
- Structural formula attached as image file (if other than submission substance): see Fig.


- Substance type: green-brown powder
- Physical state: solid
- Analytical purity: no data
- Composition of test material, percentage of components: rhodium 35.7% +/- 0.1%
- Lot/batch No.: 2586/00-02
- Expiration date of the lot/batch: 21 October 2003
- Stability under test conditions: stable
- Storage condition of test material: at room temperature in the dark

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, Kisslegg, Germany
- Age at study initiation: approx. 4 weeks old
- Weight at study initiation: no data
- Housing: maximally 5 animals/cage with purified sawdust as bedding material
- Diet: ad libitum standard guinea pig diet, including 1 g ascorbic acid/kg (Charles River Breeding and Maintenance Diet for Guinea Pigs), Altromin, Lage., Germany.
- Water: ad libitum with added vitamin C (200 mg/L, Dopharma, Raamsdonkveer, Netherlands)
- Acclimation period: at least 5 days before the start of treatment under laboratory conditions

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 ± 3
- Humidity (%): 30-70 (“Deviations from the maximum level for relative humidity (with a maximum of 20%) did occur which might have been caused by cleaning procedures in the room”, but these deviations were not considered to have affected the study integrity.)
- Air changes (per hr): approx. 15
- Photoperiod (hrs dark / hrs light): 12 hrs artificial fluorescent light and 12 hrs dark per day

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal and epicutaneous

Vehicle:

water

Induction 2

Concentration / amount:

0.01 or 0.02% concentrations used in the intradermal induction procedure, 0.5 ml of a 20% concentration used in the epidermal induction procedure and 0.1 ml of a 20% concentration used in the challenge procedure.

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

water

Challenge 2

Concentration / amount:

0.01 or 0.02% concentrations used in the intradermal induction procedure, 0.5 ml of a 20% concentration used in the epidermal induction procedure and 0.1 ml of a 20% concentration used in the challenge procedure.

No. of animals per dose:

10 females/experimental group; 5 females/control group

Details on study design:

RANGE FINDING TESTS:
A series of four test substance concentrations was used for both intradermal injection and epidermal application, the highest being 5% since corrosion was expected at higher concentrations.

For the intradermal injection range finder, each of 2 animals aged between 4 and 9 weeks old received two different concentrations (5 and 2%, and 1 and 0.5%) in duplicate (0.1 ml/site) in the clipped scapular region and the resulting dermal reactions were assessed 24 and 48 hrs after treatment. Based on the results, 3 additional animals were tested in a similar way with 6 lower concentrations (0.2 and 0.1%, 0.05 and 0.02%, and 0.01 and 0.005%) at a later stage.

For the epidermal application, 6 animals received 2 different concentrations (5 and 2%, 1 and 0.5%, or 20 and 10%) applied (0.5 ml each) to the clipped flank using Metalline patches (2x3 cm) mounted on Medical tape, whereas 2 animals recieved the highest test concentration (50%) only. These were held in place with Micropore tape and a Coban elastic bandage. The dressing was removed after 24 hrs, the skin cleaned of residual test substance using water and the resulting dermal reactions assessed for irritation 24 and 48 hrs later.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: three pairs of intradermal injections and one topical application
- Exposure period: patch test applied for 48 hrs, 7 days after the intradermal injections
- Test groups: one
- Control group: yes
- Site: the clipped scapular region
- Frequency of applications: intradermal injections on day 1 followed by a 48-hr dermal application on day 8.
- Duration: 9 days
- Concentrations: 0.1 ml of a 0.01% concentration of the test substance/site or 0.1 ml of a 1:1 w/w mixture of 0.02% of the test substance and Freund’s Complete Adjuvant/site in the intradermal injections, 0.5 ml of a 20% test substance concentration in the epidermal application.

B. CHALLENGE EXPOSURE
- No. of exposures: one
- Day(s) of challenge: day 22
- Exposure period: 24 hrs
- Test groups: one
- Control group: yes
- Site: clipped skin on the flank
- Concentrations: 0.1 ml of a 20% test substance concentration
- Evaluation (hr after challenge): 24 and 48 hrs after removal of the patch

OTHER:
The epidermal induction application used a Metalline patch (2x3 cm) mounted on Medical tape, which was held in place with Micropore tape and a Coban elastic bandage. With the challenge application, Curatest, Patch Test Plasters were used and were held in place with Micropore tape and Coban elastic bandage.

Challenge controls:

The control group of guinea pigs was treated in the same way as for the experimental animals except that water was used instead of the test material at induction.

Positive control substance(s):

yes

Remarks:

historical control (alpha-hexylcinnamicaldehyde) confirms the reliability of the test system

Results and discussion

Positive control results:

Historical control data with 20% alpha-hexylcinnamicaldehyde gave positive results in this test system (50% sensitisation rate), confirming the reliability of the test system

In vivo (non-LLNA)

Results

Results 1

Reading:

other: 1st reading; 2nd reading

Hours after challenge:

24

Group:

test chemical

Dose level:

20% aqueous solution

No. with + reactions:

10

Total no. in group:

10

Clinical observations:

see below

Remarks on result:

other: Reading: other: 1st reading; 2nd reading. . Hours after challenge: 24.0. Group: test group. Dose level: 20% aqueous solution. No with. + reactions: 10.0. Total no. in groups: 10.0. Clinical observations: see below.

Results 2

Reading:

other: 1st reading; 2nd reading

Hours after challenge:

24

Group:

negative control

Dose level:

0 and 20% aqueous solution

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

None reported

Remarks on result:

other: Reading: other: 1st reading; 2nd reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 0 and 20% aqueous solution. No with. + reactions: 0.0. Total no. in groups: 5.0. Clinical observations: None reported.

Any other information on results incl. tables

The results of the preliminary study indicated that a 0.01% concentration of the test substance should be used for the intradermal induction phase (as erythema grade 1 seen, but no necrosis at this concentration) and 20% concentrations should be used for both the epidermal induction and challenge phases (as the highest concentration without signs of necrosis). Yellow staining observed at 0.5% (but not 0.2%) following intradermal injection and at all test concentrations (0.5% and above) following epidermal application.

Grade 1 skin reactions were seen in 2 of the test group animals and scabs and/or scaliness was seen in all of the animals following the challenge application. At the treated skin sites, yellow staining was observed at both the 24 and 48-hr observation times. There was no mortality, no symptoms of systemic toxicity and no effects on body weights or body weight gain.

Applicant's summary and conclusion

Interpretation of results:

Category 1A (indication of significant skin sensitising potential) based on GHS criteria

Conclusions:

Rhodium trinitrate hydrate induced skin sensitisation in all of the treated animals in a guideline guinea pig maximisation test.

Executive summary:

The ability of rhodium trinitrate hydrate to induce contact sensitisation was assessed in an OECD Test Guideline 406 guinea pig maximisation test (GPMT), conducted to GLP, using groups of 10 test and 5 control females.

Animals were induced via intradermal injection (0.1 ml/site) at a test concentration of 0.01% (with and without FCA), followed one week later by a second induction by topical application of 20% of the test substance under a 48-hr occlusive patch. Control animals were similarly treated but without the test substance. A challenge dose of 20% was applied under an occlusive patch for 24 hr, three weeks after the start of induction, to both test and control animals. Scoring of the treated areas was carried out 24 and 48 hr after removal of the patches.

When challenged, all ten of the test animals exhibited skin reactions (including scabs and/or scaliness) indicative of sensitisation. No such reactions were seen in any of the control animals. Therefore, rhodium trinitrate hydrate displayed evidence of skin sensitisation in a reliable GPMT.

Based on the results of this study, rhodium trinitrate should be classified as an extreme skin sensitiser (category 1A) according to EU CLP criteria (EC 1272/2008).